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EGEE 102 Energy Conservation
And Environmental Protection
Home Heating Basics
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EGEE 102 2
National Average Home
Energy Costs
9%
33%
14%
44%
Heating and Cooling
Refrigrator
Lighting, Cooking and
other Appliances
Water Heating
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EGEE 102 3
Why do we need
Heating?
70 'F
Furnace
30 F
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EGEE 102 4
Typical Heat losses-
Conventional House
5% through ceilings
16%throughwindows
1% throughbasement floor
17% through
frame walls
3% through door
38% through cracksin walls, windows,and doors
20%through
basementwalls
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EGEE 102 5
Heat Transfer
Conduction
Convection
Radiation
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EGEE 102 6
Conduction
Energy is conducted down
the rod as the vibrations of
one molecule are passed
to the next, but there
is no movement of energetic
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Convection
Energy is carried by thebulk motion of the fluid
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Radiation
Energy is carried byelectromagnetic waves.
No medium is required
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Degree Days
Index of fuel consumption indicating howmany degrees the mean temperature fell
below 65 degrees for the day Heating degree days (HDD) are used to
estimate the amount of energy required forresidential space heating during the cool
season. Cooling degree days (CDD) are used to
estimate the amount of air conditioning usage
during the warm season
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How do we calculate
HDD? HDD = Tbase - Ta
if Ta is less than Tbase
HDD = 0
if Ta is greater or equal to Tbase
Where: Tbase = temperature base, usually
65 F Ta = average temperature, Ta =(Tmax + Tmin) / 2
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Heating Degree Days
Calculate the number of degree daysaccumulated in one day in which the
average outside temperature is 17F.
Degree days = 1 day ( 65 Tout)
= 1 (65-17)
= 48 degree days
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EGEE 102 12
Heating Degree Days in
a Heating Season Calculate the degree days accumulated
during a 150-day heating season if the
average outside temperature is 17FSolution:
Heating Season Degree days
= 150 days ( 65 Tout)= 150 (65-17)
= 7,200 degree days
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EGEE 102 13
Degree Days for the
Heating SeasonPLACE DEGREE DAYS
Birmingham,
ALABAMA
2,780
Anchorage,
ALASKA
10,780
Barrow, ALASKA 19,994
Tucson, ARIZONA 1,776
Miami, FLORIDA 173
State College ???
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EGEE 102 14
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EGEE 102 15
Class work
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EGEE 102 16
Significance of HDD
Mrs. Young is moving from Anchorage, Alaska(HDD =10,780) to State college, PA (HDD =6,000). Assuming the cost of energy per million
Btu is the same at both places, by whatpercentage her heating costs will change?
Solution
HDD in Anchorage, Alaska = 10,780
HDD in State College PA = 6,000
Difference = 10,780 - 6,000 = 4,780
Saving in fuel costs are %3.44100780,10
780,4
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EGEE 102 17
Home Energy Saver
http://homeenergysaver.lbl.gov/
http://homeenergysaver.lbl.gov/http://homeenergysaver.lbl.gov/7/30/2019 9. Home Heating Basics
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EGEE 102 18
Home Heating Costs in
State College
$890
$133$227
$305
$232 $106 HeatingCooling
Hot water
Appliances
Misc.
Lighting
Energy Effcient House
$327
$89$114
$205
$232
$52
Total $1,891
Average House
Energy EfficientHouse
Total $1,019
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EGEE 102 19
Home Heating Costs
Related to amount of insulation,material that resists the flow of heat
Insulation is rated in terms ofthermal resistance, called R-value,which indicates the resistance toheat flow. The higher the R-value,
the greater the insulatingeffectiveness. The R-value ofthermal insulation depends on thetype of material, its thickness, anddensity.
R-30 better than R-11
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EGEE 102 20
Places to Insulate
Attic is usually theeasiest ad most costeffective place toadd insulation
Floors aboveunheatedbasements shouldbe insulated
Heated basementsshould be insulatedaround thefoundaton
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EGEE 102 21
R-values for Building
Materials
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EGEE 102 22
Thickness of various
materials for R-22
110"
18"
7"6"
CelluloseFiber
Fiberglass Pine wood Commonbrick
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EGEE 102 23
R-Value for a Composite
Wall
1/2" Plasterboard 0.45
3 1/2" Fiberglass 10.90
3/4" Plywood 0.94
1/2" Wood siding 0.81 RTOTAL = 13.10
ft 2 F hrBTU
R-Value of material
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EGEE 102 24
Home Heating Energy
Heat loss dependson
Surface Area(size)
Temperature
Difference
Property of thewall ( R value)
Inside
65F
Outside
30F
Q (Btus)
t (time, h)= A (area) x Temperature Diff (Ti To)
1
R
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EGEE 102 25
Heat Loss
),tanRe( RWallofthecesisThermal
outsideT
insideTxArea
),tanRe( RWallofthecesisThermal
outsideT
insideTxArea Thot
Tcold
Q
t
Heat Loss =Q
t
Id Q/t is in Btu/h
Area in ft2
Tin-Tout in F
Then the thermal resistance is
R-value. The units of R-value are
hrBtu
Fxfto
/
2
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EGEE 102 26
Wall loss rate in BTUs
per hour For a 10 ft by 10 ft room with an 8 ft ceiling,
with all surfaces insulated to R19 as
recommended by the U.S. Department ofEnergy, with inside temperature 68F andoutside temperature 28F:
hrBtu
hBTU
Fxft
FFxft
t
QRateHeatloss /674
/19
286832002
02
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EGEE 102 27
Calculation per Day
Heat loss per day = (674 BTU/hr)(24 hr)= 16,168 BTU
Note that this is just through the wall The loss through the floor and ceiling is
a separate calculation, and usually
involves different R-values
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EGEE 102 28
Calculate loss per
"degree day"
If the conditions of case II prevailed all day, youwould require 40 degree-days of heating, andtherefore require 40 degree-days x 404 BTU/degreeday = 16168 BTU to keep the inside temperatureconstant.
This is the loss per day with a one degreedifference between inside andoutside temperature.
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EGEE 102 29
Heat Loss for Entire
Heating Season. The typical heating requirement for a
Pittsburgh heating season, September
to May, is 5960 degree-days (a long-term average).
Heat loss = Q/t = 404 Btu/degree day x 5960 degree days
= 2.4 MM Btus
The typical number of degree-days of heating
or cooling for a given geographical location
can usually be obtained from the weather service.
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EGEE 102 30
Numerical Example
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EGEE 102 31
Heat loss Calculation
dayhdaysreeAnnualofNumberAR
Qtotal /24deg1
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EGEE 102 32
Problem
A wall is made up of four elements, as follows
wood siding
plywood sheathing 3 in of fibber glass
of sheet rock
How many Btus per hour per sq.ft. will be lostthrough the wall when the outsidetemperature is 50F colder than inside?
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EGEE 102 33
Economics of Adding
Insulation Years to Payback =
C(i) x R(1) x R(2) x E
-------------------------------------C(e) x [R(2) - R(1)] x HDD x 24
C(i) = Cost of insulation in $/square feet
C(e) = Cost of energy, expressed in $/Btu
E = Efficiency of the heating system
R(1) = Initial R-value of section
R(2) = Final R-value of section
R(2) - R(1) = R-value of additional insulation being considered
HDD = Heating degree days/year
24 = Multiplier used to convert heating degree days to heating hours (24hours/day).
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EGEE 102 34
Pay Back Period
Calculation Suppose that you want to know how many years it
will take to recover the cost of installing additionalinsulation in your attic. You are planning to increase
the level of insulation from R-19 (6 inch fiberglassbatts with moisture barrier on the warm side) to R-30by adding R-11 (3.5 inch unfaced fiberglass batts).You have a gas furnace with an AFUE of 0.88. You
also pay $0.70/therm for natural gas. Given C(i) = $0.18/square foot; C(e) = ($0.70/therm)/(100,000
Btu/therm) = $0.000007/Btu; E = 0.88; R(1) = 19; R(2) = 30;R(2) - R(1) = 11; HDD = 7000
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EGEE 102 35
Household Heating Fuel
56%
26.00%
11.00% 10.00%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Natural
Gas
Electricity Fuel Oil Other
Heating Fuel
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EGEE 102 36
Average Heating Value
of Common FuelsFuel Type No. of Btu/Unit (Kilocalories/Unit)
Kerosene (No. 1 Fuel Oil) 135,000/gallon (8,988/liter)
No. 2 Fuel Oil 140,000/gallon (9,320/liter)
Electricity 3,412/kWh (859/kWh)Natural Gas 1,028,000/thousand cubic feet (7,336/cubic meter)
Propane 91,333/gallon (6,081/liter)
Bituminous Coal 23,000,000/ton (6,400,000/tonne)
Anthracite Coal 24,800,000/ton (5,670,000/tonne)
Hardwood (20% moisture)* 24,000,000/cord (1,687,500/cubic meter)Pine (20% moisture)* 18,000,000/cord (1,265,625/cubic meter)
Pellets (for pellet stoves; premium) 16,500,000/ton (4,584,200/tonne)
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EGEE 102 37
Fuel Type - Heating Equipment Efficiency (%)Coal (bituminous)
Central heating, hand-fired 45
Central heating, stoker-fired 60
Water heating, pot stove (50 gal.[227.3 liter]) 14.5
Oil
High efficiency central heating 89
Typical central heating 78
Water heater (50 gal.[2227.3 liter]) 59.5
Gas
High efficiency central heating 92
Typical central heating 82
Room heater, unvented 91
Room heater, vented 78
Water heater (50 gal.[227.3 liter]) 62
ElectricityCentral heating, resistance 97
Central heating, heat pump 200+
Ground source heat pump 300+
Water heaters (50 gal.[227.3 liter]) 97
Wood & Pellets
Franklin stoves 30.0 - 40.0
Stoves with circulating fans 40.0 - 70.0
Catalytic stoves 65.0 - 75.0
Pellet stoves 85.0 - 95.0
Typical Heating Furnace
Efficiencies
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EGEE 102 38
Comparing the Fuel
Costs
EfficiencyunitoffuelMMBtuueHeatingValofFuelperUnitCost
CostEnergy
)/(
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EGEE 102 39
Fuel Costs
Electric resistance heat cost =$0.082 (price per kWh) / [ 0.003413 x 0.97(efficiency)] = $24.77 per million Btu.
Natural gas (in central heating system) cost =$6.60 (per thousand cubic feet) / [ 1.0 x 0.80(efficiency)] = $8.25 per million Btu.
Oil (in central heating system) cost =$0.88 (price per gallon) / [ 0.14 x 0.80 (efficiency)] =
$7.86 per million Btu. Propane (in central heating system) cost =
$0.778 (price per gallon) / [ 0.0913 x 0.80 (efficiency)]= $10.65 per million Btu.
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EGEE 102 40
Heating Systems
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EGEE 102 41
Heating Systems
Some hot watersystems circulate
water throughplastic tubing in thefloor, called radiantfloor heating.
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EGEE 102 42
Electric Heating
Systems1. Resistance heating systems
Converts electric current directly intoheat
1. usually the most expensive2. Inefficient way to heat a building
2. Heat pumpsUse electricity to move heat rather than
to generate it, they can deliver moreenergy to a home than they consume1. Most heat pumps have a COP of 1.5 to 3.5.
2. All air-source heat pumps (those thatexchange heat with outdoor air, as opposed
to bodies of water or the ground) are ratedwith a "heating season performance factor"
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EGEE 102 43
Geothermal Heat Pumps
They use the Earthas a heat sink in the
summer and a heatsource in the winter,and therefore relyon the relative
warmth of the earthfor their heating andcooling production.
Additional reading
http://www.eren.doe.gov/erec/factsheets/geo_heatpumps.html#sidebar
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EGEE 102 44
Benefits of a GHP
System Low Energy Use
Free or Reduced-Cost Hot Water
Year-Round Comfort Low Environmental Impact
Durability
Reduced Vandalism Zone Heating and Cooling
Low Maintenance
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EGEE 102 45
Solar Heating and
Cooling Most American houses receive enough
solar energy on their roof to provide all
their heating needs all year! Active Solar
Passive Solar
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EGEE 102 46
Passive Solar
A passive solar system uses no externalenergy, its key element is good design:
House faces south South facing side has maximum window
area (double or triple glazed)
Roof overhangs to reduce cooling costs Thermal mass inside the house (brick,stones or dark tile)
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EGEE 102 47
Passive Solar
Deciduous trees on the south side tocool the house in summer, let light in in
the winter. Insulating drapes (closed at night and inthe summer)
Greenhouse addition
Indirect gain systems also such as largeconcrete walls to transfer heat inside
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EGEE 102 48
Passive Solar Heating
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EGEE 102 49
Passive Heating
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EGEE 102 50
Dire c t Gain The rmal St o rag e
W a l l
S u n s p a c e
g
Passive CoolingS ha d ing Ve n t ila t io n Earth Cont ac t
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EGEE 102 51
Active Solar Heating
Flat plate collectors are usually placedon the roof or ground in the sunlight.
The sunny side has a glass or plasticcover.
The inside space is a black absorbingmaterial.
Air or water is pumped (hence active)through the space to collect the heat.
Fans or pumps deliver the heat to the
house
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EGEE 102 52
Active Solar
Heating
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EGEE 102 53
Flat Plate Collector
Solar Collectorsheat fluid and theheated fluid heatsthe space eitherdirectly or indirectly
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EGEE 102 54
Efficiency of Furnace
The "combustion efficiency" gives you asnapshot in time of how efficient the heatingsystem is while it is operating continuously
The "annual fuel utilization efficiency" (AFUE)tells you how efficient the system isthroughout the year, taking into account start-up, cool-down, and other operating losses
that occur in real operating conditions. AFUE is a more accurate measure of
efficiency and should be used if possibleto compare heating systems.
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EGEE 102 55
Efficiencies of Home
Heating.
U.S. stock
1975-1976 building practice(NAHB)
LBL standard(medium infiltration)
LBL standard(low inf iltration)
Brownell Saskatoon
Pasqua
Saskatche-wan house
IvanhoeMastin
Leger
BalcombPhelps
1 Btu/ft 2 per degree day
Annualfuelinputfor
spaceheat
(10
6Btu/100
0ft
2)
Btu/ft2perdegreed
ay
Degree days (base 65F)
110
100
90
80
70
60
50
40
30
20
10
00 2000 4000 6000 8000 10,000
9
7
5
3
1
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EGEE 102 56
Tips (Individual) to Save
Energy and Environment Set your thermostat as low as is comfortable in the
winter and as high as is comfortable in the summer.
Clean or replace filters on furnaces once a month or
as needed. Clean warm-air registers, baseboard heaters, and
radiators as needed; make sure they're not blockedby furniture, carpeting, or drapes.
Bleed trapped air from hot-water radiators once ortwice a season; if in doubt about how to perform thistask, call a professional.
Place heat-resistant radiator reflectors betweenexterior walls and the radiators.
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EGEE 102 57
Use kitchen, bath, and other ventilating fans wisely;in just 1 hour, these fans can pull out a houseful ofwarmed or cooled air. Turn fans off as soon as they
have done the job. During the heating season, keep the draperies and
shades on yoursouth-facing windows open duringthe day to allow sunlight to enter your home and
closed at night to reduce the chill you may feel fromcold windows. During the cooling season, keep thewindow coverings closed during the day to preventsolar gain.
http://www.eren.doe.gov/consumerinfo/energy_savers/south_facing.htmlhttp://www.eren.doe.gov/consumerinfo/energy_savers/south_facing.htmlhttp://www.eren.doe.gov/consumerinfo/energy_savers/south_facing.htmlhttp://www.eren.doe.gov/consumerinfo/energy_savers/south_facing.html7/30/2019 9. Home Heating Basics
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Close an unoccupied room that is isolated from therest of the house, such as in a corner, and turn downthe thermostat or turn off the heating for that room or
zone. However, do not turn the heating off if itadversely affects the rest of your system. Forexample, if you heat your house with a heat pump, donot close the ventsclosing the vents could harm theheat pump.
Select energy-efficient equipment when you buy newheating and cooling equipment. Your contractorshould be able to give you energy fact sheets fordifferent types, models, and designs to help youcompare energy usage. Look for high Annual Fuel
http://www.eren.doe.gov/consumerinfo/energy_savers/glossary.htmlhttp://www.eren.doe.gov/consumerinfo/energy_savers/glossary.html