2011

David Turner I Bishoy Takla

Homeowners Handbook for Energy

Conservation

Master of Science ndash Sustainability in

the Urban Environment

Economics of the Environment and

Natural Resources

Professor Kevin Foster

Page 1 of 47

Contents Introduction 2

Windows 4

Non-solar heat flow 5

Recommendation for selecting window U-value 10

Solar Gain 10

Recommendation for selecting SHGC 13

Ventilation and Airtightness 13

Preventing condensation 15

Daylighting 16

The NFRC Label 16

Cost analysis 17

Passive Systems 23

Landscaping for Energy Efficiency 23

Winter 24

Summer 31

All Seasons 35

Cost Analysis 36

Market Incentives 41

References 43

Page 2 of 47

Introduction

Would you drink out of a leaky glass or water your plants with a leaky pale No you

wouldn‟t because it is counterproductive to your task of effectively drinking and watering So

why are we living in homes that allow heat to escape in the winter and cool air to escape in the

summer if our task is to efficiently regulate the temperature inside our homes Because we can‟t

physically see the heat from our boilers or the cool air from our air conditioners actually flow out

of the various crevices that need to be plugged the way that you can see water flowing out of a

bucket with holes in it (Figure 1)

In this handbook we are going to focus on improving

the thermal envelope and supplement with passive systems as a

retrofit to existing homes By improving the thermal envelope

we will reduce the dependence on electricity and mechanical

heating systems Passive systems will aid the thermal envelope

solutions by reducing that dependence as well (Figure 2)

Figure 1 Analogy comparing water loss from a bucket to heat loss in a building

Figure 2 Three tier system to reduce home

energy consumption

Page 3 of 47

The purpose of this handbook is to introduce a few methods to reduce one‟s dependence

on conventional heating cooling and lighting by effectively enclosing the thermal envelope and

passively making the most out of the microclimate for the average homeowner within the New

York City metropolitan area (Figure 3) We will explain how these methods will reduce one‟s

consumption and lower their utility bills Specifically we will look at reduction of natural gas

consumption and costs for heating in the winter reduction of electricity consumption and costs

for cooling in the summer and reduction of electricity consumption and costs for lighting year

round Some questions we hope to answer include How can these methods reduce consumption

for the average New Yorker How much money and energy can be saved in the long run What

is the return-on-investment Is it worthwhile for me to implement these energy saving solutions

Figure 3 Diagram showing heat loss and gain throughout a building

Page 4 of 47

Windows

As mentioned in the introduction the main goal of this paper is to improve the efficiency

of your home and respectively decrease your monthly bills You might wonder why we started

out by talking about improving your windows Basically your windows are the weakest thermal

link within your home (Figure 4) Single pane windows have no thermal resistance at all and all

its resistance is due to the surface air film (Lechner 2009) therefore selecting the right type of

window for your home is a harder job than it may seem Many factors impact the right choice

energy related and non-energy related We are going to discuss in this section how to choose the

right type of windows for your home what is the future technology for windows and how long

is the payback period for your choice

5 through ceilings

16throughwindows

1 throughbasement floor

17 throughframe walls

3 through door

38 through cracksin walls windowsand doors

20throughbasementwalls

Figure 4 losses of heating energy through house element

Page 5 of 47

Energy flow occurs through windows in three different forms (Figure 5)

1- Non-solar heat loss or gain in form of conduction convection and radiation which is a factor

of the temperature differences between inside and outside

2- Solar heat gain in the form of radiation which is desirable during the heating session and

undesirable during the cooling session

3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes

through cracks and joints) which we will need to minimize as much as possible

Non-solar heat flow

The main reason for heat flow (loss or gain) is the temperature difference between indoor

and outdoor The thermal energy always seeks an equilibrium situation In winter time your

windows lose heat to the outside freezing air in order to achieve this equilibrium state The

opposite happens in the summer months when the air-conditioned indoor air gains heat from the

outside hot air In order for us to minimize this natural flow of air we need to minimize the

windows thermal conductance which is called the U-value

U-value is a measure of the amount of non-solar heat flow

through a window (or other material) expressed in Btuhr-sfdegF U-values

tell us how well a window will allow heat to pass through it A lower U-

value means less heat flow The lower the U-value the greater a products

resistance to heat flow and the better its insulating value U-factors allow

customers to compare the insulating properties of different windows The

area of the window also affects how much heat flow can pass through Figure 5 The energy flow occurs through windows in three different forms

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 1 of 47

Contents Introduction 2

Windows 4

Non-solar heat flow 5

Recommendation for selecting window U-value 10

Solar Gain 10

Recommendation for selecting SHGC 13

Ventilation and Airtightness 13

Preventing condensation 15

Daylighting 16

The NFRC Label 16

Cost analysis 17

Passive Systems 23

Landscaping for Energy Efficiency 23

Winter 24

Summer 31

All Seasons 35

Cost Analysis 36

Market Incentives 41

References 43

Page 2 of 47

Introduction

Would you drink out of a leaky glass or water your plants with a leaky pale No you

wouldn‟t because it is counterproductive to your task of effectively drinking and watering So

why are we living in homes that allow heat to escape in the winter and cool air to escape in the

summer if our task is to efficiently regulate the temperature inside our homes Because we can‟t

physically see the heat from our boilers or the cool air from our air conditioners actually flow out

of the various crevices that need to be plugged the way that you can see water flowing out of a

bucket with holes in it (Figure 1)

In this handbook we are going to focus on improving

the thermal envelope and supplement with passive systems as a

retrofit to existing homes By improving the thermal envelope

we will reduce the dependence on electricity and mechanical

heating systems Passive systems will aid the thermal envelope

solutions by reducing that dependence as well (Figure 2)

Figure 1 Analogy comparing water loss from a bucket to heat loss in a building

Figure 2 Three tier system to reduce home

energy consumption

Page 3 of 47

The purpose of this handbook is to introduce a few methods to reduce one‟s dependence

on conventional heating cooling and lighting by effectively enclosing the thermal envelope and

passively making the most out of the microclimate for the average homeowner within the New

York City metropolitan area (Figure 3) We will explain how these methods will reduce one‟s

consumption and lower their utility bills Specifically we will look at reduction of natural gas

consumption and costs for heating in the winter reduction of electricity consumption and costs

for cooling in the summer and reduction of electricity consumption and costs for lighting year

round Some questions we hope to answer include How can these methods reduce consumption

for the average New Yorker How much money and energy can be saved in the long run What

is the return-on-investment Is it worthwhile for me to implement these energy saving solutions

Figure 3 Diagram showing heat loss and gain throughout a building

Page 4 of 47

Windows

As mentioned in the introduction the main goal of this paper is to improve the efficiency

of your home and respectively decrease your monthly bills You might wonder why we started

out by talking about improving your windows Basically your windows are the weakest thermal

link within your home (Figure 4) Single pane windows have no thermal resistance at all and all

its resistance is due to the surface air film (Lechner 2009) therefore selecting the right type of

window for your home is a harder job than it may seem Many factors impact the right choice

energy related and non-energy related We are going to discuss in this section how to choose the

right type of windows for your home what is the future technology for windows and how long

is the payback period for your choice

5 through ceilings

16throughwindows

1 throughbasement floor

17 throughframe walls

3 through door

38 through cracksin walls windowsand doors

20throughbasementwalls

Figure 4 losses of heating energy through house element

Page 5 of 47

Energy flow occurs through windows in three different forms (Figure 5)

1- Non-solar heat loss or gain in form of conduction convection and radiation which is a factor

of the temperature differences between inside and outside

2- Solar heat gain in the form of radiation which is desirable during the heating session and

undesirable during the cooling session

3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes

through cracks and joints) which we will need to minimize as much as possible

Non-solar heat flow

The main reason for heat flow (loss or gain) is the temperature difference between indoor

and outdoor The thermal energy always seeks an equilibrium situation In winter time your

windows lose heat to the outside freezing air in order to achieve this equilibrium state The

opposite happens in the summer months when the air-conditioned indoor air gains heat from the

outside hot air In order for us to minimize this natural flow of air we need to minimize the

windows thermal conductance which is called the U-value

U-value is a measure of the amount of non-solar heat flow

through a window (or other material) expressed in Btuhr-sfdegF U-values

tell us how well a window will allow heat to pass through it A lower U-

value means less heat flow The lower the U-value the greater a products

resistance to heat flow and the better its insulating value U-factors allow

customers to compare the insulating properties of different windows The

area of the window also affects how much heat flow can pass through Figure 5 The energy flow occurs through windows in three different forms

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 2 of 47

Introduction

Would you drink out of a leaky glass or water your plants with a leaky pale No you

wouldn‟t because it is counterproductive to your task of effectively drinking and watering So

why are we living in homes that allow heat to escape in the winter and cool air to escape in the

summer if our task is to efficiently regulate the temperature inside our homes Because we can‟t

physically see the heat from our boilers or the cool air from our air conditioners actually flow out

of the various crevices that need to be plugged the way that you can see water flowing out of a

bucket with holes in it (Figure 1)

In this handbook we are going to focus on improving

the thermal envelope and supplement with passive systems as a

retrofit to existing homes By improving the thermal envelope

we will reduce the dependence on electricity and mechanical

heating systems Passive systems will aid the thermal envelope

solutions by reducing that dependence as well (Figure 2)

Figure 1 Analogy comparing water loss from a bucket to heat loss in a building

Figure 2 Three tier system to reduce home

energy consumption

Page 3 of 47

The purpose of this handbook is to introduce a few methods to reduce one‟s dependence

on conventional heating cooling and lighting by effectively enclosing the thermal envelope and

passively making the most out of the microclimate for the average homeowner within the New

York City metropolitan area (Figure 3) We will explain how these methods will reduce one‟s

consumption and lower their utility bills Specifically we will look at reduction of natural gas

consumption and costs for heating in the winter reduction of electricity consumption and costs

for cooling in the summer and reduction of electricity consumption and costs for lighting year

round Some questions we hope to answer include How can these methods reduce consumption

for the average New Yorker How much money and energy can be saved in the long run What

is the return-on-investment Is it worthwhile for me to implement these energy saving solutions

Figure 3 Diagram showing heat loss and gain throughout a building

Page 4 of 47

Windows

As mentioned in the introduction the main goal of this paper is to improve the efficiency

of your home and respectively decrease your monthly bills You might wonder why we started

out by talking about improving your windows Basically your windows are the weakest thermal

link within your home (Figure 4) Single pane windows have no thermal resistance at all and all

its resistance is due to the surface air film (Lechner 2009) therefore selecting the right type of

window for your home is a harder job than it may seem Many factors impact the right choice

energy related and non-energy related We are going to discuss in this section how to choose the

right type of windows for your home what is the future technology for windows and how long

is the payback period for your choice

5 through ceilings

16throughwindows

1 throughbasement floor

17 throughframe walls

3 through door

38 through cracksin walls windowsand doors

20throughbasementwalls

Figure 4 losses of heating energy through house element

Page 5 of 47

Energy flow occurs through windows in three different forms (Figure 5)

1- Non-solar heat loss or gain in form of conduction convection and radiation which is a factor

of the temperature differences between inside and outside

2- Solar heat gain in the form of radiation which is desirable during the heating session and

undesirable during the cooling session

3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes

through cracks and joints) which we will need to minimize as much as possible

Non-solar heat flow

The main reason for heat flow (loss or gain) is the temperature difference between indoor

and outdoor The thermal energy always seeks an equilibrium situation In winter time your

windows lose heat to the outside freezing air in order to achieve this equilibrium state The

opposite happens in the summer months when the air-conditioned indoor air gains heat from the

outside hot air In order for us to minimize this natural flow of air we need to minimize the

windows thermal conductance which is called the U-value

U-value is a measure of the amount of non-solar heat flow

through a window (or other material) expressed in Btuhr-sfdegF U-values

tell us how well a window will allow heat to pass through it A lower U-

value means less heat flow The lower the U-value the greater a products

resistance to heat flow and the better its insulating value U-factors allow

customers to compare the insulating properties of different windows The

area of the window also affects how much heat flow can pass through Figure 5 The energy flow occurs through windows in three different forms

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 3 of 47

The purpose of this handbook is to introduce a few methods to reduce one‟s dependence

on conventional heating cooling and lighting by effectively enclosing the thermal envelope and

passively making the most out of the microclimate for the average homeowner within the New

York City metropolitan area (Figure 3) We will explain how these methods will reduce one‟s

consumption and lower their utility bills Specifically we will look at reduction of natural gas

consumption and costs for heating in the winter reduction of electricity consumption and costs

for cooling in the summer and reduction of electricity consumption and costs for lighting year

round Some questions we hope to answer include How can these methods reduce consumption

for the average New Yorker How much money and energy can be saved in the long run What

is the return-on-investment Is it worthwhile for me to implement these energy saving solutions

Figure 3 Diagram showing heat loss and gain throughout a building

Page 4 of 47

Windows

As mentioned in the introduction the main goal of this paper is to improve the efficiency

of your home and respectively decrease your monthly bills You might wonder why we started

out by talking about improving your windows Basically your windows are the weakest thermal

link within your home (Figure 4) Single pane windows have no thermal resistance at all and all

its resistance is due to the surface air film (Lechner 2009) therefore selecting the right type of

window for your home is a harder job than it may seem Many factors impact the right choice

energy related and non-energy related We are going to discuss in this section how to choose the

right type of windows for your home what is the future technology for windows and how long

is the payback period for your choice

5 through ceilings

16throughwindows

1 throughbasement floor

17 throughframe walls

3 through door

38 through cracksin walls windowsand doors

20throughbasementwalls

Figure 4 losses of heating energy through house element

Page 5 of 47

Energy flow occurs through windows in three different forms (Figure 5)

1- Non-solar heat loss or gain in form of conduction convection and radiation which is a factor

of the temperature differences between inside and outside

2- Solar heat gain in the form of radiation which is desirable during the heating session and

undesirable during the cooling session

3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes

through cracks and joints) which we will need to minimize as much as possible

Non-solar heat flow

The main reason for heat flow (loss or gain) is the temperature difference between indoor

and outdoor The thermal energy always seeks an equilibrium situation In winter time your

windows lose heat to the outside freezing air in order to achieve this equilibrium state The

opposite happens in the summer months when the air-conditioned indoor air gains heat from the

outside hot air In order for us to minimize this natural flow of air we need to minimize the

windows thermal conductance which is called the U-value

U-value is a measure of the amount of non-solar heat flow

through a window (or other material) expressed in Btuhr-sfdegF U-values

tell us how well a window will allow heat to pass through it A lower U-

value means less heat flow The lower the U-value the greater a products

resistance to heat flow and the better its insulating value U-factors allow

customers to compare the insulating properties of different windows The

area of the window also affects how much heat flow can pass through Figure 5 The energy flow occurs through windows in three different forms

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 4 of 47

Windows

As mentioned in the introduction the main goal of this paper is to improve the efficiency

of your home and respectively decrease your monthly bills You might wonder why we started

out by talking about improving your windows Basically your windows are the weakest thermal

link within your home (Figure 4) Single pane windows have no thermal resistance at all and all

its resistance is due to the surface air film (Lechner 2009) therefore selecting the right type of

window for your home is a harder job than it may seem Many factors impact the right choice

energy related and non-energy related We are going to discuss in this section how to choose the

right type of windows for your home what is the future technology for windows and how long

is the payback period for your choice

5 through ceilings

16throughwindows

1 throughbasement floor

17 throughframe walls

3 through door

38 through cracksin walls windowsand doors

20throughbasementwalls

Figure 4 losses of heating energy through house element

Page 5 of 47

Energy flow occurs through windows in three different forms (Figure 5)

1- Non-solar heat loss or gain in form of conduction convection and radiation which is a factor

of the temperature differences between inside and outside

2- Solar heat gain in the form of radiation which is desirable during the heating session and

undesirable during the cooling session

3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes

through cracks and joints) which we will need to minimize as much as possible

Non-solar heat flow

The main reason for heat flow (loss or gain) is the temperature difference between indoor

and outdoor The thermal energy always seeks an equilibrium situation In winter time your

windows lose heat to the outside freezing air in order to achieve this equilibrium state The

opposite happens in the summer months when the air-conditioned indoor air gains heat from the

outside hot air In order for us to minimize this natural flow of air we need to minimize the

windows thermal conductance which is called the U-value

U-value is a measure of the amount of non-solar heat flow

through a window (or other material) expressed in Btuhr-sfdegF U-values

tell us how well a window will allow heat to pass through it A lower U-

value means less heat flow The lower the U-value the greater a products

resistance to heat flow and the better its insulating value U-factors allow

customers to compare the insulating properties of different windows The

area of the window also affects how much heat flow can pass through Figure 5 The energy flow occurs through windows in three different forms

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 5 of 47

Energy flow occurs through windows in three different forms (Figure 5)

1- Non-solar heat loss or gain in form of conduction convection and radiation which is a factor

of the temperature differences between inside and outside

2- Solar heat gain in the form of radiation which is desirable during the heating session and

undesirable during the cooling session

3- Heat loss through ventilation (intended air changes) or infiltration (unintended air changes

through cracks and joints) which we will need to minimize as much as possible

Non-solar heat flow

The main reason for heat flow (loss or gain) is the temperature difference between indoor

and outdoor The thermal energy always seeks an equilibrium situation In winter time your

windows lose heat to the outside freezing air in order to achieve this equilibrium state The

opposite happens in the summer months when the air-conditioned indoor air gains heat from the

outside hot air In order for us to minimize this natural flow of air we need to minimize the

windows thermal conductance which is called the U-value

U-value is a measure of the amount of non-solar heat flow

through a window (or other material) expressed in Btuhr-sfdegF U-values

tell us how well a window will allow heat to pass through it A lower U-

value means less heat flow The lower the U-value the greater a products

resistance to heat flow and the better its insulating value U-factors allow

customers to compare the insulating properties of different windows The

area of the window also affects how much heat flow can pass through Figure 5 The energy flow occurs through windows in three different forms

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 6 of 47

it The bigger the window is the more heat flow will pass through it The mathematical formula

that expresses these factors is

Q = U-value x Area x Delta T

Where U is the U-Value of the window (including the frame) in Btuhr-sfdegF A is the window

area in SF and Delta T is the temperature difference between the inside and outside temperature

in degree Fahrenheit

This formula is very useful to calculate the heat flow through a window at a specific

moment in time However we are more interested in calculating the total heat flow during the

whole session or even the whole year Thus we need to use the Heating Degree Day (HDD)

which is the number of degrees that a days average temperature is below 65 degF For example

NYC temperature on January 21st had a high temperature of 32 degF and a low temperature of

18 degF with a mean temperature of 25 degF The HDD calculation for this day is 65-25= 40 HDD is

a measurement designed to reflect the need for energy to heat your home In the same way

summer Cooling Degree Days (CCD) are the number of degrees that a day‟s average temperature

is above 65 degF which are the degrees that need to be removed from the home in order to achieve

thermal comfort (65degF)

HDD and CDD are widely available for each specific location You can use

wwwnyserdaorg to see the HDD for your city Table 1 shows the HDD and CDD for NYC As

you can see the HDD is greater than the CDD because NYC is a heating climate

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 7 of 47

Table 1 HHD and CDD for NYC

Now how can we improve the windows‟ U-value Windows are the weakest thermal

point in your home (Figure 6) For example to reach the same thermal resistance as a

conventional insulated stud wall (R-14) it would take about 13 sheets of glass and 12 air spaces

in between them (Figure 7) The U-value for a single pane window is mainly due to the thin film

of air on the interior and a layer of air on the exterior which is about 061 and 017 (hsfdegFBtu)

respectively By adding an extra layer of glazing to your window you are adding the U-value of

the glass itself as well as the U-value of the air in between Moreover the space between the

panes can be filled with gas instead of air Some gases have more thermal resistance than air

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 8 of 47

Argon Krypton and Sulfur Hexafluoride are the most common gases used for this purpose It

only adds a few extra dollars into the total price but adds a great value to the window‟s U-value

Figure 6 infrared picture for a home illustrates the amount of heat that flows through windows (represented in red)

Furthermore adding a microscopically thin layer of metallic oxide coating can

dramatically increase the window resistance The low ndash emittance (low-E) coating reflects the

radiative heat back into your home during the heating season and

reflects unneeded solar heat to the outside during the summer The

coating usually is applied to the interior face of a multi-pane window

to protect it from weather and cleaning conditions

Likewise the frame and the spacer which separate the multi-

pane (Figure 7) have a great impact on the overall U-Value of the

window Research shows that a double pane with a metal spacer has

almost the same U-factor as a single pane of glass (DOE 1997) Spacers made of aluminum and

steel are not recommended because of their low thermal performance The fiberglass and foam

Figure 7 window spacer

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 9 of 47

spacer are recommended because of their higher thermal performance

Window frames made of wood fiberglass and vinyl are better insulators than

metal or aluminum frames However some new metal and aluminum frames

are designed with internal insulation to break the metal thermal bridges

which increase resistance and improve performance (Figure 8)

Table 2 which is from the ASHRAE hand book shows representative

U-factors for glazing spacers and frames and their impact on the overall U-

Value

Table 2 U-Factors for glazing spacer and frame and its impact on the overall U-Value

Figure 8 Window frame with internal insulation to improve the window U-Value

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 10 of 47

Recommendation for selecting window U-value

To assign the correct U-value to your new windows make sure that the manufacturer

specifies this value for the whole window (glazing frame and spacer) not just the glazing value

The frame and spacer might increase the U-value of the window and decrease its efficiency

Avoid metal frames unless they have internal insulation to break the thermal bridges For

maximum insulating value wood vinyl and fiberglass are the suggested frame materials Single

pane is not permitted by most local building codes Double pane windows are the minimum

requirement Low-E coating with gas filled windows are recommended for their higher

insulating value with insignificant increase in cost Triple pane for south facing windows is

advisable In short the U-value should be no more than 04 at any window in order to ensure

mean higher insulation values and lower utility bills

Solar Gain

In winter windows can provide your home with free heating energy but can also cause

overheating during the summer Our goal is to maximize the winter solar gain (free heat) and

minimize the summer solar gain (overheating) The first part is easily achievable by having

bigger window sizes However this will also minimize the summer heat which is the dilemma

In fact solar transmission through windows accounts for 30 of the cooling requirements in

some regions (DOE 2008) The solar heat gain of a window depends on its solar heat gain

coefficient (SHGC) SHGC is a measure of the rate of solar heat flowing through a window

The orientation of the window has a great role in the total solar gain Figure 9 shows the

different heat flow through a 18rdquo clear single pane window in different orientations For

example when looking at figure 9 the south facing windows have potentially the highest most

beneficial solar heat gain during the winter season and has a lower gain during the summer time

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 11 of 47

thus south facing windows are the most important for solar heat gain High SHGC windows can

be used to maximize the winter gain and shades can be used to minimize the summer gain

Figure 9 solar heat gain through 18rdquo clear single pane window during the summer and winter sessions

In contrast the east and west windows are penalized twice (Figure 10) They lose solar

heat gain in winter and gain more solar heat in summer This is because the sun seldom shines

straight through east and west facing windows in the winter but shines powerfully on these

facades in the morning and afternoon during the summer West facing windows are mostly

challenging in summer time because they gain more heat during the afternoon (sunset) which is

the hottest time of the day Besides east and west windows are hardly shaded because the sun

angle is very low (Figure 11) Thus east and west windows must be minimized and carefully

designed A lower SHGC window can be used to improve heat-efficiency On the other hand

north facing windows are mostly useful for day lighting Unlike the others northern windows

provide a comfortable indirect light source which reduces the need for electric lights

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 12 of 47

Figure 10 The summer sun angle is higher than the winter sun angle The east and west sun angles are very low all

year round

Figure 11 Bigger incidence angle during the summer reflect most of the solar heat gain

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 13 of 47

Recommendation for selecting SHGC

Window SHGC should preferably be designated

according to the orientation South facing windows should

have a higher SHGC to maximize the winter gain This gain

will not usually result in overheating in the summer because of

the sun‟s greater incidence angle during the summer (Figure

12) East and west windows should have low SHGC because

they transmit solar heat gain during the summer Northern

windows don‟t face direct sunlight therefore there is no need to

spend extra money to improve north facing windows The

northern windows should be operable to provide cross

ventilation with south facing windows (Figure 13 and Table 3)

Table 3 Recommendation for U-Value and SHGC

Ventilation and Airtightness

The use of windows to ventilate your home is a very old architectural concept yet very

effective Nearly all historic buildings were ventilated naturally although many of these have

been used partially with mechanical systems Recent awareness of the environmental impacts

and costs of energy has encouraged natural ventilation Table 4 shows different window types

U-Value SHGC Recommendations

South Less than 032 Higher than 040 Higher SHGC to maximize solar gain

in winter

East and West Lower than 03 Double glazing and minimum sizes

North Operable to provide cross ventilation

Figure 12 Cross ventilation

Figure 13 Winter and summer sun angles

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 14 of 47

and their effective open area for ventilation Casement windows are effective for ventilation

because they direct the greatest fresh airflow into the living space when fully open

Infiltration is the unintended air change around the window through joints and cracks

This leakage accounts for about 10 of the energy used in the home (DOE) The tightness of the

window depends on the window quality as well as its proper installation A window with a

compressing seal such as a casement window is more

airtight than a regular sliding seal Air tightness rates

are given in cubic feet of air passing through a square

foot of window area per minute (cfm) The minimum

requirement is 037 cfmsf (Oregon Residential

Energy Code 2008- DOE) Operable windows can be

used during fall and spring to reduce the need of air

conditioning as well as provide ventilation they are

often specified to meet egress code requirements

Assign lower airtightness values at windy sites or other harsh climates in order to achieve

an ideal airtightness level and make sure that it is well insulated Check all the seals and edges

Table 4 representative window ventilation areas

Figure 14 apply caulk to all edges where window frame meet the wall

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 15 of 47

where the window frame meets the wall and carefully seal and caulk all joints and cracks (Figure

14)

Preventing condensation

Improving your windows will not only reduce your utility bills but will also save you a

lot on your maintenance expenses The energy efficient window can prevent condensation to

occur on the interior of your home which helps prevent dangerous issues such as mold Air

holds various amounts of water vapor which is correlated to the air temperature Cold air holds

less water vapor than hot air The amount of moister in the air is expressed in the ratio between

the amount of moisture in the air to the total amount of moisture that the air can hold This is

called relative humidity (RH) The RH increases when the air is being cooled because cold air

can hold less moisture than hot air making the existing moister level a higher percentage of what

the air can hold (Lechner 2009)

When RH reaches 100 the air can‟t hold any more moisture causing condensation

When moist air faces a cold surface like your old windows the air will be cooled which

decreases its ability to hold moisture causing water to condense on the surface of your window

similar to what happens to a cold glass of water in hot temperature Condensed water can

damage window frames sills and interior finishing In severe cases it might damage the

insulation and wood framing On the other hand air that comes in contact with your new energy-

efficient window is less likely to condense and cause those damages because window surface

will not be cold due to its higher insulation value

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 16 of 47

Daylighting

Windows can help you reduce the demand for artificial lighting but at the same time

they cause significant solar heat gain during summer months Simple solutions to reducing solar

heat gain such as tinted glazing or shades can reduce daylighting as well New glazing with

special low-E coating can provide better solar heat gain reduction with a slight loss of visible

light This characteristic is measured in visible transmittance (VT) VT measures how much light

flows through your window VT is an optical property that designates the quantity of visible light

transmitted It is expressed as a number between 0 and 1 Higher VT value means more

transmitted visible light through the window

The NFRC Label

The National Fenestration rating Council (NFRC) is a nonprofit private organization

who provides prospective window shoppers with a standard rating system between various

windows Figure 15 shows an NFRC label The most important numbers are the U-value and

SHGC

Figure 15 NFRC window label

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 17 of 47

Cost analysis

Now that we have covered the various methods and benefits of different characteristics of

windows for energy efficiency let‟s come up with a specific design for the average homeowner

in the New York metropolitan area and figure out the return-on-investment In order to optimize

energy efficiency we will replace the current south facing windows with a triple glazing low-E

coating windows with lower U-value and higher SHGC East and west facing window will be

replaced with double glazing low-E coating and gas filled windows with a lower U-factor and a

very low SHGC The northern windows will be replaced with operable double glazing windows

For this case study I will assume that all of the old windows are single pane with U-values of 05

and SHGC of 075

In a heating climate such as the New York Metropolitan area windows could be a major

source of heat loss However after applying the previous proposed solutions to your home we

can prevent the majority of the heat loss The table below (Table 5) illustrates the significant

savings in heating and cooling costs In order to calculate the non-solar heat flow I used the

formula

Q = U x A x HDD

where U is the difference between the old and new windows‟ U-value I assumed the old U-

value for all old windows to be 05 thus the difference was 025 for the southern windows 018

for the eastern and western windows and 01 for the northern windows A is the area of the

window and HDD is the heating degree day for New York City Table 1 In order to get the value

in Btuhour I multiplied the result by 24 (hourday) The total non-solar heat flow for all

windows was 371 $year

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 18 of 47

Table 5 Non-solar heat flow saving

Winter

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

HDD 4227 4227 4227 4227

Btuday 21135 15217 15217 8454

Btuhr 507240 365213 365213 202896

Number of window 4 2 2 3

Btu hr 2028960 730426 730426 608688

K Watt 594654 21408 21408 1784

Total Saving 130824 47097 47097 39247

Total Winter saving 26400 $year

Summer

South East West North

Difference in U-Value 025 018 018 01

Area 20 20 20 20

CDD 1712 1712 1712 1712

Btuday 8560 61632 61632 3424

Btuhr 205440 147917 147917 82176

Number of window 4 2 2 3

Btu hr 821760 295834 295834 246528

K Watt 240844 86704 86704 72253

Total Saving 529857 19075 19075 15896

Total Summer saving 107 $year

Total non-solar heat flow saving

371 $year

Now it is time to calculate the solar heat gain in the winter We can use the flowing

equation to do that Q= SHGC x A x SHGF

Where SHGC is the difference between the old and new windows Solar Heat gain Coefficient A

is the window area and SHGF is the solar heat gain factor which varies for each month and for

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 19 of 47

each location Table 6 shows SHGF for NYC From the table below the total savings from

capturing solar heat gain in the winter is $230year

Table 6 Calculating solar heat gain

Building Characteristic

Faccedilade Glass

Area

Different

SHGC old SHGC

(sf) -

075

North 30 036

East 10 056

West 10 056

South 40 022

Monthly Solar Radiation Values New York City (kBtusf)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4

East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10

South 30 29 33 29 27 24 27 30 33 34 25 23

Monthly Solar

Heat Gains (kBtu)

Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48

East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53

South 262 257 287 257 237 215 234 265 290 301 220 204

total heat gain

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr

Kwatt

$year

Total Winter

gain 3575

1048

230

From the previous calculation the total saving from non-solar heat flow and solar heat

gain is $601year Table 7 shows the estimated initial cost to replace your old windows with

more energy efficient windows Since most of the manufactures estimate their prices on a case

by case basis the proposed cost estimating was verbally verified from an experienced consultant

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 20 of 47

in the efficient window field The total estimated cost is $10980 Besides there will a maximum

amount of $200 tax credit for energy efficient windows

Table 7 Proposed cost estimation

South East and West North

Window type Triple glazing window Double glazing low-E

coating and gas filled

window

Double glazing window

Quantity 4 2 3

Specification Marvins 5‟ W x 4‟ H

triple-glazed window -

Wood Ultimate

Casement Collection

Marvin 4‟ W x 5‟ H

Low-E Argon Casement

Vinyl Window - 34Prime IG

minus LoĒ2 272R minus Argon minus

GBG

Marvin 4‟ W x 5‟ H

double pane Casement

Vinyl Window 34Prime IG

minus Air

U-value 025 032 040

SHGC 039 019 053

VT 047 044 056

Condensation

resistance

65 58 43

Supply $50 per SF

$100000 each

$38 per SF

$76000

$23 per SF

$46000

Installation $20000 each $17500 each $15000 each

Supply $ installation $120000 $93500 $61000

Total $480000 $187000 $244000

Total cost $ 10980

Graph 1 illustrates the payback time and the consumption per year The calculated

payback time for all windows improvement is about 18 years

1 2 3 4 5 6 7 8 9 10

4740 9480 14220 18960 23700 28440 33180 37920 42660 47400

11 12 13 14 15 16 17 18 19 20

52140 56880 61620 66360 71100 75840 80580 85320 90060 94800

21 22 23 24 25 26 27 28 29 30

99540 104280 109020 113760 118500 123240 127980 132720 137460 142200

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 21 of 47

31 32 33 34 35

146940 151680 156420 161160 165900

1 2 3 4 5 6 7 8 9 10

149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204

11 12 13 14 15 16 17 18 19 20

5630024 6043845 6457665 6871486 7285306 7699126 8112947 8526767 8940587 9354408

21 22 23 24 25 26 27 28 29 30

9768228 1018205 1059587 1100969 1142351 1183733 1225115 1266497 1307879 1349261

31 32 33 34 35

1390643 1432025 1473407 1514789 1556171

Graph 1 Payback time for window improvement

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouth window hellip

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 22 of 47

The initial investment might be an obstacle in today‟s economy $10000 for window

improvements might be a heavy burden especially for a low- and medium- house income There

are alternative pathways to finance your improvement Many manufacturers offer lease and

lease-purchase agreements Leasing an energy efficient product can significantly reduce the

upfront cost There are also many energy performance contracts where a contractor can install

and maintain your new windows in addition to providing you with the upfront cost An energy

performance contractor (EPC) guarantees you a specific amount of savings every year and in

return they are paid from the energy saving cost during the contract period which usually lasts

for about 10-15 years For more information about EPC visit wwwenergyservicescoalitionorg

In conclusion depending on orientation area and characteristic windows can account

for 10-30 or more of a code-compliant homes heating energy load Besides if windows are

designed and used appropriately they can also play a role in lighting and ventilation For all these

explanations windows have a great consequence on the energy efficiency and environmental

impact of your house

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 23 of 47

Passive Systems

Now that we have seen a variety of methods to enclose the thermal envelope we are now

going to propose ldquotier 2rdquo of the energy efficiency pyramid passive systems for heating cooling

and lighting The purpose of these systems are to aid the ldquoplug fillingrdquo thermal envelope

methods by optimizing the microclimate depending on the season sun angle prevailing winds

precipitation and any other microclimate advantages The passive system that will be described

in this section is ldquoLandscaping for energy efficiencyrdquo In this section we will explicitly describe

reasons for placement of plants and other landscape items on or around the home as they relate to

heating cooling and lighting and the quality of the microclimate that each provides Much like

the thermal envelope solutions we will discuss in terms of energy savings and return-on-

investment

Landscaping for Energy Efficiency

The New York City metropolitan area is well within the temperate climate zone (Figure

16) experiencing four distinct seasons Selection and placement of landscape plants are critical

to this exercise in taking advantage and avoiding what these seasons have to offer Ultimately in

the summer months we want to optimize the prevailing winds to allow for natural ventilation and

cooling and shade the sun to avoid passive solar heat in order to reduce air conditioning usage

lowering your electric bill Alternatively in the winter months one wants to block cold winds

and optimize sunlight for solar hear gain in order to lower your heating bill Theoretically in all

seasons we want to optimize light which may be difficult in the summer months without solar

heat gain Evapotranspiration is another microclimate element we want to optimize to aid in

cooling during the summer months

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 24 of 47

Figure 16 Climate zones of the United States courtesy DOE

Winter

Winter in New York City and the northern United States in general can be rather harsh

Temperatures can go as low as -20 to -10 degrees Fahrenheit (Lechner 09) When adding the

wind chill factor temperatures can feel as low as -50 degrees Fahrenheit (Wheeling Jesuit

University 2004) These winds tend to come from the Northwest during the winter months

typically about half of the year (NYS Climate Office 2011) Optimal placement of evergreen

trees and shrubs a short distance from the north to north west faccedilade of your home can

potentially eliminate the wind chill factor as it relates to home heating As seen in figure 17 a

small amount of wind reduction can have a huge effect on infiltration heat loss In fact cold air

infiltration in the Northeast is responsible for 13 winter heat loss in the average home and up to

frac12 on windy days (Lechner 09)

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 25 of 47

Figure 17 Reduction in heat loss from reduction in wind courtesy DOE

When placing evergreen trees and shrubs it is important to follow some simple

guidelines in order to appropriately direct the wind away from your home The evergreen mass

should be a dense thicket of trees and shrubs in order to achieve the appropriate heights widths

and porosity of the planting The windbreak should be placed away from your home

approximately two to five times the mature height of the evergreen trees (DOE 1995) This will

give your home optimal wind protection by pushing it up and over your home (Figure 18) This

distance will also allow the wind that does make it through the windbreak to dissipate by the

time it reaches the faccedilade Placing too far away may allow the wind that is intended to get

pushed over the home to dip back down into the faccedilade you‟re trying to avoid (Figure 19) Try

to make the windbreak as continuous as possible with low-lying branches that reach the ground

Gaps in windbreaks may result in an opposite effect increasing wind velocity This is a method

that we will want to optimize in the summer but definitely not in the winter (Figure 20) The

addition of a temporary trellis with evergreen vines may temporarily fill those gaps until the

larger trees grow enough to appropriately infill the gaps The windbreak width should also be at

least ten times the height to optimize the wind shadow for the northern faccedilade of your home

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 26 of 47

Figure 18 Windbreaks push wind over the home courtesy DOE

Figure 19 Distance as a function of height of windbreak courtesy Harris

Figure 20 Gaps in a windbreak actually increase wind velocity courtesy Lechner

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 27 of 47

When selecting species of evergreens to plant you typically want to choose fast growing

pest resistant trees and shrubs You want fast-growing species to optimize the windbreak

capabilities and pest resistant to avoid attracting pests to your home Table 9 shows a list of

evergreen tree shrub and vine species that may be used for the purposes of a windbreak

Table 8 Evergreen plant suitable as windbreaks

Latin Name Common Name Growth Rate Pest Resistance Mature Height

Picea abies Norway Spruce Med to Fast High 40 to 60‟

Pinus resinosa Red Pine Med to Fast Med 50 to 100‟

Juniperus virginiana Eastern Red

Cedar

Slow to Med High 60‟

Thuja standishii X

plicata bdquoGreen Giant‟

Green Giant

Arborvitae

Fast High 50 to 60‟

Cryptomeria japonica

var sinensis

bdquoRadiacans‟

Radicans

Cryptomeria

Fast High 30 to 40‟

Picea glauca var

densata

Black Hills

Spruce

Med High 30 to 60‟

Ilex opaca American Holly Slow High 30‟

Taxus cuspidata Japanese Yew Slow High 8 to 10‟

Hendera helix English Ivy Fast Very High NA

Lonicera

sempervirens

Coral

Honeysuckle

Fast High NA

Now that we‟ve discussed blocking the prevailing northwesterly winds with an

appropriate windbreak planting it is equally important to optimize the winter sun angle along the

south faccedilade of your home Hopefully your neighbor‟s house fence or trees are not impeding

upon this angle The ldquosolar access boundaryrdquo is a conical surface showing the sunlight access to

a building or specific site on December 21 from 9 AM to 3 PM (Figure 21) If any buildings

trees fences etc protrude through this boundary the building you are trying to optimize for

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 28 of 47

winter sunlight will have a shadow cast upon it Table 10 and Figure 22 reveal how tall an object

can be related to the sun angle For example when looking at Table 10 New York is

approximately at latitude 40 which when transferring the data to Figure 22 means that the

tallest tree at mature height at point L that could be planted is 10‟ and cannot be planted any

closer than 20‟ so as not to block the winter solstice sun at 1200 noon At 300 PM the tallest

tree at point B could be 10‟ but has to be planted at least 47 feet away Perhaps a nice flowering

shrub is more appropriate for this location with small trees further to the south where height is

not as much of an issue A flowering tree such as Cercis Canadensis that never grows above 20‟

may be appropriate for points D or N (Lechner 2009)

Figure 21 Solar Access Boundary courtesy Lechner

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 29 of 47

Figure 22 Maximum height objects can reach as they relate to the Solar Access Boundary courtesy Lechner

Table 9 Distance in feet from building courtesy Lechner

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 30 of 47

If existing mature trees already exist within the ldquosolar access boundaryrdquo you may want to

consider pruning the lower limbs to allow the winter sun to protrude beneath the main crown of

the tree which will be of considerable benefit in the summer when the dense foliage blocks the

hot summer sun (Figure 23) Keep in mind that the distances and heights given on Table 10 and

Figure 22 assume that the lot is flat If the land slopes uphill from home from the south faccedilade

you will need to subtract that difference in elevation from these heights Alternatively if the

land slopes downhill you can plant taller species

Figure 23 Prune lower branches on south facade to allow for winter sun courtesy Lechner

In New York State the average home consumes approximately 76000 cubic feet of

natural gas each year for home heating (EIA 2011) Assuming that all of it is consumed in the

six month period from mid-October to mid-April 12667 cubic feet of natural gas is consumed

each month Studies have found that 25 percent of home heating costs can be reduced by

planting suitable windbreaks Later on we will discuss the cost savings associated with this

reduction but it can feel rewarding to offset 3167 cubic feet of natural gas consumption while

beautifying your lot at the same time

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 31 of 47

Summer

As mentioned earlier during the summer months in the New York City metropolitan

area southwesterly winds are to be optimized for cooling while sunlight is shaded to avoid

passive solar heat Evapotranspiration may also be optimized for a cooling effect In the United

States air conditioning usage accounts for 16 of all residential electric energy use (EIA 2011)

In New York State 78 of all residential electric energy use is from air conditioning (EIA

2011) Of the households in New York State that do have air conditioning their air conditioning

consumption is 26 percent of their total which is actually 52 percent considering air conditioning

is only used for half the year in a temperate climate That accounts for approximately 1552

KWhs per household per year based on 47 million households (EIA 2011) When these units

are shaded and the southern faccedilade is optimized for shade air-conditioning consumption can be

reduced anywhere from 15 to 50 (MSU Extension 2001) In fact shading an air conditioning

unit alone can increase its efficiency by 10 (DOE 2011)

When placing trees for shading purposes it is important to follow simple guidelines in

order to optimize shading while at the same time maintain the winter sun angle As mentioned

earlier if tall deciduous trees exist along your southern faccedilade it is important to prune the limbs

so as to not interfere with the ldquosolar access boundaryrdquo between 9 AM and 3 PM which is when

80 of solar radiation is gained in the winter months (Lechner 2009) Consult a licensed

arborist to perform this task An incorrect prune on the wrong limb could be detrimental to the

mature tree Also refer to Figure 24 the winter tree shadow template to get a general idea of

how your mature tree will shade your home For example in New York a tree that is directly

southeast from your home will cast a shadow on it up to five times the height of the tree and

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 32 of 47

about half that much during the summer months Trees tend to be superior to shading than man-

made structures due to the fact that they do not absorb and radiate heat (Figure 25)

Figure 24 Winter tree shadow template courtesy Lechner

Figure 25 Shading from trees vs man-made structures courtesy Lechner

If you desire to plant a deciduous tree along the southern faccedilade keep in mind it may

take several years before you reap the energy saving benefits from shading In fact you may be

doing the reverse considering that even without leaves deciduous trees block 30 to 60 of

winter sunlight Some species such as oaks tend to hold onto their leaves well into the winter

months further blocking much need winter sun Select a fast growing oval to round shaped and

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 33 of 47

high branched tree Red Maples (Acer rubrum) and London Plane Trees (Platanus X acerifolia)

would be a good choice Perhaps a trellis with a deciduous climbing vine such as Parthenocecis

quinquifolia can provide the much needed shading to conserve air-conditioning consumption as

an alternative to plating a tree Vines also release water vapor through evapotranspiration from

the leaves creating a cooling effect Smaller trees with crowns lower to the ground may be

desired along the western faccedilade for late afternoon shading when it‟s the warmest These trees

don‟t interfere with the winter sun angle and greatly aid in summer cooling

Optimizing the prevailing southwesterly winds during the summer in New York is

equally as important as shading As discussed earlier in the ldquoWinterrdquo section wind velocity is

greatly increased between gaps and at the end of windbreaks One way to increase wind speed is

to either funnel the wind via shrubs toward your home or plant trees with high canopies to allow

for cool summer breezes to flow underneath (Figures 26 and 27) Planting flowing trees in this

location can have the additional benefit of the wind transporting the fragrant aromas you‟re your

home Shrubs may also be sited off of the western faccedilade to optimize the wind (Figure 28) If

your home has a roof vent the southwest winds will enter your home at ground level and push

warmer air through the roof cooling the home

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 34 of 47

Figure 26 Summer breezes are funneled toward the home via shrubs courtesy Sustainable Energy Authority Victoria

Figure 27 Summer breezes are funneled under high canopy trees courtesy Lechner

Figure 28 Placement of shrubs can deflect wind toward your home courtesy Lechner

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 35 of 47

All Seasons

As mentioned earlier natural light is to be optimized year round in order to aid in

reducing your monthly bills and energy consumption In New York State lighting accounts for

157 percent of electricity usage in the average household which is approximately 940 KWh per

year based on 71 million households (EIA 2011) The obvious way to accomplish this is to

install large windows and skylights along the south facade of your home A less obvious method

is to position plantings trellises and reflective pavements in order to optimize interior light In

order to optimize this light in the winter be sure to obviate obstructions and avoid planting

within the ldquoSolar Access Boundaryrdquo The low sun angle during the winter months will allow

ample light to penetrate your home During the summer months shading is to be optimized

while optimizing light This can be rather tricky One way to accomplish this goal is with

reflected light As seen in Figure 29 light reflected off of the ground actually penetrate further

into your home than direct sunlight in the summer without gaining too much solar heat gain A

light colored pavement will improve this reflectivity The addition of a trellis with a deciduous

vine will also aid in cooling your home while optimizing this reflectivity

Figure 29 reflected light penetrates deeper into your home than direct sunlight courtesy Lechner

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 36 of 47

Plants also improve the quality of light that enters your home by reducing glare A tree

with a light to moderate foliage such as Gleditsia triacanthos var inermis the Common

Thornless Honeylocust is a good example of one of these trees

One vernacular architectural example that optimizes light and temperature with the

methods described above is the Pennsylvania Bank Barn (Figure 30) This barn was introduced

to Pennsylvania in the 19th century by German immigrants for cattle grazing With this design

the cattle that reside in the basement benefit from the solar heat gain and light in the winter while

benefiting from the shade and reflected light in the summer Today this concept can be obtained

by proper placement of trees and trellises

Figure 30 Pennsylvania Bank Barn

Cost Analysis

Now that we have discussed the techniques and benefits of landscaping for energy

efficiency it‟s time to design your landscape and evaluate your associated costs to come up with

your return-on-investment First let‟s come up with a landscape design that optimizes energy

efficiency for the New York metropolitan area (Figure 31) In this design we are optimizing for

winter conditions by planting evergreen trees shrubs and trellises with evergreen vines off of

the north facade of the home We are also going to bring in a tree pruning company to spend a

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 37 of 47

day pruning the lower branches off of the two existing trees along the southern facade This will

allow us to optimize the ldquoSolar Access Boundaryrdquo during the winter while providing shade in the

summer Also for the summer we are going to plant high canopy flowering trees and a few

shrubs along the eastern and western facades to allow for breezes We are also going to

construct a trellis along the southern facade which will hold a deciduous vine to allow for

shading and reflective light These costs are listed in Table 11

Figure 31 Landscape design that optimizes energy efficiency for New York City Metropolitan Area

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 38 of 47

Table 10 Landscape improvement costs

Item Quantity Supply Installation Total

Picea abies (8-10‟) 3 $300 EA $155 EA $136500

Juniperus virginiana

(8-10‟)

2 $250 EA $124 EA $74800

Illex opaca (6-7‟) 2 $250 EA $370 EA $124000

Cornus florida (3-

35rdquo caliper)

5 $250 EA $375 EA $312500

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $420 EA $335000

Hydrangea

quercifolia (3-4‟)

5 $65 EA $80 EA $72500

Lonicera

sempervirens

24 $150 EA $035 EA $4440

Clematis (1 Gallon) 8 $30 EA $10 EA $32000

Free standing trellis 3 $169 EA $0 $50700

Porch trellis 1 $108671 $174240 $282911 ^

Tree pruning 1 $120000

Total $1545351

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot

Prices courtesy Almstead Tree Service

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales tax

installation at $30HrLaborer 3 person crew for 2 days plus 21 overhead and profit

As discussed earlier natural gas consumption in the winter and electricity consumption in

the summer can be drastically reduced with landscaping techniques The winter gas bill can be

reduced 25 percent in the winter while air conditioning costs can be reduced 15 to 50 percent in

the summer The electricity bill can also be reduced somewhat year round from reduced lighting

costs For the purposes of this scenario let‟s assume we save 25 percent monthly on air

conditioning for six months out of the year and 25 percent year round on lighting Table 12

summarizes the cost and energy savings for a typical New York resident (EIA 2011 Cenhud

2011)

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 39 of 47

Table 11 Cost and energy saving scenario for a typical New York household

Service Consumption

mo

Avg

monthly

bill

Reduction Total

Months

Energy saved

Month

Cost savings

Month

Natural

Gas

12667 CF $246 25 6 3167 CF $6150

Electricity 500 KWh $9648

Elect AC 260 KWh $5017 25 6 65 KWh $1254

Elect

Lighting

785 KWh $1515 25 12 1963 KWh $379

As shown in Graph 2 assuming the owner took out a loan at 5 interest the return-on-

investment for this landscape improvement is 35 years 8 months

Graph 2 Return-on-investment for supply and installation of landscape design

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 40 of 47

This length of time may not give the homeowner an incentive to make this investment

especially since the payback time is longer than a typical 30 year mortgage This in this

author‟s opinion is due to high installation costs in the New York City region In the above

estimate $30hour was assumed which is actually less than prevailing wage as indicated by the

labor laws for public work Since this is residential work approximately half of the prevailing

wage cost of $65hour for a union laborer was assumed which is still drastically higher than

other cities in the United States As a homeowner looking to save on energy costs you may elect

to reduce this return-on-investment by either choosing a simpler less expensive design or elect

to perform the work yourself

The below cost estimate and graph assume only material costs for the same design with

the exception of tree pruning which should be done by a licensed arborist The return-on-

investment as seen in table 13 and graph 3 is now 15 years which gives a much better energy

conservation incentive

Table 12 Return-on-investment for supply of landscape design materials

Item Quantity Supply Total

Picea abies (8-10‟) 3 $300 EA $90000

Juniperus virginiana (8-

10‟)

2 $250 EA $50000

Illex opaca (6-7‟) 2 $250 EA $50000

Cornus florida (3-35rdquo

caliper)

5 $250 EA $125000

Magnolia virginiana

glauca (10-12‟)

5 $250 EA $125000

Hydrangea quercifolia (3-

4‟)

5 $65 EA $32500

Lonicera sempervirens 24 $150 EA $3600

Clematis (1 Gallon) 8 $30 EA $24000

Free standing trellis 3 $169 EA $50700

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 41 of 47

Porch trellis 1 $108671 $108671 ^

Tree pruning 1 $120000

Total $689471

Prices courtesy Home amp Garden Kraft Inc

Prices courtesy Home Depot Inc

Prices courtesy Almstead Tree amp Shrub Care Co

^ Porch trellis based on materials (dimensional lumber stain fasteners concrete NYC sales

tax)

Graph 3 Return-on-investment supply costs only

Market Incentives

Throughout this manual we have introduced various methods for energy conservation

and return-on-investment via sealing the thermal envelope and introducing the passive system of

landscaping for energy efficiency Tax incentives and other market tools may help us achieve a

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 42 of 47

sooner return-on-investment which gives an incentive for energy efficiency as well as spark the

local sales market for energy efficient products The federal government introduced the ldquoTax

Incentive Assistance Project (TIAP) back in 2009 which granted a tax credit for 30 of

qualifying energy efficient products for the thermal envelope of existing and new homes with a

cap of $150000 If this incentive was applicable to landscape design products ( ie trees

shrubs trellises etc) the above return-on-investment would be reduced to 12 years 6 months

Perhaps it may be more cost effective to purchase portions of your landscape design

incrementally in order to qualify for the tax credit each year This may also obviate the need to

take out a loan thus saving even more in the long run New York State also provides certain

incentives at getenergysmartorg

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 43 of 47

References

Cost of Low-E Glass (ie per Square Foot) - Windows Forum - GardenWeb That Home Site

Forums - GardenWeb Web 26 May 2011

lthttpthsgardenwebcomforumsloadwindowsmsg0210501621850html6gt

Energy Tax Credit 2011 ndash Not What It Used to Be Darwins Money mdash Financial Evolution for

the Masses Web 26 May 2011 lthttpwwwdarwinsmoneycomenergy-tax-credit-2011gt

Heating amp Cooling Degree Days - Free Worldwide Data Calculation Web 26 May 2011

lthttpwwwdegreedaysnetgt

How to Select Windows for Energy Efficiency and Style - a Knol by Daniel Snyder Knol - a

Unit of Knowledge Share What You Know Publish Your Expertise Web 26 May 2011

lthttpknolgooglecomkdaniel-snyderhow-to-select-windows-for-energy19yp2ug8iz12372gt

Push Out French Casement - Marvin Windows and Doors Marvin Windows and Doors -

Marvin Windows and Doors Web 26 May 2011 lthttpwwwmarvincomwindowsfrench-

push-out-casement-windowssizes-performance-and-specsgt

Understanding Energy-Efficient Windows - Fine Homebuilding Article Fine Homebuilding

Get Expert Home Construction Tips Tool Reviews Remodeling Design and Layout Ideas House

Project Plans and Advice for Homeowners Web 26 May 2011

lthttpwwwfinehomebuildingcomhow-toarticlesunderstanding-energy-efficient-

windowsaspxgt

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 44 of 47

Watts (W) to BTUhr Conversion Calculator - RapidTablescom Online Reference amp Tools -

RapidTablescom Web 26 May 2011

lthttpwwwrapidtablescomconvertpowerWatt_to_BTUhtmgt

Welcome to the Efficient Windows Collaborative Web Site Web 26 May 2011

lthttpwwwefficientwindowsorggt

Lechner Norbert Heating Cooling Lighting Sustainable Design Methods for Architects New

York John Wiley amp Sons Inc 2009 295-341

Harris Charles W and Nicholas T Dines Time-Saver Standards for Landscape Architecture

Second Edition New York McGraw-Hill 1998

Tuckahoe Nurseries Inc 2010-2011 Catalogue Tuckahoe NJ 2010

Wettstien Chris E (Owner of Home amp Garden Kraft Milford NJ) Interview by author In-

person interview of this local landscape contractor with cost estimate Milford NJ May 16

2011

Almstead Ken (CEO of Almstead Tree and Shrub Care Company) Interview by author

Telephone interview of this local tree care specialist with cost estimate New York NY May

16 2011

Department of Energy ldquoLandscaping for Energy Efficiencyrdquo April 1995

httpwwwnrelgovdocslegostiold16632pdf

Homer TLC Inc ldquoThe Home Depot Shop all Departmentsrdquo Accessed May 19 2011

httpwwwhomedepotcomcm_mmc=SEM|RPM|ST_Branded|GGL_2881ampskwcid=TC|13614|

home20depot||S|e|6468551964

Page 45 of 47

Michigan State University Extension ldquoEnergy Facts Landscaping for Energy Conservation ndash

Benefits and Important Considerationsrdquo July 20 2001

httpweb1msuemsuedumsueiacenergyconservation-landscape_benefitspdf

US Energy Information Administration ldquoNew York Household Electricity Report ndash Tablerdquo

January 30 2006 wwweiadoegovemeurepsenduseer01_ny_tab1html

Central Hudson Gas amp Electricity Corporation ldquoNew York State Typical Bill American Gas

Association Surveyrdquo June 30 2010 wwwcenhudcomratesres_gashtml

Sustainable Energy Authority ndash Victoria ldquoSustainable Energy Info ndash Landscape Designrdquo

Accessed May 14 2011

httpwwwsustainabilityvicgovauresourcesdocumentsLandscape_designpdf

Central Hudson Gas amp Electricity Corporation ldquoNew York State Typical Bill Edison Electric

Institute Bill Survey Residential July 1 2010 wwwcenhudcomratesres_electhtml

New York State Climate Office ldquoThe Climate of New Yorkrdquo Accessed May 14 2011

wwwnysccascornelleduclimate_of_nyhtml

Energy Information Administration ldquoRegional Energy Profiles US Household Electricity

Reportrdquo July 14 2005 wwweiadoegovemeurepsenduseer01_us_figshtml1

Energy Information Administration ldquoNatural Gas Consumption and Expenditures in US

Households by End Uses and Census Region 2001rdquo 2001

wwweiagovemeurecsbyfuels2001byfuel_ngpdf

Bankrate Inc ldquoLoan Calculator and Amortizationrdquo Accessed May 19 2011

httpwwwbankratecomcalculatorsmortgagesloan-calculatoraspx

Page 46 of 47

Tax Incentives Assistance Project (TIAP) ldquoGeneral Informationrdquo Accessed May 19 2011

httpenergytaxincentivesorggeneralincentivesphp

New York State Energy Research and Development ldquoHome pagerdquo Accessed May 19 2011

httpwwwgetenergysmartorg

Wheeling Jesuit University ldquoTemperature Team Graph 3 ndash New York CItyrdquo 2004

httpwwwe-missionsnetweather2pdftempgraph3pdf

I

South East West NorthArea 20 20 20 20SupplySF 50 38 38 23Supply 1000 760 760 460Installation 200 175 175 150total costWindow 1200 935 935 610 of windows 4 2 2 4Total cost 4800 1870 1870 2440

Initial investment 10980

New SHGC

Building CharacteristicsFaccedilade Glass Area SHGC old SHGC

(sf) - 075North 30 036East 10 056

West 10 056South 40 022Roof

Monthly Solar Radiation Values New York City (kBtusf)Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10South 30 29 33 29 27 24 27 30 33 34 25 23

Horizontal 18 23 36 44 55 56 58 51 40 31 18 15

Monthly Solar Heat Gains (kBtu)Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53South 262 257 287 257 237 215 234 265 290 301 220 204

Horizontal

total heat gain440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr Kwatt SavingWinter gain 3575 1048 231Summer Gain 3641 1067 235

window area HDD CDD $KwattWinter 20 4227 1712 022

South East West NorthDifference in U-Value 025 018 018 01 $Kwatt - gas

Area 20 20 20 20 0125

HDD 4227 4227 4227 4227Btuday 21135 152172 152172 8454Btuhr 507240 365213 365213 202896Number of window 4 2 2 3Btu hr 2028960 730426 730426 608688Kwatt 594654 214075 214075 178396Total Saving 130824 470966 470966 392472 Winter Non-Sloar saving

264264309Summer Winter Solar Saving

South East West North 230500636

Difference in U-Value 025 018 018 01Area 20 20 20 20 Total Winter Saving

CDD 1712 1712 1712 1712 494764946

Btuday 8560 61632 61632 3424Btuhr 205440 147917 147917 82176Number of window 4 2 2 3Btu hr 821760 295834 295834 246528K Watt 240844 867039 867039 722532Total Saving 529857 190749 190749 158957

Summer Non-Sloar saving107031109

Total Saving601796055

Inistial investment 10980Total saving 6017961 $yearTax credit 200

Gas bill 1800 $yearElectricity 2940 $year

Total current bill 4740 $yeartotal new bill 4138204 $year

year 1 2 3 4 5 6 7 8 9 10 11 12 13cost 4740 9480 14220 18960 23700 28440 33180 37920 42660 47400 52140 56880 61620

year 1 2 3 4 5 6 7 8 9 10 11 12 13new cost 149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204 5630024 6043845 6457665

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouthhellip

14 15 16 17 18 19 20 21 22 23 24 25 26 2766360 71100 75840 80580 85320 90060 94800 99540 104280 109020 113760 118500 123240 127980

14 15 16 17 18 19 20 21 22 23 24 25 26 276871486 7285306 7699126 8112947 8526767 8940587 9354408 9768228 1018205 1059587 1100969 1142351 1183733 1225115

Years 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Without landscape improvements$000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512 $3423888 $3687264 $3950640 $4214016 $4477392

With landscape improvements$1063200 $1277604 $1492008 $1706412 $1920816 $2135220 $2349624 $2564028 $2778432 $2992836 $3207240 $3421644 $3636048 $3850452 $4064856 $4279260 $4493664 $4708068

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

Years

Years Without landscape improvements With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements

New SHGC

Building CharacteristicsFaccedilade Glass Area SHGC old SHGC

(sf) - 075North 30 036East 10 056

West 10 056South 40 022Roof

Monthly Solar Radiation Values New York City (kBtusf)Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 4 6 9 10 15 15 16 12 9 7 5 4East 10 15 22 27 32 31 35 31 25 19 11 9

West 13 15 23 25 30 30 32 27 23 20 12 10South 30 29 33 29 27 24 27 30 33 34 25 23

Horizontal 18 23 36 44 55 56 58 51 40 31 18 15

Monthly Solar Heat Gains (kBtu)Faccedilade Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

North 48 65 99 110 161 164 175 134 96 79 55 48East 59 85 122 149 179 176 195 174 142 105 64 50

West 71 82 126 140 170 170 179 153 131 112 66 53South 262 257 287 257 237 215 234 265 290 301 220 204

Horizontal

total heat gain440 489 635 656 748 725 783 725 659 597 405 355

Kbtuhr Kwatt SavingWinter gain 3575 1048 231Summer Gain 3641 1067 235

window area HDD CDD $KwattWinter 20 4227 1712 022

South East West NorthDifference in U-Value 025 018 018 01 $Kwatt - gas

Area 20 20 20 20 0125

HDD 4227 4227 4227 4227Btuday 21135 152172 152172 8454Btuhr 507240 365213 365213 202896Number of window 4 2 2 3Btu hr 2028960 730426 730426 608688Kwatt 594654 214075 214075 178396Total Saving 130824 470966 470966 392472 Winter Non-Sloar saving

264264309Summer Winter Solar Saving

South East West North 230500636

Difference in U-Value 025 018 018 01Area 20 20 20 20 Total Winter Saving

CDD 1712 1712 1712 1712 494764946

Btuday 8560 61632 61632 3424Btuhr 205440 147917 147917 82176Number of window 4 2 2 3Btu hr 821760 295834 295834 246528K Watt 240844 867039 867039 722532Total Saving 529857 190749 190749 158957

Summer Non-Sloar saving107031109

Total Saving601796055

Inistial investment 10980Total saving 6017961 $yearTax credit 200

Gas bill 1800 $yearElectricity 2940 $year

Total current bill 4740 $yeartotal new bill 4138204 $year

year 1 2 3 4 5 6 7 8 9 10 11 12 13cost 4740 9480 14220 18960 23700 28440 33180 37920 42660 47400 52140 56880 61620

year 1 2 3 4 5 6 7 8 9 10 11 12 13new cost 149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204 5630024 6043845 6457665

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouthhellip

14 15 16 17 18 19 20 21 22 23 24 25 26 2766360 71100 75840 80580 85320 90060 94800 99540 104280 109020 113760 118500 123240 127980

14 15 16 17 18 19 20 21 22 23 24 25 26 276871486 7285306 7699126 8112947 8526767 8940587 9354408 9768228 1018205 1059587 1100969 1142351 1183733 1225115

Years 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Without landscape improvements$000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512 $3423888 $3687264 $3950640 $4214016 $4477392

With landscape improvements$1063200 $1277604 $1492008 $1706412 $1920816 $2135220 $2349624 $2564028 $2778432 $2992836 $3207240 $3421644 $3636048 $3850452 $4064856 $4279260 $4493664 $4708068

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

Years

Years Without landscape improvements With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements

window area HDD CDD $KwattWinter 20 4227 1712 022

South East West NorthDifference in U-Value 025 018 018 01 $Kwatt - gas

Area 20 20 20 20 0125

HDD 4227 4227 4227 4227Btuday 21135 152172 152172 8454Btuhr 507240 365213 365213 202896Number of window 4 2 2 3Btu hr 2028960 730426 730426 608688Kwatt 594654 214075 214075 178396Total Saving 130824 470966 470966 392472 Winter Non-Sloar saving

264264309Summer Winter Solar Saving

South East West North 230500636

Difference in U-Value 025 018 018 01Area 20 20 20 20 Total Winter Saving

CDD 1712 1712 1712 1712 494764946

Btuday 8560 61632 61632 3424Btuhr 205440 147917 147917 82176Number of window 4 2 2 3Btu hr 821760 295834 295834 246528K Watt 240844 867039 867039 722532Total Saving 529857 190749 190749 158957

Summer Non-Sloar saving107031109

Total Saving601796055

Inistial investment 10980Total saving 6017961 $yearTax credit 200

Gas bill 1800 $yearElectricity 2940 $year

Total current bill 4740 $yeartotal new bill 4138204 $year

year 1 2 3 4 5 6 7 8 9 10 11 12 13cost 4740 9480 14220 18960 23700 28440 33180 37920 42660 47400 52140 56880 61620

year 1 2 3 4 5 6 7 8 9 10 11 12 13new cost 149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204 5630024 6043845 6457665

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouthhellip

14 15 16 17 18 19 20 21 22 23 24 25 26 2766360 71100 75840 80580 85320 90060 94800 99540 104280 109020 113760 118500 123240 127980

14 15 16 17 18 19 20 21 22 23 24 25 26 276871486 7285306 7699126 8112947 8526767 8940587 9354408 9768228 1018205 1059587 1100969 1142351 1183733 1225115

Years 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Without landscape improvements$000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512 $3423888 $3687264 $3950640 $4214016 $4477392

With landscape improvements$1063200 $1277604 $1492008 $1706412 $1920816 $2135220 $2349624 $2564028 $2778432 $2992836 $3207240 $3421644 $3636048 $3850452 $4064856 $4279260 $4493664 $4708068

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

Years

Years Without landscape improvements With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements

Inistial investment 10980Total saving 6017961 $yearTax credit 200

Gas bill 1800 $yearElectricity 2940 $year

Total current bill 4740 $yeartotal new bill 4138204 $year

year 1 2 3 4 5 6 7 8 9 10 11 12 13cost 4740 9480 14220 18960 23700 28440 33180 37920 42660 47400 52140 56880 61620

year 1 2 3 4 5 6 7 8 9 10 11 12 13new cost 149182 1905641 2319461 2733282 3147102 3560922 3974743 4388563 48024 5216204 5630024 6043845 6457665

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35 40

Co

nsu

mp

tio

n

Years Consumption withouthhellip

14 15 16 17 18 19 20 21 22 23 24 25 26 2766360 71100 75840 80580 85320 90060 94800 99540 104280 109020 113760 118500 123240 127980

14 15 16 17 18 19 20 21 22 23 24 25 26 276871486 7285306 7699126 8112947 8526767 8940587 9354408 9768228 1018205 1059587 1100969 1142351 1183733 1225115

Years 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Without landscape improvements$000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512 $3423888 $3687264 $3950640 $4214016 $4477392

With landscape improvements$1063200 $1277604 $1492008 $1706412 $1920816 $2135220 $2349624 $2564028 $2778432 $2992836 $3207240 $3421644 $3636048 $3850452 $4064856 $4279260 $4493664 $4708068

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

Years

Years Without landscape improvements With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements

14 15 16 17 18 19 20 21 22 23 24 25 26 2766360 71100 75840 80580 85320 90060 94800 99540 104280 109020 113760 118500 123240 127980

14 15 16 17 18 19 20 21 22 23 24 25 26 276871486 7285306 7699126 8112947 8526767 8940587 9354408 9768228 1018205 1059587 1100969 1142351 1183733 1225115

Years 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Without landscape improvements$000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512 $3423888 $3687264 $3950640 $4214016 $4477392

With landscape improvements$1063200 $1277604 $1492008 $1706412 $1920816 $2135220 $2349624 $2564028 $2778432 $2992836 $3207240 $3421644 $3636048 $3850452 $4064856 $4279260 $4493664 $4708068

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

Years

Years Without landscape improvements With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Without landscape improvements$000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512 $3423888 $3687264 $3950640 $4214016 $4477392

With landscape improvements$1063200 $1277604 $1492008 $1706412 $1920816 $2135220 $2349624 $2564028 $2778432 $2992836 $3207240 $3421644 $3636048 $3850452 $4064856 $4279260 $4493664 $4708068

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

Years

Years Without landscape improvements With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements

Years 0 1 2 3 4 5 6 7 8 9 10 11 12

Without landscape improvements $000 $263376 $526752 $790128 $1053504 $1316880 $1580256 $1843632 $2107008 $2370384 $2633760 $2897136 $3160512

With landscape improvements $780660 $995064 $1209468 $1423872 $1638276 $1852680 $2067084 $2281488 $2495892 $2710296 $2924700 $3139104 $3353508

$000

$1000000

$2000000

$3000000

$4000000

$5000000

$6000000

$7000000

$8000000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Years

Without landscape improvements

With landscape improvements