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TRIPLE BOTTOM LINE AND LIFE CYCLE COST ASSESSMENTS
OF SUSTAINABLE RESOURCE MANAGEMENT IN BOSTON, MA
A Thesis Presented
by
Joseph Farah
To
The Department of Civil and Environmental Engineering
in partial fulfillment of the requirements
for the degree of
Masters of Science
in
Civil Engineering
in the field of
Environmental Engineering
Northeastern University
Boston, MA
July 2008
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ABSTRACT
Urban planners today are facing a multitude of problems with the prevailing paradigm of
development. Apart from being hydrologically unbalanced, and operating on a “fast-
conveyance” premise, large cities suffer from high levels of greenhouse gas emissions
and inefficient management of resources. Realizing the need for a different paradigm of
development, this study examines the feasibility of a new urban management approaches
based on the concepts of “Total Hydrologic Balance” and “Sustainability”. Water
conservation and reuse, energy conservation, vegetated roofs, decentralized water
management in semi-autonomous urban clusters, and integrated resource management
were investigated in multiple configurations and assessed for benefits on a “Triple
Bottom Line” basis. Green roofs were studied for water retention, runoff reduction and
building insulation and were found to be effective in reducing runoff from the one-year
storm. However, for larger design storms there’s a need to couple green roofs with other
tools that reduce directly connected impervious areas. For water reclamation, facilities
using biological nutrient removal and yielding a high quality reusable effluent were
proposed inside the urban ecoblocks with their cost estimated from construction curves.
Water and energy conservation were thoroughly dealt with and broken down to direct and
indirect ways to conserve, while proposing low flow fixtures and energy efficient
appliances with no or minimal additional cost. Anaerobic digestion of sludge and heat
extraction from wastewater were also considered as renewable sources of energy. A
“Life-Cycle Cost Analysis” was also used in order to determine the economic viability
and applicability of each proposed alternative. Such analysis revealed that sustainable
management is feasible for different scales of cluster and various land use compositions.
Alternatives centered on water management or green roofs only were not feasible on their
own while comprehensive alternatives using a holistic approach and plans incorporating
energy conservation were the most beneficial. Land use and population density were
analyzed for their effects on the different scenarios. The results suggested that the
payback period was not much affected by those parameters while the net present worth
showed it highest values at 55-70% developed land cover and a population density in the
range of 6000-9000 persons/km2.
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ACKNOWLEDGMENTS
This study could not have been completed were it not for the contribution of various
people. First and foremost, I would to gratefully acknowledge the extensive support and
invaluable advice of my research advisor Professor Vladimir Novotny, who is not only a
leading figure in the fields of water quality and environmental engineering but also an
inspiring supervisor. Gratitude also to Dr. Annalisa Onnis Hayden and Professor Ferdi
Hellweger for their assistance in obtaining necessary data and clearing out ambiguities in
this report. I also greatly appreciate the encouragement of my colleagues and friends at
the Department of Civil and Environmental Engineering, mainly David Bedoya, Indrani
Ghosh, Carla Cherchi, Nehreen Majed, Vanni Bucci and David Doran. Many thanks as
well to my parents Nassim and Layla Farah for always believing in me. And finally I
can’t conclude without thanking God for giving me the strength and the will to finish this
study and move on to greater things.
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TABLE OF CONTENTS Abstract……………………………………………………………………………………. i Acknowledgments………………………………………………………………………… ii Table of Contents…………………………………………………………………………. iii List of Abbreviations……………………………………………………………………... v List of Tables……………………………………………………………………………… vi List of Figures……………………………………………………………………………... vii CHAPTER 1: INTRODUCTION………………………………………………………... 1 1.1 Problem Statement…………………………………………………………………. 1 1.2 Description of this Study…………………………………………………………....10 CHAPTER 2: STUDY AREA……………………………………………………………. 13 CHAPTER 3: WATER AND ENERGY CONSERVATION………………………….. 19 3.1 Water Conservation………………………………………………………………... 19 3.1.1 Toilets and Urinals……………………………………………………………….. 22 3.1.2 Faucets and Taps………………………………………………………………….. 22 3.1.3 Showerheads……………………………………………………………………….. 23 3.1.4 Dishwashers and Washing Machines………………………………………….. 23 3.2 Energy Conservation……………………………………………………………….. 25 3.2.1 Indirect Energy Savings……………………………………………………………26 3.2.2 Direct Energy Savings……………………………………………………………. 27 CHAPTER 4: VEGETATED ROOFS…………………………………………………...31 4.1 Implementation of Green Roofs in this Study……………………………………... 31 4.2 Water Retention by Green Roofs…………………………………………………... 36 4.3 Peak Flow and Runoff Reduction by Green Roofs………………………………… 38 4.4 Direct Energy Savings from Green Roofs…………………………………………. 43 4.5 Cost Considerations………………………………………………………………... 46 CHAPTER 5: WATER SUPPLY, RECLAMATION AND REUSE…………………..48 5.1 Water Supply………………………………………………………………………. 48 5.2 Wastewater Treatment and Reuse…………………………………………………. 50 CHAPTER 6: ALTERNATIVE ENERGY & IRM……………………………………..54 6.1 Anaerobic Digestion and Biogas Production………………………………………. 54 6.2 Heat Extraction…………………………………………………………………….. 57 CHAPTER 7: TBL & LCC ASSESSMENTS…………………………………………...60 7.1 Triple Bottom Line Assessment…………………………………………………….60 7.2 Life Cycle Cost Assessment……………………………………………………….. 65 7.2.1 Vegetated Roofs Only……………………………………………………………... 67 7.2.2 Vegetated Roofs and Energy Conservation……………………………………. 71 7.2.3 Vegetated Roofs, Ecoblocks, IRM, Energy and Water Conservation………. 73
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7.2.4 Vegetated Roofs, Ecoblocks, Water Conservation and Reuse……………......75 7.2.5 No Vegetated Roofs………………………………………………………………...77 7.3 Analysis and Discussion…………………………………………………………… 78 CHAPTER 8: CONCLUSIONS AND FINAL THOUGHTS…………………………...86 APPENDIX A: EXTRACTS FROM IPCC REPORT 2007…………………………….93 APPENDIX B: LAND USE CODE DEFINITIONS……………………………………. 95 APPENDIX C: DATA ON ENERGY REQUIREMENTS FOR WATER CONVEYANCE AND TREATMENT……………………………………………………...96 APPENDIX D: 2005-2007 PRECIPITATION SERIES FOR BOSTON WITH RETAINED DEPTH BY GREEN ROOFS……………………………………………98 REFERENCES……………………………………………………………………………. 107
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LIST OF ABBREVIATIONS BFA Building Footprint Area BNR Biological Nutrient Removal CFL Compact Fluorescent Lights DES Direct Energy Savings GHG Greenhouse Gases GRA Green Roofs Area IES Indirect Energy Savings IRM Integrated Resource Management LCC Life-Cycle Cost LCCA Life-Cycle Cost Assessment NPW Net Present Worth PBP Payback Period TBL Triple Bottom Line WRF Water Reclamation Facility WSC Water Saved by Conservation WWTP Wastewater Treatment Plant YWR Yearly Water Retention
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LIST OF TABLES Table Description Page 2.1 Areas of the Ecoblocks 15 2.2 Population Estimates of the Ecoblocks 16 2.3 Aggregated Codes for each Land Use Category 17 2.4 Land Use Composition of the Ecoblocks 18 3.1 Feasible Water Savings in Residential Households 24 3.2 Feasible Water Savings in Commercial Buildings 24 3.3 Water Saved by Conservation 25 3.4 Energy Requirement for Water-Related Works 26 3.5 Indirect Energy Savings 27 3.6 Direct Energy Saving for Water Conserving Fixtures and Machines 28 3.7 Equivalent Wattage for CFLs for the Same Light Output 29 3.8 Energy Savings Provided by CFLs 30 4.1 BFA and GRA of Ecoblocks 36 4.2 Water Retention Computations 37 4.3 Yearly Water Retention by Green Roofs along with IES 38 4.4 Curve Numbers with Traditional and Green Roofs 39 4.5 Peak Flow Differences between Traditional and Green Roofs 40 4.6 Runoff Differences between Traditional and Green Roofs 41 4.7 Computation of Average ΔT 44 4.8 Yearly Energy Savings Provided by Green Roofs 45 4.9 Total Direct Energy Savings in Ecoblocks 46 4.10 Cost of Green Roofs 47 5.1 Typical Distribution of Residential Water Use 48 5.2 Typical Flow Rates for Commercial and Institutional Buildings 49 5.3 Water Supply Flow Rate 50 5.4 Effluent Quality Provided by BNR 51 5.5 Capital Costs of Water Reclamation Facilities and Yearly 53 6.1 Energy from Anaerobic Digestion of Sludge 57 6.2 Heat Extracted from Sewage 59 7.1 Environmental Benefits 61 7.2 Social Benefits 62 7.3 Economic Benefits 64 7.4 Economic Analysis with Green Roofs Only 68 7.5 Sensitivity Analysis with Green Roofs Only Scenario 70 7.6 Economic Analysis for an Energy-Centric Scenario 72 7.7 Economic Analysis for a Comprehensive Scenario 74 7.8 Economic Analysis for a Water-Centric Scenario 76 7.9 Economic Analysis with No Green Roofs 77
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LIST OF FIGURES Figure Description Page 1.1 US Anthropogenic Greenhouse Gas Emissions 5 1.2 Traditional Water Management in Cities 8 1.3 Proposed Water Management Approach 9 1.4 Benefits to be Quantified using a TBL Assessment 11 2.1 Ecoblock 1 13 2.2 Base Ecoblocks in the Study 14 2.3 Land Use in South Boston 19 4.1 Green Roof Tested at the University of Virginia 33 4.2 Building Footprints with a Zoom on Ecoblock 1 35 4.3 Retention Percentages for Different Categories of Rainfall 37 4.4 %Reduction in Runoff versus the Rooftop Cover 42 5.1 Construction Cost Curve for BNR Water Reclamation Facilities 52 6.1 Integrated Resource Management in BC 55 6.2 Stages of Anaerobic Digestion 56 6.3 Thermodynamic Cycle of Heat Extraction 58 7.1 Incremental Cash Flow Diagram 66 7.2 NPW of the Five Scenarios in the Ecobloks 80 7.3 Payback Period of the Three Feasible Scenarios in the Ecoblocks 80 7.4 NPW versus % Developed 82 7.5 PBP versus % Developed 82 7.6 NPW versus Population Density 83 7.7 PBP versus Population Density 83
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CHAPTER 1
INTRODUCTION
1.1- Problem Statement Most of today’s cities are marred by the corollaries of a flawed pattern of growth that
inflicted upon environmental, social and economic health, hydrology, and water
resources. Based on recommendations from the Wingspread workshop (Racine,
Wisconsin 2006), Novotny and Brown (2007) emphasized the need to adopt a new model
for urban development called the “Fifth Paradigm of Urbanization”. The way in which
man has approached his relationship with his natural environment and water resources
has evolved in five paradigms. At first man enslaved nature and dumped his waste in
unpaved streets waiting for them to be washed off by rain and snowmelt. The people of
the first A.D. centuries used streams for irrigation and transportation and groundwater for
potable water supplies.
It took a few centuries before the engineered practices of storage and conveyance became
widespread, as city populations and ensuing water demands grew. Combined sewers that
emerged in the 18th century collected wastewater and polluted runoff and quickly
conveyed them to streams and lakes, effects that have carried over to the present day. As
man continued to stress the available water bodies and relay his problems to nature, he
created a myriad of problems. Outbreak of pandemics and diseases from the very body
that he uses as an outfall for waste and an intake of water have compelled man to seek a
different model. By the beginning of the 20th century, control of point sources of
pollution was being exerted through a massive practice of building wastewater treatment
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plants. That, however, did not address the issue of polluted runoff. With the increase in
impervious surfaces and the quest for more agricultural yields, urbanization and nonpoint
source pollution prevented any major improvements in the quality of water. Therefore the
need for an approach which deals with diffuse pollution developed and resulted in the
very recent ongoing “end-of-pipe control” or fourth paradigm. A major milestone in this
paradigm was the Clean Water Act of 1972 which emphasized the need to restore the
integrity of waterbodies and protect them against urban and agricultural runoff. That
spurred an intense application of Total Maximum Daily Load (TMDL) and Use
Attainability Analysis (UAA) studies. Undeniably, the current paradigm had some
success in abating waterborne diseases and helped many rivers regain their vitality.
Nonetheless, it failed in preventing the detrimental effects resulting from urbanization
and long distance water transfer.
Today’s urban hubs are hydrologically unbalanced. Impervious surfaces dominating the
landscape of cities have invariably altered the predevelopment hydrologic behavior.
Naturally, rainfall hits the surface or is intercepted by vegetation. It ponds into
depressions and a large portion (~30-40 %) is returned to the atmosphere via evaporation
and transpiration. The remaining portion runs off into streams and rivers or infiltrates into
the ground thereby recharging groundwater formations, which ultimately feed the
baseflow of rivers providing for their perenniality. In contrast, a typical city with its
impermeable streets, curbs and parking lots modifies this cycle by reducing evapo-
transpiration and infiltration on one hand and increasing surface runoff on the other. This
increase in surface runoff is exacerbated by the fact that the existing drainage systems
operate on a “fast-conveyance” premise. In other words, today’s characteristic “inlet-
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sewer- catch basin” or “curb and gutter” drainage system is designed to quickly drain the
runoff from streets and lots and convey it to rivers or wastewater treatment plants
(WWTPs). Therefore peak flows from storms increase by a factor from 4 to 10 in an
urban setting (Novotny, 2003). The direct outcome manifested in increased recurrence of
urban flooding which in the future may be worsened by global climate changes, and the
increased frequency of storm surges. Water which should infiltrate to aquifers and
recharge rivers at its own pace is now being collected and quickly transferred out.
Consequently, urban streams have either lost or suffered a major blow in their baseflow
supply and some have turned from perennial to ephemeral. Several are even termed
“effluent dominated” or “effluent dependent” streams in that the major flow they receive
is the discharge from WWTPs or that the discharge is of relatively good quality that can
support aquatic life. For example, the Los Angeles River is now an ephemeral urban and
the Stony Brook in Boston is currently effluent-dominated. The drop in the groundwater
table due to the lack of infiltration may also cause subsidence of the soil bed and
endanger building foundations. This effect is most observed in the city of Boston,
especially the Back Bay area which was developed by filling into the waters of the Back
Bay and piling timber columns into the fill to serve as building foundations. A drop in the
groundwater table would cause the piles to rot, and that prompted the city of Boston to
use large volumes of fresh water to replenish the groundwater.
Moreover, another problem which has taken its toll on water resources is the long
distance transfer of water and sewage. Because of economy of scale and cost-
effectiveness, high capacity treatment plants were built to service large areas. As such
large pipe networks were needed and water / wastewater was being transferred for long
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distances. This practice has led to flow-deprived source areas and effluent dominated
waters receiving the discharge from the large WWTP. For instance, the Deer Island
WWTP in Boston is the second largest treatment plant in the United States with a
network radius of 30 miles. Such large networks suffer from inflow of rainwater into the
system which can massively increase the volume of water being treated and add
unnecessary costs to the operator. Kate Bowditch (2007), project director at the Charles
River Watershed Association, Boston, noted that the amount of sewage being treated at
the Dear Island WWTP is nearly twice the amount that enters the system due to inflow
into the sewers and illicit stormwater discharges.
The impaired state of the urban environment, however, far transcends the dilemma of
improper water management to the realm of the atmosphere and greenhouse gas (GHG)
emissions. Perry McCarty (2008) singled out high CO2 levels as a major driver for
environmental policy makers in the near future and proposed radical changes in all
aspects of urban water, wastewater and energy management. The International Panel on
Climate Change (IPCC, 2007) assessed the changes in CO2 levels, sea levels, temperature
and snow cover over time. The panel noted that excessive fossil fuel usage and land use
changes were the major cause of elevated CO2 concentrations while agriculture was the
cause of increasing methane (CH4) and nitrous oxide (N2O) concentrations.
Concentrations of those three GHGs now “far exceed pre-industrial values determined
from ice cores spanning many thousands of years”. For instance, the atmospheric
concentration of CO2 in 2005 was measured to be 379 ppm increasing from the
preindustrial value of 280 ppm and exceeding any value in the preceding 650,000 years
(IPCC, 2007).
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Such high GHG concentrations have been correlated with increased radiative forcing,
global air and ocean temperature, widespread reduction of the snow and ice cover and
rising global mean sea levels. Appendix A includes figures and graphs extracted from the
2007 IPCC report showing the aforesaid dramatic changes. IPCC (2007) also asserted
that “most of the observed increase in globally averaged temperatures since the mid-20th
century is very likely due to the observed increase in anthropogenic greenhouse gas
concentrations”, thus putting human activity at the forefront of the problem. Narrowing
down even further reveals that electricity is the major source of anthropogenic CO2
emissions. According to EPA (2007), electricity accounts for 33% of the carbon footprint
followed by transportation at 28% and sources such as wastewater treatment at 3%
(Figure 1.1).
Figure 1.1: US Anthropogenic Greenhouse Gas Emissions
(Source: US EPA Inventory of Greenhouse Gas Emissions and Sink 1990-2005, Feb. 2007)
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The aforementioned drawbacks of current water/wastewater management practices,
coupled with the effects of population growth and global warming, could be solved by a
more sustainable paradigm, the fifth paradigm. This paradigm is still in the conceptual
phase and it’s yet to be adopted as a widespread right model of development [this study’s
greater aim is to contribute to the formulation of this paradigm]. The fifth paradigm can
be called “the paradigm of sustainability”. Sustainable development should “meet the
needs of the present without compromising the ability of future generations to meet their
needs” (Bruntland et al., 1987). Ensuring environmental sustainability is also among the
United Nations development goals for the millennium.
Novotny and Brown (2007) highlighted that sustainability can be achieved through a
holistic approach in water management, an approach concerned with optimizing the
whole rather than focusing on a specific component (drinking water, sewage, stormwater,
heat). This holistic approach can be materialized through the concept of “Total
Hydrologic Balance” whereby the reuse and recycling of water is maximized and the
amount of water leaving the system (loop) is minimized. In an exhaustive manner,
sustainability can be attained by:
- Implementing the concepts of smart green development: rain gardens, bioswales,
eco-roofs, ponds, underground storage tanks and pervious pavement to enhance
storage and infiltration within the watershed, recharge aquifers and minimize
subsidence. Such practices will reduce peaks flows and allow for storage of water
on site, which may be used for flow-augmentation in rivers.
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- Reusing treated effluent for landscape irrigation and flushing toilets. Some
effluents are even of a quality comparable to drinking water and their treatment
facility is called a Water Reclamation Facility (WRF).
- Reduction of imperviousness and the restoration of green corridors planted with
coniferous trees that retain water. This will help mimic the natural hydrology of a
predeveloped natural system by increasing evapotranspiration and infiltration, and
provide habitat for different species. Green corridors also improve the air quality
and reduce noise pollution.
- Decentralizing wastewater treatment and clustering the city into smaller semi-
autonomous developments which may be termed “urban clusters” or “Ecoblocks”.
An urban cluster is a set of buildings and developments with a population in the
order of thousands. The cluster could be delineated by major streets or major
landscape features or it could be one large building. However, an urban cluster
has to be a hydrologically independent entity where water management in-situ is
maximized.
- Water and energy conservation practices at the building level using efficient home
appliance and equipment.
Ultimately, on a wider scale a green and sustainable approach should also incorporate:
- Reduction of energy consumption by building a robust system of public
transportation, electric buses and nonpolluting biofuels. Biofuels may be
produced from wastewater biosolids. Stockholm, Sweeden for example is
currently using biogas to power its bus network, gradually phasing out diesel-
powered buses. “Fortum Energi”, a Stockholm energy company also uses heat
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pumps to extract heat from sewage and provide hot water to about 80,000
apartments. Making a resource out of waste, also called Integrated Resource
Management (IRM) has been recommended in the Capital Regional District
(CRD) of Victoria, BC (Aquatex, 2008).
- Remediating urban brownfields and using them as green space recreation.
- Restoring the baseflow in impaired urban streams. Some urban streams have been
buried in culverts under roads and sustainability suggests that they be daylighted.
Daylighting first order streams which became ephemeral, along with infiltration
enhancing pervious pavements and rain gardens, will restore their baseflow and
aquatic life. It will also facilitate the restoration of second and higher order
streams and make for an interconnected system.
Figures 1.2 and 1.3 below show the difference from a water management perspective
between today’s highly urbanized cities and proposed ecoblocks.
Figure 1.2: Traditional Water Management in Cities
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Figure 1.3: Proposed Water Management Approach (Novotny, 2007)
The proposed approach in figure 1.3 - a rationale in the fifth paradigm - graphically
embodies the components of green sustainable hydrology and water management
outlined above, on both the cluster scale and the city scale. Not shown in the two figures
above though, are elements pertaining to reduction of GHG emissions. However,
reduction of water use and wastewater generation is in turn conducive to a solid reduction
in energy. As it will be shown in later sections, it takes great amounts of energy to treat,
supply and convey water. Wilson (2008) proposed that energy and electricity be saved
based on water management strategy since water and energy constitute a nexus, and as
such a “Total Hydrologic Balance” implicitly includes an energy balance component.
Looking at the bigger picture, a “Total Hydrologic Balance” is an offshoot from the more
general concept of sustainability, which has no definite standards at the moment (Wilson,
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2008). Some standards such as LEED establish some water and energy efficient measures
but they falter at the prospect of measuring the holistic sustainability of a development.
Therefore, Novotny (2007) proposed that sustainability be evaluated within the context of
a “Triple Bottom Line” (TBL) Assessment. This assessment uses “society” and the
“environment” on top of the “economics” to evaluate the benefits of a development since
thinking only in terms of one bottom line, money, has had severe impacts. This means
that a development is sustainable in as much as it brings about environmental/ecological
protection and enhancement measures, enhances the quality of social life, and generates
revenues and savings over its life-cycle.
1.2- Description of this study
This research study will assess based on a TBL approach, the benefits and feasibility of
sustainable management in the city of Boston, a city riddled by the impacts of urban
development where first order streams such as the Stony Brook have been lost,
groundwater levels have been sinking, threatening the integrity of foundations in the
Back Bay area, and where water conservation and reuse is by no means widespread. This
study will investigate optimization of water and energy management at the building level
and at the scale of urban clusters. Proposed changes will have minimum impact on the
outside layout of the city. The reasoning behind this as termed by Speers (2007) is
“successive limited comparison”, which describes that policy makers usually consider
policies which differ from the ones in effect by a relatively small degree, thereby
reducing the number of alternatives to be considered. The city of Boston will be clustered
into ecoblocks different in size with each having its own water reclamation facility
(WRF). These facilities would use Biological Nutrient Removal (BNR) to treat the
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influent wastewater and produce a high quality effluent suitable for reuse such as toilet
flushing, irrigation and streamflow augmentation. The costs of the WRF will be
calculated from construction curves provided by Carollo Engineers, a leading US
company in the construction and operation of wastewater treatment plants. Green roofs
will also be used on buildings inside ecoblocks with an assumption that they are
applicable on 70% of the roof area in the city of Boston. The green roof for this study is
an American Hydrotech vegetated roof with a lightweight roof garden mix provided by
ItSaul Natural LLC (subject of a modeling study conducted at the University of Georgia,
Athens, Georgia). The viability of using heat extraction from wastewater will also be
discussed in largely commercial areas.
Figure 1.4 shows the benefits that will be quantified for each ecoblock based on a TBL
assessment. Certainly sustainable development carries more benefits but the ones below
pertain only to the proposed water/energy conservation policies and elements in this
research study.
Figure 1.4: Benefits to be Quantified using a TBL Assessment
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Savings from energy/water conservation will be tallied on a yearly basis and then a
comprehensive life-cycle cost assessment (LCCA) will be performed for each ecoblock
using the computed initial costs, yearly benefits and yearly expenses. The net present
worth (NPW) will be calculated along with the payback period (PBP) provided that the
alternative proves to be feasible.
Subsequently the objectives of this study are the following:
- Investigate whether sustainable resource management is economically feasible
and if optimization of water and energy consumption at the parcel or household
level would generate enough benefits to recover the investment in the WRF
and/or be able to produce appreciable environmental and social impacts.
- Study the effect of the characteristics of the ecoblock (land use, size, population)
– if any – on the calculated benefits.
- Analyze the results of using vegetated roofs within the framework of a stormwater
management policy on a watershed scale.
- Compare different management alternatives and determine the suitability of each.
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CHAPTER 2
STUDY AREA
The imaginary urban clusters or ecoblocks in this study are located in the southern part of
the city of Boston and as shown in figure 2.2, bound by the mouth of the Charles River
and the Boston inner harbor. The ecoblocks were created by obtaining the GIS shapefiles
of the EOT roads and building footprints from MassGIS1, the commonwealth’s office of
geographic and environmental information within the Massachusetts Executive office of
Environmental Affairs. These GIS data layers, as well as all others in this study use a
Lambert Conformal Projection and a NAD83 Stateplane MA Mainland Coordinate
system. Using ArcMap in ArcView 9.1, clustering of buildings was performed using
major roads as the boundary lines between ecoblocks.
Figure 2.1: Ecoblock 1 (Source: Google Maps)
1 Mass.gov/mgis
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For example, ecoblock 1 is defined by Huntington Avenue (MA Route 9), Massachusetts
Avenue, Tremont Street and Ruggles Street. This ecoblock is basically Northeastern
University with a bit of its Roxbury surrounding. All base ecoblocks (1 to 11) are shown
below in figure 2.2.
1 1
1 0
98
7
6
5
4
3
2
±
0 1,800 3,600900 Meters
South Boston Base Ecoblocks
Projection: Lambert Conformal ConicCoordinate System: NAD 1983 Stateplane MA Mainland
Figure 2.2: Base Ecoblocks in the Study
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The study, however, included more imaginary ecoblocks formed by incrementally adding
adjacent base ecoblocks. The additional number would serve at the very least for
validation purposes and observing the effects as the size of the urban cluster increases.
That being said, ecoblocks 12 to 21 are the sum of the following:
E12 = E1 + E2 E13 = E1 + E2 + E3 E14 = E1 + E2 + E3 + E5 E15 = E1 + E2 + E3 + E5 + E6 E16 = E1 + E2 + E3 + E5 + E6 + E4 E17 = E1 + E2 + E3 + E5 + E6 + E4 + E7 E18 = E1 + E2 + E3 + E5 + E6 + E4 + E7 + E8 E19 = E1 + E2 + E3 + E5 + E6 + E4 + E7 + E8 + E9 E20 = E1 + E2 + E3 + E5 + E6 + E4 + E7 + E8 + E9 + E10 E21 = E1 + E2 + E3 + E5 + E6 + E4 + E7 + E8 + E9 + E10 + E11
Using the “CalculateArea” tool in ArcMap, the areas of the ecoblocks were obtained. As
shown in table 2.1, the areas nearly half a square kilometer to near 19 km2.
Table 2.1: Areas of the Ecoblocks Ecoblock Area (km2)
1 0.506 2 0.464 3 0.668 4 0.689 5 0.690 6 1.539 7 2.310 8 2.135 9 4.300 10 4.299 11 1.141 12 0.970 13 1.638 14 2.328 15 3.867 16 4.556 17 6.867 18 9.002 19 13.302 20 17.601 21 18.742
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The population count for each ecoblock is as well an important defining characteristic,
and a parameter at the center of the computations to follow regarding water supply. In
order to obtain an estimate the census bureau data on MassGIS was used. Shapefiles of
census tracts based on the 2000 census data were downloaded. The shapefiles had
population attributes but a population density attribute was added and computed for all
tracts prior to clipping them to the boundary of each ecoblock. Since attributes that are
not maintained by ArcMap are retained as constant with any manipulation of the data
layer, retaining the population density and not the population is the accurate way if the
layer is to be clipped or joined. Then, the census tracts were clipped using each cluster
and the population of the ecoblock was calculated as the summation of the area of each
interior census tract multiplied by its population density.
Table 2.2: Population Estimates of the Ecoblocks Ecoblock Population Population Density
(persons/km2) 1 4,280 8,460 2 3,340 7,180 3 4,970 7,400 4 13,530 19,630 5 6,040 8,760 6 5,910 3,840 7 23,350 10,110 8 20,030 9,380 9 4,840 1,130 10 31,320 7,290 11 2,000 1,760 12 7,620 7,850 13 12,580 7,680 14 18,630 8,000 15 24,540 6,350 16 38,070 8,360 17 61,420 8,940 18 81,450 9,050 19 86,290 6,490 20 117,600 6,680 21 119,610 6,380
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The population estimates are shown above in table 2.2 along with the overall population
densities for each ecoblock. At this point, it can be figured out from tables 2.1 and 2.2
that the clusters range in size from small community-like clusters to large urban hubs.
Another important consideration that should be discussed at this point is the land use in
each ecoblock which - as it will show later - will also affect water conservation. The 1999
land use dataset on MassGIS was as such downloaded and used to determine the land use
breakdown for the ecoblocks. A description of the land use code definitions is provided
in appendix B. For the interest of this study, residential, commercial, industrial, open
urban and transportation uses will be aggregated and tabulated. Table 2.3 shows the
codes used for the land uses of interest.
Table 2:3: Aggregated Codes for each Land Use Category
Land Use Category Aggregated Codes* Residential 10, 11, 12, 13 Commercial 15
Industrial 16 Transportation 18 Open Urban 3, 4, 7, 17
*Description of all codes is provided in Appendix B
Downloading the land use data layer from MassGIS and using the “Tabulate Areas”
functionality in ArcToolbox, with the tabulation parameter as the land use code, yields
measured surface areas for each land use code from which the percent for each category
can be calculated in each ecoblock. This procedure applies to the base ecoblocks while
for the others the percentages were calculated by weighted averages of their components.
Table 2.4 summarizes the results of the land use categorization and reveals that land use
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is somewhat variable between ecoblocks. Residential, commercial and open urban classes
are the most predominant as it would be expected for typical urban areas.
Table 2.4: Land Use Composition of the Ecoblocks
Ecoblock %Residential %Commercial %Industrial %Open Urban
%Transportation
1 11 14 0 53 22 2 36 13 11 30 10 3 40 12 8 25 15 4 37 37 0 26 1 5 43 20 0 32 5 6 4 44 28 7 17 7 36 49 0 12 3 8 41 29 0 19 11 9 0 10 17 40 34 10 13 50 0 17 20 11 6 30 1 3 60 12 23 14 5 42 16 13 30 13 6 35 16 14 34 15 5 33 13 15 22 27 14 23 14 16 24 28 12 24 12 17 28 35 8 20 9 18 31 34 6 19 10 19 21 26 9 27 17 20 19 32 7 24 18 21 18 32 7 22 21
Figure 2.3 is a land use map of the area engulfing the ecoblocks which was used to obtain
the land use breakdown inside each cluster.
This area also suffers from subsidence in the pile foundations under many historic
buildings in the Back Bay area because of the lack of groundwater recharge and the drop
in the groundwater table despite the annual precipitation averaging 45 inches (NOAA,
2008). GHG emissions and below the nationwide average for the United States: 0.466
Tons CO2, 0.02647 Tons CH4 and 0.00616 Tons per MWh of electricity (DOE EIA,
2007).
19
±
0 2,000 4,0001,000 Meters
Projection: Lambert Conformal ConicCoordinate System: NAD 1983 Stateplane MA Mainland
Land Use Catgory
Crop Land
Pasture
Forest
Non-Forested Wetland
Mining
Open Land
Participation Recreation
Spectator Recreation
Water-Based Recreation
Multi-Family Residential
High Density Residential
Medium Density Residential
Low Density Residential
Salt Water Wetland
Commercial
Industrial
Urban Open
Transportation
Waste Disposal
Water
Woody Perennial
Land Use in South Boston
Figure 2.3: Land Use in South Boston
20
CHAPTER 3
WATER AND ENERGY CONSERVATION
The conservation of water, its reuse and source reduction are an integral part of
sustainable water management and an important component of integrated resource
management (Aquatex, 2008). With efficient water management at the building level
being an integral part of this study, this chapter enumerates the water and energy
conserving household practices that, if used in the household within the ecoblocks, would
generate savings in water supply and wastewater treatment as well as reduce the stress on
the regional waterbodies. Based on the New York City census figures, the per capita use
of water in 2003 was 136.6 gallons per day for all uses, down from 141.8 gallons in 2002
and 154.5 gallons in 2001. This decline can be associated with an awareness of the need
to conserve water, even in the Northeast of the US, as well as a way to plug the leaks in
the pipeline system.
3.1- Water Conservation
Conservation can de defined as any action that reduces water use, with the resources used
to generate the savings having a lesser value than the resources saved (DeMonsabert,
1998). The resources saved, in addition to water, can be fuel oil, natural gas and other
energy sources. Wilson (2008) stipulated that savings in water are necessarily tantamount
to savings in energy because of the “water-energy nexus”. For example, it is generally
assumed that wastewater treatment and pumping consumes 2.85 kWh per kgal treated.
Water conservation is achieved through low-flow fixtures and enhancement devices such
as automatic controls. Obviously the applicability of these devices depends on the use of
21
the structure and subsequently land use but their application is mandated by the Energy
Policy Acts of 1992 and 2005. The 1992 act introduced new water efficiency standards
which were aimed at significantly reducing the amount of water consumed by typical
fixtures: water closets, lavatory faucets, kitchen faucets, shower heads and others. Shortly
after it was enacted, a series of incentive programs were launched in multiple cities to
replace heavy usage fixtures with more efficient fixtures compliant with the Energy
Policy Act. In 1994, the New York City residential rebate program replaced 1,635,000
old-style water closets with units using 1.6 gallons per flush while the state of
Massachusetts also followed suit and ensured that only 1.6 gallons per flush toilets are
sold (MWRA, 2006).
However, for a sustainable use of water resources, according to DeMonsabert, water
conservation needs to be taken beyond the provisions of the Energy Policy Act as
technology has taken significant strides since 1992 and efficient water management
became a more persistent need. DeMonsabert (1998) proposed that efficiency be
evaluated on an individual basis for each target structure (commercial building,
residential, industrial, federal building) in a detailed and comprehensive assessment of
what fixtures can be optimized in a model he called the “Watergy” model. Watergy,
which combines water and indirect energy conservation, was used by DeMonsabert in a
study for the federal government to optimize water consumption in federal facilities. The
rationale behind the Watergy model is used this study on a more generalized scale to
optimize the water supply for each ecoblock. Subsequently the following is a listing of
the applicable water conserving fixtures as well as their contribution to savings in water
and energy.
22
3.1.1- Toilets and urinals
Toilets are among the best candidates for cost effective water consumption reduction,
representing about 35% of residential water use and up to 70% of interior water use in an
office building or commercial establishment (Metcalf and Eddy, 2003). Prior to 1994,
most toilets used 3.5, 5.5 or even up to 7 gallons per flush (gpf) but after the Energy
Policy Act, virtually most households were since equipped with 1.6 gpf in compliance
with the code. However, sustainability requires further refinement and suggests that ultra
low-flow water closets with 0.8 gpf be used in new developments. These toilets
according to Chanan at el. (2003) cost nearly the same as their code required
counterparts. With a difference of 0.8 gpf between the code required and the high
efficiency toilets, and using a typical number of 4 flushes/capita/day, savings equaling
3.2 gal/capita/day can be achieved in both residential and commercial buildings.
As for urinals, their use is restricted to commercial and some industrial establishments.
High efficiency waterless urinals are now available. Most of these systems operate
through the use of an oil barrier between urine and the surrounding air space thus
preventing odors from escaping. Waterless urinals would generate savings of 4
gal/male/day or 2 gal/capita/day.
3.1.2- Faucets and taps
Typical non-efficient taps usually use 2.5 gpm (gallons per minute) of flow. There’s
widespread use of automatic faucets incorporating infrared motion sensors and having the
potential to reduce the faucet’s flow by 70%. However, these fixtures would be too costly
for residences and small office buildings and their use is restricted to large structures such
as airports and shopping malls. Since the scope of this study is to research fixtures with a
23
base cost identical or close to the status quo fixtures, these automatic faucets are
excluded. Instead, a more efficient approach proposed by Chanan et el (2003), would be
adjusting the flow rate of taps while maintaining spray pattern through the installation of
flow regulating tap aerators. Such efficient taps would have a flow of 0.7 – 1.8 gpm.
Assuming a reduction to only 1.8 gpm – which happens at a minimal additional cost – 0.7
gpm can be saved relative to 2.5 gpm. Considering a use of 5 minutes per day for each
individual, at least 3.5 gal/capita/day of water savings can be achieved in both residential
and commercial buildings.
3.1.3- Showerheads
While showering may be the largest source of residential water demand, shower demand
is not as high in commercial buildings except for hotels. Typical non-efficient
showerheads have a flow rate of approximately 10 L/min (2.6 gpm) while the Energy
Protection Act requires the use of 2.5 gpm heads. Highly efficient showerheads only use
1.8 gpm (DeMonsabert, 1998) and the resulting savings of 0.7 gpm translate into 10.5
gal/capita/day with daily 15 minute showers per person.
3.1.4- Dishwashers and Washing Machines
After toilets and showerheads, washing machines make up the next largest percentage of
residential water use. Savings in this section will be quoted straight out of the “Watergy”
model where DeMonsabert reported that efficient washing machines yield savings of 4
gal/capita/day (55 gal per load - standard vs 42 gal per load - efficient at 0.2 loads per day
per person) while efficient dishwashers only yield savings of 1 gal/capita/day (14 gallons
per load - standard vs 8.5 gallons per load – efficient at 0.17 loads per person per day).
24
Therefore, from a water conservation perspective, this study will only assume the use of
efficient washing machines.
Putting it all together, tables 3.1 and 3.2 summarize the savings in the sections above for
residential and commercial buildings. The total savings will be applied to the proposed
water supply policy.
Table 3.1: Feasible Water Savings in Residential Households
Fixture/Machine Standard/Code Sustainable/Low-flow
Water Savings (gal/capita/day)
Water Closet 1.6 gpf 0.8 gpf 3.2
Faucets/Taps 2.5 gpm 1.8 gpm 3.5
Showerheads 2.5 gpm 1.8 gpm 10.5
Washing Machines 55 gal per load 42 gal per load 4
Total Water Savings 21.2
Table 3.2: Feasible Water Savings in Commercial Buildings
Fixture/Machine Standard/Code Sustainable/Low-flow
Water Savings (gal/capita/day)
Water Closet 1.6 gpf 0.8 gpf 3.2
Urinals 1 gpf 0 gpf 2
Showerheads 2.5 gpm 1.8 gpm 2.2*
Faucets/Taps 2.5 gpm 1.8 gpm 3.5
Washing Machines 55 gal per load 42 gal per load 1*
Total Water Savings 11.9
* Limited to hotels which are estimated to be 20% of commercial buildings in South Boston
The tables above show that 21.2 and 11.9 gallons/capita/day of fresh water can be saved
in residential and commercial buildings respectively. The more conservative and better
25
rounded figures of 20 and 10 gallons/capita/day will be used in subsequent analysis. A
reduction of 8 gallons/capita/day will also be used for industrial buildings.
The calculation of the yearly water savings for each ecoblock due to water conservation
(WSC) will be done by multiplying the total population by the percents of residential and
commercial/industrial land uses and then by the appropriate feasible water saving
computed above. This is represented by equation 3.1 and the results are tabulated in table
3.3.
WSC = Population ×(%Res×20 + %Com×10 + %Ind×8)×365 (3.1)
Table 3.3: Water Saved by Conservation Ecoblock WSC (m3/yr)
1 21,290 2 43,220 3 67,510 4 207,530 5 88,500 6 60,708 7 390,310 8 307,110 9 15,780 10 328,800 11 11,840 12 67,340 13 135,240 14 223,860 15 278,660 16 450,220 17 826,470 18 1,134,220 19 896,450 20 1,228,290 21 1,216,160
3.2- Energy Conservation
As briefly indicated in 3.1, energy can be saved indirectly by saving water and directly by
energy efficient appliances.
26
3.2.1- Indirect Energy Savings
When water is saved at the building level energy is saved in pumping and distribution,
water treatment, sewerage and wastewater treatment. Also, it has to be noted that the
quantity of water saved at the end user does not equal the water saved from a water
supply perspective due to unaccounted for (UAF) losses such as line leaks, breaks and
inefficient metering. The average water utility in Massachusetts has a 10% UAF factor
(AWWA, 1992). Leakage or UAF do not typically apply to wastewater systems since
wastewater collection is not usually pressurized. On the contrary, the problem is actually
infiltration and inflow into the waste flow. However, the assumption that every volume of
water conserved yields the same volume of wastewater reduction still holds. Appendix C
includes data regarding the energy requirements for water conveyance and treatments
obtained from the American Water Works Association (AWWA)’s Water Industry
Database (WIDB) as well as a presentation by Michael Wilson, CH2M HILL (NEWEA
Annual Conference 2008). Extracted from appendix C, the following numbers in table
3.4 will be used.
Table 3.4: Energy Requirement for Water-Related Works
Activity Energy Requirement (kWh/MG)
Water Supply and treatment 1800
Pumping and Distribution 700
Wastewater Collection and Treatment* 2000
* Treatment up to the Secondary Level
Using the figures above, the indirect energy savings (IES) in kWh per year can be
computed by equation 3.2.
IES = WSC ×(1800/0.9 + 700 + 2000) = 4700 ×WSC (3.2)
27
Using equation 3.2, the indirect energy savings can be computed for the ecoblocks in
study. The results are tabulated in table 3.5.
Table 3.5: Indirect Energy Savings
Ecoblock IES (kWh/yr) 1 26,440 2 53,670 3 83,830 4 257,700 5 109,890 6 75,380 7 484,660 8 381,350 9 19,600 10 408,280 11 14,700 12 83,620 13 167,930 14 277,980 15 346,020 16 559,050 17 1,026,260 18 1,408,400 19 1,113,160 20 1,525,220 21 1,510,160
3.2.2- Direct Energy Savings Direct savings are defined as savings to the end user and the supplier in the form of
reduced energy usage. Direct energy savings (DES) can be achieved by the reduction of
hot water use (already achieved by water conservation), the use of energy-efficient home
appliances and compact florescent lights. There are also significant direct energy savings
from green roofs but that will discussed in the relevant chapter.
Retracting to section 3.1, many water conserving fixtures were examined. Nonetheless,
only faucets, showerheads, dishwashers and washing machines use hot water and as such
28
are capable of generating direct energy savings. These savings depend on the efficiency
of the boiler and are not as important as the other components of DES. For that reason,
the numbers used by DeMonsabert in the “Watergy” model will be also used in this study
(table 3.6).
Table 3.6: Direct Energy Saving for Water Conserving Fixtures and Machines (DeMonsabert, 1998)
Fixture or Machine DES (kWh/capita/day)
Faucets 1
Showerheads 1
Washing Machines and Dishwashers 0.3
Outside the circle of water lies another key factor in sustainable development and
particularly energy conservation: electricity. In 2003, electricity used in housing units
accounted for 22% of the US energy consumption (Hojjati and Battles, 2005). Also
according to the 1997 Residential Energy Consumption Survey, lighting and appliances
used 27% of household electricity and accounted for more than 45% of the energy costs.
Realizing the need to reduce the toll of high electrical consumption, the US EPA, in
conjunction with the Department of Energy launched the Energy Star program which
identifies high efficiency appliances and rates the models that exceed the federal
minimum efficiency standard (by 15-20%). The Energy Star program calculated that at
least 300 kWh of energy (per household) can be saved annually by using appliances
labeled with an Energy Star tag. Much more significant savings can be accrued in
specific cases and households. There are even high performance appliances that yield
great savings in energy over their life cycle but with a relatively large initial cost. For the
scope of this study, the simple savings of 300 kWh per household or 75 kWh per capita
29
(based on an average occupancy of 4 persons per housing unit) will be used. Energy Star
still estimates that, despite fairly widespread use, half of the appliances nationwide are
not rated. As such, it will be assumed that for optimal energy performance, households in
the ecoblocks would conserve 150 kWh per unit.
More direct energy savings however can be achieved through CFLs (Compact
Fluorescent Lamps). Standard pear-shaped incandescent lamps produce a lot of heat,
which prompted the Energy Star program to recommend the use of CFLs to save energy
and money while still providing quality light especially in high use lighting areas such as
kitchens, living rooms and outdoor fixtures. EPA also reassures consumers that CFLs
safely produce steady, quiet and warm light while the problems of poor color and little
noise that plagued the first generations of these lights have been eliminated. They also
come in a variety of shapes and sizes to fit different fixtures. The main advantage though
is that they use far less watts than incandescent lights in order to produce the same light.
As shown in table 3.7, CFLs consume at least 25% of watts used by incandescent lights
but they still produce the same light intensity measured in Lumens. However, even
though CFLs are recommended by Energy Star, only 1.5 out of 43 household in Boston
use any sort of CFL according to a survey conducted at the energy efficiency department
at NSTAR, a major power supplier for Boston residences (2006).
Table 3.7: Equivalent Wattage for CFLs for the Same Light Output (Source: EnergyStar.com)
Incandescent Bulb Compact Fluorescent Light Output (Lumens) 40 W 13 W 490-510 60 W 15 W 870-890 75 W 20 W 1190-1200 100 W 25 W 1680-1705
30
Therefore, considerable savings in energy can be achieved by using CFLs in the
theoretical ecoblocks of this study. Using a typical wattage requirement of 1.5 W/ft2, an
average daily usage of 5 hours, the building footprints area with a minimum of 3 stories,
and a reduction factor of 0.4, the savings by using CFLs were computed. The results are
shown in table 3.8.
Table 3.8: Energy Savings Provided by CFLs Ecoblock Energy Savings (MWh/yr)
1 3866.2 2 2515.3 3 6793.6 4 7062.9 5 3354.4 6 9469.3 7 18350.9 8 17966.3 9 17445.4 10 33211.9 11 5942.7 12 6381.4 13 13175.0 14 20237.9 15 23592.2 16 33061.6 17 51412.4 18 69147.3 19 86592.7 20 119804.6 21 125747.3
31
CHAPTER 4
VEGETATED ROOFS
Green roofs or vegetated roofs use engineered growing media, drought tolerant plants,
and specialized roofing materials installed on existing structures (Peck et al., 1999). This
makes the rooftop capable of absorbing and retaining stormwater rather then rapidly
conveying it into stormwater drainage systems. Therefore, they are a kind of structural
controls designed to treat stormwater and mitigate the effects of increased runoff peak
rate and volume due to urbanization. Variants of vegetated roofs have been used
throughout history, but modern designs were mostly developed in Germany in the 1960s.
As such, green roofs have traditionally been mostly used in Europe (and in Scandinavia
for centuries) but they are becoming increasingly popular in North America. As this study
is not centered on green roofs, the chapter will deal with this topic strictly from a
sustainability perspective.
4.1- Implementation of Green Roofs in this Study
One component of the NPDES permitting process is the requirement to use stormwater
BMPs (Best Management Practices). Most common BMPs such as stormwater ponds,
wetlands, and vegetated swales are used to meet the goals of water quality enhancement
and flood protection but their major drawback is their land requirement. Readily available
undeveloped space is scant in urbanized and metropolitan areas meaning that it would
probably be easier for stormwater management to be implemented within or into the built
environment. Remarkably, according to Carter (2007) rooftops have been overlooked as a
tool for solving urban environmental problems even though they constitute a large
32
fraction of the total impervious surface cover (ISC). Moreover, studying the application
of green roofs within the frame of watershed management is more of a clear-cut relative
to other practices such as rain gardens or pervious pavement because the matrix of their
application (i.e. the concrete roof) can be easily identified and loaded into tools such as
GIS. Virtually all cities in the US have developed GIS layers of their building footprints
and that is greatly propitious for the study of green roofs. On the other hand for instance,
the study of rain gardens or pervious pavements is parcel-specific because of the complex
factors governing their application (e.g. location of catch basins, traffic loads …) and it
would be rather hard to find a tool that helps the study of their application on a watershed
basis.
The main concern for retrofitting green roofs on existing structure is the risk of exceeding
its load bearing capacity. However, this concern will not be touched upon in this study
firstly because it involves the use of an extensive (rather thin) type of vegetated roof
which is not expected to put much strain on the structure and secondly because the life
cycle assessment will be done for imaginary ecoblocks assumed to be developed from
scratch where the use of vegetated roofs has been accounted for.
In this research project, stormwater retention, the mitigation of peak flows and the
thermal insulation effects of green roofs will be quantified. Eventually, the calculation of
the total Direct Energy Savings (DES) will be possible at the end of this chapter. Data in
this study regarding the hydrologic behavior of green roofs rely heavily on research being
conducted at the Institute of Ecology in the University of Georgia, Athens, GA under the
supervision of Dr. Timothy Carter. A 42.64 m2 and about 3-in thick simple to build and
easy to replicate green roof test plot was established on the campus using an American
33
Hydrotech – a supplier for the specialized green roofing materials – extensive roof
garden. Supplied materials included “a WSF40 root protection sheet, an SSM45 moisture
retention mat, a floradrain FD04 synthetic drainage panel, and a Systenfilter SF geotextile
filter sheet”2 (American Hydrotech, 2002). The growing media was a lightweight roof
garden mix provided by ItSaul Natural while the soil mix was a blend of 55% stalite
expanded slate, 30% USGA sand and 15% organic matter. Also, six drought-tolerant
species of plantation were chosen because of their ability to survive heat, temperature
fluctuation, and low moisture and nutrient conditions at the roof surface. A photo of the
test plot at the University of Georgia, as well as a cross section of the researched green
roof adapted in this study, are shown in figure 4.1.
Figure 4.1: Green Roof Tested at the University of Virginia (Carter and Keeler, 2007)
2 quoted from Carter and Keeler (2007)
34
The matrix of application of the above extensive green roof is the rooftops of the
buildings within the ecoblocks which is generally equal to the building footprint area
(BFA). The rooftop is typically the same size as the building’s footprint and is the
structure’s barrier against rainfall and solar radiation. As indicated earlier, it has been
overlooked as a space with the potential to become an environmental amenity rather than
an impervious surface contributing to urban runoff. To the extent that this is possible, the
whole building becomes “economically and functionally more efficient with a more
benign effect on the surrounding landscape” (Carter and Keeler, 2007). Hence, a GIS
layer of the building footprints in the metropolitan Boston area was downloaded from
MassGIS and clipped to the boundaries of the ecoblocks one at a time, in order to obtain
building footprints datasets for each one of them. Figure 4.2 is a map showing the
building footprints in the ecoblocks with a zoom on ecoblock 1 where the building
footprints were filled with a roof garden pattern. It should also be noted that since
clustering was done based on major roads, no footprint is cut or distorted.
Using the functionalities of ArcMap, the total BFA was calculated for each cluster by
summing the individual areas of the footprints inside the ecoblock, a field that is
automatically maintained by ArcMap. For practical purposes, it will be assumed that the
above described green roof will be retrofitted on 70% of the rooftop area (or BFA) to
account for some cases of inadequacy or presence of roof equipments. The green roofs
area (GRA) will as such be the measured BFA multiplied by 0.7. The BFA and GRA for
the ecoblocks are tabulated in table 4.1 and constitute important parameters for the
calculations to follow (water retention, peak flow reduction and energy conservation by
green roofs).
35
1 1
1 0
98
7
6
5
4
3
2
±
0 1,800 3,600900 MetersProjection: Lambert Conformal ConicCoordinate System: NAD 1983 Stateplane MA Mainland
Building Footprints in the Ecoblocks
A Zoom on Ecoblock 1
Figure 4.2: Building Footprints with a Zoom on Ecoblock 1
36
Table 4.1: BFA and GRA of Ecoblocks Ecoblock BFA (m2) GRA (m2)
1 150,308 105,216 2 97,789 68,452 3 264,119 184,883 4 274,590 192,213 5 130,411 91,288 6 368,148 257,704 7 713,443 499,410 8 698,493 488,945 9 678,242 474,769 10 1,291,209 903,846 11 231,038 161,727 12 248,097 173,668 13 512,216 358,551 14 786,806 550,764 15 917,217 642,052 16 1,285,365 899,756 17 1,998,808 1,399,166 18 2,688,301 1,881,811 19 3,366,543 2,356,580 20 4,657,752 3,260,426 21 4,888,790 3,422,153
4.2- Water Retention by Green Roofs
As indicated, the BFA is the matrix for the GRA, the milieu where water retention will
occur during rainfall events. Carter and Rasmussen (2006) established a relationship
between the percent of stormwater retained and the depth of precipitation for the tested
green roof system. This inversely proportional relationship is shown in figure 4.3 where
the percent retained is plotted versus the rainfall depth for an average moisture content in
the green roof. This figure suggests that 88% of the rainfall is retained for storms less
than 1 inch (2.54 cm) while only 48% is retained for storms of about 3 inches (7.62 cm).
These percents will be used in order to calculate the potential yearly water retention in
the ecoblocks with the use of green roofs. In order to do that, a three-year precipitation
37
series for Boston was obtained from the National Oceanic and Atmospheric
Administration (NOAA)’s database. The precipitation, spanning from 01/01/2005 to
12/31/2007, is provided in appendix D along with the amount of rainfall retained from
each daily amount of precipitation. Care was taken in observing and analyzing the rainfall
data so that these computations were applied to intermittent moderate storms that
maintain a low to average moisture content in the vegetated roof.
Figure 4.3: Retention Percentages for Different Categories of Rainfall (Carter and Rasmussen, 2006)
The results of the computation provided in appendix D are summarized in table 4.2. The
average retention is 75% of the yearly rainfall or 83.45 cm will be used to calculate the
volume of annual retention.
Table 4.2: Water Retention Computations
Year 2005 2006 2007
Total Rainfall (cm) 108.79 129.59 96.24 Depth Retained by Green roofs (cm) 84.45 94.64 71.27
% Retention 78 73 74
38
The volume (in m3) of water retained yearly by the green roofs (YWR) will be calculated
for each ecoblock by multiplying the GRA inside the ecoblock by the average retention
depth for Boston per year. This retained water, which could otherwise end up being
discharged into combined sewers, in turn brings about indirect savings in energy similar
to water conservation. The amounts are tabulated below in table 4.3.
Table 4.3: Yearly Water Retention by Green Roofs
along with Indirect Energy Savings Ecoblock YWR (m3/yr) IESGR (kWh/year)*
1 87,800 46,390 2 57,120 30,180 3 154,290 81,530 4 160,400 84,760 5 76,180 40,250 6 215,050 113,630 7 416,760 220,220 8 408,030 215,600 9 396,200 209,350 10 754,260 398,550 11 134,960 71,310 12 144,930 76,580 13 299,210 158,100 14 459,610 242,860 15 535,790 283,110 16 750,850 396,750 17 1,167,600 616,960 18 1,570,370 829,780 19 1,966,570 1,039,104 20 2,720,830 1,437,690 21 2,855,790 1,509,000
* based on 2000 kWh/MG for Wastewater Collection and Treatment (Wilson, 2008)
4.3- Peak Flow and Runoff Reduction by Green Roofs
The reduction in peak flows and urban runoff will be computed using the NRCS-CN
(National Resources Conservation Service – Curve Number) model which is widely used
amongst engineers and watershed analysts. Residential, commercial and industrial areas
39
were assigned CNs of 92, 92 and 88 respectively while impervious surfaces such as
transportation related surfaces were assigned a CN of 98 and a CN of 67 was used for
open urban spaces (NRCS, 1986). Composite CNs representing the status-quo (traditional
roofs) were determined for the ecoblocks by calculating averages weighted by the land
use classifications. Carter and Rasmussen (2006) experimentally derived a CN of 86 for
green roofs by regressing storage and runoff. This CN was assigned to 70% of the
residential and commercial areas in the ecoblocks and new composite CNs representing
the scenario with green roofs were computed. The CNs for the ecoblocks with traditional
roofs (TR) and green roofs (GR) are shown in table 4.4. The calculations in this section
were performed for the base ecoblocks along with ecoblock 21 (all ecoblocks).
Table 4.4: Curve Numbers with Traditional and Green Roofs
Ecoblock CNTR CNGR 1 80.6 79.4 2 84.3 82.2 3 86.3 84.1 4 85.3 82 5 84 81.6 6 89.1 86.4 7 88.7 84.7 8 87.4 84.4 9 83.8 82.9 10 88.7 85.3 11 94.3 92.3 21 86.8 84.2
Runoff modeling was performed using Hydraflow-Hydrographs 2007 using the
composite CNs above for the two scenarios of traditional and green roofs. The chosen
storms for the analysis were the 1, 10 and 50-year storms to understand how the results
vary with the storm frequency. Using normalized storm duration-frequency-intensity
curves (Novotny et al., 1989), the 1, 10 and 50-year 6-hour precipitation values for
40
Boston were calculated as 36 mm (1.42 in), 72 mm (2.83 in) and 156 mm (6.14 in)
respectively. In the Hydraflow model, an average basin slope of 0.4% and a hydraulic
length of 100ft were used as typical values for urban areas. The peak flows, runoff depths
as well as the reductions with the use of green roofs are shown below in tables 4.5 and
4.6.
Table 4.5: Peak Flow Differences in the Ecoblocks between Traditional and Green Roofs
P 1 = 1.42” (36 mm) P 10 = 2.83” (72 mm) P50 = 6.14” (156 mm)
Ecoblock Qp TR Qp GR % Red Qp TR Qp GR % Red Qp TR Qp GR % Red
1 0.655 0.544 17 3.52 3.27 7.1 12.46 12 3.7 2 0.973 0.775 20 4 3.6 10 12.52 12 4.3 3 1.1 0.825 25 4.8 4.3 9.5 15.1 14.5 4 4 1.6 1.08 32.5 6.22 5.2 16.4 19 17.58 7.5 5 1.38 1.03 35 5.8 5.08 12.4 18.43 17.42 5.5 6 5.15 3.93 23.7 16.21 14.27 12 43.7 41.63 4.7 7 7.44 5 32.8 23.9 20.18 15.6 65.17 62.75 3.7 8 6.05 4.47 26 20.78 18.35 11.7 58.86 57.6 2.2 9 8.4 7.54 10.2 35.75 34 5 114.42 112 2.1 10 13.84 10 27.7 44.47 38.8 12.8 121.25 118.37 2.4 11 6.07 5.14 15.3 14.76 13.74 6.9 34.77 34 2.3 21 50 38.4 23.2 177.2 159.3 10.1 511 503.2 1.5
The results in the tables 4.5 and 4.6 give clear indications on the effect of widespread
roof greening on the hydrology of urban subwatersheds. This effect is dependent on two
factors: the Rooftop Cover (RTC) and the design storm. The RTC normalized by the area
of the ecoblock were the highest for ecoblocks 3, 4 and 14 (0.4, 0.4 and 0.34) and lowest
for ecoblocks 2, 5 and 9 (0.21, 0.19 and 0.16). The variety of RTCs and land uses in this
study help evaluate the efficiency of green roofs from a stormwater management
perspective under different scenarios.
41
Table 4.6: Runoff Differences in the Ecoblocks between Traditional and Green Roofs P 1 = 1.42” (36 mm) P 10 = 2.83” (72 mm) P50 = 6.14” (156 mm)
Ecoblock R TR R GR % Red R TR R GR % Red R TR R GR % Red
1 6.66 5.87 11.8 29.55 27.74 6.1 100.88 97.73 3.1 2 9.54 7.81 18.1 35.61 32.08 10.0 110.78 105.12 5.1 3 11.43 9.36 18.1 39.21 35.26 10.1 116.25 110.24 5.2 4 10.45 7.66 26.7 37.38 31.75 15.0 113.50 104.59 8.0 5 9.28 7.36 20.6 35.09 31.11 11.3 109.96 103.52 5.9 6 14.58 11.53 21.0 44.68 39.39 11.8 124.05 116.53 6.1 7 14.09 9.90 30.0 43.87 36.31 17.2 122.93 111.87 9.0 8 12.59 9.63 23.6 41.30 35.78 13.4 119.29 111.05 7.0 9 9.10 8.36 8.2 34.74 33.23 4.4 109.42 107.00 2.2 10 14.09 10.45 25.8 43.87 37.38 14.8 122.93 113.50 7.7 11 22.46 19.05 15.2 56.37 51.62 8.4 138.98 133.17 4.2 21 11.95 9.45 21.0 40.15 35.43 11.7 117.63 110.51 6.1
Reductions in surface runoff of 30% for the one-year storm, 17% for the ten-year storm
and 9% for the fifty-year storm were calculated in table 4.6 for ecoblock 7, a highly
urbanized ecoblock at the heart of South Boston. At the parcel level, the reduction in
runoff will tend to be much higher while it gets masked when ecoblocks are aggregated
into larger ones and properties become more uniform, as shown in table 4.6 where the
reductions level off and even decrease as the scale edges to a watershed level. When
green roofing is considered as a tool to minimize the impact of stormwater, areas zoned
commercial, industrial, institutional centers or sizeable residences which are known to
contain large flat-roofed buildings should be targeted. Ecoblock 7, which bears the best
results, has the highest commercial land use percentage (49%).
The second major factor governing the findings in this section is the design storm. As the
precipitation increases, runoff volumes increase and associated runoff reductions from
vegetated roofs are lessened. The drop in stormwater retention is the outcome of the roof
42
reaching its maximum saturation content and then quickly releasing rainfall from large
storms similar to a conventional concrete roof. Therefore, regardless of the scale of green
roof installation, the change in the hydrology of across a watershed will be minimal with
storm events larger than the one or two-year storm. Thus, it is important to consider the
rainfall distribution pattern for the specific watershed. Frequent storms of light rain will
be better retained by the vegetated roof than sporadic heavy downpours. In Boston, MA,
a large number of storms follow a pattern suitable for green roofing, hence the 75%
retention computed in the previous section. Figure 4.4 show the runoff reduction
percentage versus the RTC normalized by the total area for various design storms
(highest point for each storm represents ecoblock 7).
y = 12.262Ln(x) + 36.377R2 = 0.404
y = 7.2147Ln(x) + 20.815R2 = 0.387
y = 3.9382Ln(x) + 11.057R2 = 0.408
0
5
10
15
20
25
30
35
0.00 0.10 0.20 0.30 0.40 0.50 0.60
RTC/Area
% R
educ
tion
in R
unof
f
P1
P10
P50
Figure 4.4: %Reduction in Runoff versus the Rooftop Cover
Figure 4.4 also shows that the reduction in runoff follows a specific pattern, where all
curves tend to emanate from a rooftop cover equaling 5.5-6% of the ecoblock area.
Below this threshold there would be no observed effect for green roofs on runoff or peak
43
flows. As such, green roofs would not produce any reductions in runoffs or peak flows in
areas with sparse buildings like rural areas. Additionally, Novotny (2003) noted that the
CSO initiating rainfall intensity for typical US conditions is about 1 mm/hr, which is far
less than the intensities of the considered designed storms: 6 mm/hr for the one-year
storm, 12 mm/hr for the ten-year storm and 26 mm/hr for the fifty-year storm. As such,
green roofs could eliminate many CSOs.
However, while green roofs produce some significant peak flow shaving and drop in
runoff volume (and probably eliminate many CSOs), it cannot be solely relied upon for
stormwater management in a subwatershed or urban area. The little reductions for large
storm events mean that there would hardy be any economic benefits through decreasing
the sizing of culverts and pipes which are designed for such large events. In order to
achieve better runoff reductions and economic savings, stormwater management policies
should coupled vegetated roofs with green walkways or rain gardens which will reduce
the impact of areas directly connected to the storm sewer system.
4.4- Direct Energy Savings with Green Roofs
A more economically relevant attribute of green roofs is energy and insulation. Vegetated
roofs act to reduce the temperature of the roof surface through leaf shading direct solar
radiation, evaporation of moisture content and transpiration of plants which cool the
ambient air above the roof. Research by Wong et al. (2003) suggests that significant
savings in energy can be reaped with the use of green roofs and that plays an important
role in life cycle assessments of green roofs.
Carter and Keeler (2007) reported an insulating value (R-value) for the tested green roof
equal to 2.8 K.m2/W and similar to an inch of fiberboard. The R-value, a measure of
44
thermal resistance, describes the effectiveness of a material as a thermal insulator while
the inverse of R, the U-value or the coefficient of thermal conductivity, describes the rate
at which heat flows through the material with no regard to the heat source. Carter derived
the R-value with a second experimental roof, automated in situ measurement of radiation
and temperature and building energy models. Cost savings from additional insulation
provided by green roofs and the drop in heating and cooling loads will be computed by
the fundamental heat transfer equation:
Q (in Watts) = U×A×ΔT or (1/R) ×A×ΔT (4.1)
where A is the area of green roofs inside the ecoblock (GRA) and ΔT is the temperature
difference between the outdoor and the indoor environments. An average ΔT of 12°C or
K (21°F) was computed for Boston by assuming an indoor temperature of 72°F and
averaging the deviations from the monthly average temperatures. This computation is
shown in table 4.7.
Table 4.7: Computation of Average ΔT
Month Average Temperature* (°F) ΔT**
January 29 43 February 31.5 40.5 March 38.5 33.5 April 48.5 23.5 May 58.5 13.5 June 68 4 July 73.5 1.5
August 72 0 September 65 7
October 54 18 November 45 27 December 35 37
Average ΔT 21°F or 12°C* Mean of average high and average low (NOAA, 2008)
** With respect to an indoor temperature of 72 °F
45
Table 4.8: Yearly Energy Savings Provided by Green Roofs Ecoblock Energy Savings (MWh/yr)
1 3,950 2 2,570 3 6,940 4 7,220 5 3,430 6 9,670 7 18,750 8 18,360 9 17,820 10 33,930 11 6,070 12 6,520 13 13,460 14 20,680 15 24,100 16 33,780 17 52,520 18 70,640 19 88,470 20 122,400 21 128,470
Having ΔT, GRA and R, the yearly energy savings by green roofs in kWh were computed
for the ecoblocks using equation 4.1 based on 8760 hours per year of heating/cooling and
the results tabulated in table 4.8. When a kWh is converted into its dollar equivalent, it
would be found that green roofs have a yearly energy savings of $6.76 /m2.
Q (in kWh) = GRA37.54 or kWh/m 5437K 12GRAW/kW 1000hr/yr 8760
/WK.m 821 2
2 ×=××× ..
Additional unquantified cooling is provided by green roofs during the summer, since the
retained water (computed in section 4.2) would evaporate and absorb heat in the process
(the latent heat of water – the amount of heat absorbed or released during a phase change
– is 2260 J/g or 540 calories/g).
46
A computation of the total DES (Direct Energy Savings) combining direct savings from
hot water conservation, energy conservation, CFLs and the above computed savings from
green roofs can now be done. The DES for the ecoblocks are shown below in table 4.9.
Table 4.9: Total Direct Energy Savings in Ecoblocks
Ecoblock DES (MWh/yr) 1 11,570 2 8,010 3 18,090 4 26,150 5 12,080 6 24,330 7 57,580 8 53,890 9 39,510 10 94,600 11 13,770 12 19,580 13 37,670 14 57,250 15 69,210 16 100,230 17 157,800 18 211,220 19 250,730 20 345,340 21 359,110
4.5- Cost Considerations
Carter reported a cost of $116.76/m2 for the tested green roof, a figure which would be
used to calculate the cost of green roofing within the different ecoblocks. However, since
this cost is pertinent only to Athens, GA where the roof was tested, a locational
adjustment factor is needed to render this cost usable in subsequent calculations. Such
factor was estimated from RS Means (2008) for materials and workmanship between
Atlanta, GA and Boston, MA to be 1.3. In other words, civil engineering works in Boston
47
cost 30% more than Atlanta. The final adjusted costs of green roofs are presented in table
4.10.
Table 4.10: Cost of Green Roofs Ecoblock Cost of Green Roofs ($)
1 15,970,530 2 10,390,190 3 28,063,020 4 29,175,630 5 13,856,420 6 39,116,370 7 75,804,450 8 74,215,980 9 72,064,240 10 137,192,980 11 24,548,220 12 26,360,720 13 54,423,740 14 83,599,370 15 97,455,790 16 136,572,160 17 212,376,610 18 285,636,330 19 357,700,570 20 494,893,540 21 519,441,760
48
CHAPTER 5
WATER SUPPLY, RECLAMATION AND REUSE
The water supply and wastewater treatment in the urban green clusters or ecoblocks
would follow the principles of water conservation for the supply and water reuse for the
treatment.
5.1- Water Supply
Massachusetts regulations (#8810) (Division of Water Supply, 1989) stipulate that water
supply systems should be designed for a residential indoor water use of 100 gallons per
capita per day. This number figures heavily in the literature and has been recommended
by as well by the American Water Works Association (AWWA, 1999) and Metcalf and
Eddy (2003). A typical breakdown of the 100 gallons per day is shown in table 5.1.
Table 5.1: Typical Distribution of Residential Water Use
(Metcalf and Eddy, 2003 and AWWA, 1999) Percent of Total
Use Range Typical Shower 12-20 16.8
Bath 1-3 1.7 Faucet 12-18 15.7
Dishwashing 1-2 1.4 Clothes Washing 12-28 21.8 Other Domestic 0-9 2.2 Toilet Flushing 23-31 26.7
Leakage 5-22 13.7 Total 100
However, if regulations are changed in order to account for water conservation, 20
gallons/cap/day - which can be conserved in residential buildings as demonstrated in
49
chapter 3 - can be deducted which reduces the required residential water supply to 80
gallons/cap/day.
For commercial and industrial water supply, the required supply rate is typically not
regulated as actual data is mostly used for assessing the water necessity of the facility
being developed. Such data is provided in table 5.2 along with typical values and how far
consumption can be reduced by water conservation.
Table 5.2: Typical Flow Rates for Commercial and Institutional Buildings (Metcalf and Eddy, 2003)
Flow Rate gal/(unit.day) Facility Range Typical With Conservation Airport 3-5 4 3
Conference Center 6-10 8 6
Hotel 65-75 (Guest) 8-15 (Employee)
70 (Guest) 10 (Employee)
55 (Guest) 8 (Employee)
Office 7-16 13 9 Restaurant 7-10 8 5
Shopping Center 7-13 10 9
Hospital 175-400 (Bed) 5-15 (Employee)
250 (Bed) 10 (Employee)
200 (Bed) 8 (Employee)
School 15-30 25 15 Industrial Building
(Sanitary Use) 15-35 20
16
After studying the land use in the city of Boston using GIS, it was concluded that it’s
highly variable. A weighted average of 40 gal/cap/day was estimated as an appropriate
water supply flow rate for commercial and institutional buildings. Applying the
provisions of water conservation for commercial structures developed in chapter 3, 10
gal/cap/day can be conserved and as such the supply rate can be dropped to 30
gal/cap/day. Finally, using 80 gal/cap/day for residences, 30 gal/cap/day for commercial
establishments and 16 gal/cap/day for industrial sanitary use, and multiplying these
50
figures by the land use percentages and the population of each ecoblock, the water supply
requirement for each ecoblock can be computed. The results are shown in table 5.3.
Table 5.3: Water Supply Flow Rate
Ecoblock Water Supply Rate (MGD) 1 0.223 2 0.182 3 0.295 4 0.744 5 0.388 6 0.128 7 1.195 8 1.187 9 0.054 10 1.263 11 0.075 12 0.410 13 0.716 14 1.093 15 1.001 16 1.642 17 2.847 18 4.015 19 3.791 20 5.029 21 5.037
5.2- Wastewater Treatment and Reuse
In green urban clusters, wastewater should be treated in order to have a high quality
effluent suitable for reuse. Wilson (2008) claimed that it takes around 6400 kWh per MG
(or $14 per MG) of energy to treat wastewater to acceptable levels of nitrogen and BOD
and any wastage of wastewater is wastage of energy. McCarty (2008) even went further
and called wastewater a resource.
One of the popular treatment processes to reclaim water for restricted uses is the
Biological Nutrients Removal process (BNR) (with filtration). Other technologies include
51
ANNAMOX and Membrane Bioreactors, along with activated sludge. The quality
provided by BNR for disinfected tertiary effluents as compared to the EPA guidelines for
water reuse is provided in table 5.4.
Table 5.4: Effluent Quality Provided by BNR
Types of Reuse EPA Suggested Guidelinesa
Typical Effluent Quality using BNR (Disinfected
Tertiary)b
Urban Reuse (Landscape
Irrigation, Toilet Flushing and Fire
Protection)
Recreational Impoundments
pH 6-9
BOD5 ≤ 10 mg/L
Turbidity ≤ 2 NTU
E. coli = none
Residual Chlorine ≥ 1 mg/L
TSS ≤ 10 mg/L
BOD5 ≤ 5 mg/L
COD ≤ 20-30 mg/L
Total N ≤ 5 mg/L
NH3-N ≤ 2 mg/L
PO4-P ≤ 2 mg/L
Turbidity ≤ 0.3-2 NTU
a US EPA (1992)
b Metcalf and Eddy (2003)
Assuming that each ecoblock will have a water reclamation facility in order to maximize
environmental independence, a plant incorporating BNR will need to be provided at a
convenient location that enhances water reuse such as next to a park, golf course or
recreational facility. The cost of the water reclamation facilities will be estimated using
wastewater treatment plant construction curves supplied by Carollo Engineers. The
curves to be used are shown in figure 5.1. The design flow will be used as the double of
indoor water use (calculated as the water supply rate) in order to account for infiltration
and inflow. The factor of 2 was used by MWRA in order to design their facilities
(MWRA, 2006).
52
C = -14200Q2 + 5e6Q + 2e6R2 = 0.92
1,000,000
10,000,000
100,000,000
1,000,000,000
0.1 1.0 10.0 100.0Design Flow (MGD)
Tota
l Con
stru
ctio
n C
ost (
$)
BNR Plants
Poly. (BNR Plants)
ENR CCI Index = 7900
Figure 5.1: Construction Cost Curve for BNR Water Reclamation Facilities
(Carollo Engineers, 2007)
The curve above is the result of nationwide treatment plant projects and the points in
figure 5.1 do not pertain to a specific region of the United States; thus no location
adjustment factors were applied to the costs. Adjustment factors, however, were needed
for the ENR cost index, a yearly cost index maintained by the Engineering News Record
and used as a benchmark to account for inflation. Since the current index stands at 8100,
costs will be multiplied by a factor of 8100/7900. By polynomial regression of the cost C
versus the flow Q, the following equation was obtained with an R2 of 0.92:
C = -14200Q2 + 5×106Q + 2×106 (5.1)
Using Q as twice the amount of flow supplied for indoor water use and making the
necessary adjustments, the capital costs of the Water Reclamation Facilities for the
different sizes of ecoblocks were computed. The results are shown in table 5.5.
53
Additionally, a yearly cost for water management within the ecoblock should be
calculated to account for supply, distribution, pumping and treatment up the reuse
standards. As shown in table C.1 in appendix C, Wilson (2008) reported an energy
requirement of 10470 kWh per million gallons of water in order to supply water and then
reclaim it in a treatment facility in Massachusetts. The Energy Information
Administration also reported that a kWh of energy (electricity) in Boston costs $0.1938
and is sold to customers at $0.2017 (EIA, 2006). Using the figures above, yearly
operational costs to cover water supply and treatment in the ecoblocks were computed
and are also presented below in table 5.5.
Table 5.5: Capital Costs of Water Reclamation Facilities and Yearly
Ecoblock Capital Cost Of WRF ($)
Yearly Operational Cost (Supply and Treatment)
1 4,330,220 164,870 2 3,912,690 134,640 3 5,067,090 218,250 4 9,649,950 551,250 5 6,015,190 287,000 6 3,359,340 94,600 7 14,219,180 884,980 8 14,142,270 879,340 9 2,603,920 39,980 10 14,902,840 935,060 11 2,816,320 55,330 12 6,243,310 303,560 13 9,367,130 530,650 14 13,192,470 809,840 15 12,259,100 741,610 16 18,731,900 1,216,280 17 30,764,530 2,108,180 18 42,282,420 2,973,890 19 40,087,080 2,807,960 20 52,145,060 3,724,,880 21 52,217,860 3,730,460
54
CHAPTER 6
ALTERNATIVE ENERGY & IRM
Since the proposed environmentally viable urban clusters or ecoblocks should conform to
principles of limited impact development, resource conservation and management, and
enhancing the quality of life in a way that doesn’t heavily impinge on the natural
environment, this chapter will explore the potential to harvest energy from sources
alternative to the conventional ones such as oil, coal and natural gas. Alternative energy
sources are central to strategies of integrated resource management (IRM) and include
waste streams such as raw sewage and wet organic waste. A schematic of an IRM
strategy prepared for the province of British Columbia, Canada by Aquatex Scientific
Consulting (2008) is shown in figure 6.1. This figure indicates that IRM is a concept
aimed at reinforcing the integration of waste streams, maximizing reuse and potentially
generating zero waste. The following sections deal with two processes from figure 6.1:
biogas production from anaerobic digestion and heat extraction from wastewater.
6.1- Anaerobic Digestion and Biogas Production
Anaerobic digestion is a process in which anaerobic bacteria decompose biodegradable
matter and some inorganic matter (principally sulfate) in the absence of molecular
oxygen. The most widespread use of anaerobic digestion is its usage to treat the sludge
resulting from wastewater treatment processes such as primary and secondary clarifiers
where it provides volume and mass reduction of the feed sludge, and stabilization of the
biosolids, thus reducing the amount of solids which is otherwise landfilled or incinerated.
55
Figure 6.1: Integrated Resource Management in BC (Aquatex, 2008)
McCarty (2008) hailed anaerobic digestion as an “attractive component of sustainable
alternatives”. Anaerobic digestion’s major environmental benefit is the reduction of
greenhouse gases (GHG) emissions. Methane produced from anaerobic digestion - the
major component of biogas - can be used to replace energy derived from fossil fuels.
Despite the need to combust this methane to produce power, the generated carbon from
biodegradable matter is a part of the carbon cycle and has at some point been removed by
plants from the atmosphere via photosynthesis in order for them to grow. On the other
hand, the combustion of carbon in fossil fuels which has been sequestered for millions of
years elevates the overall levels of carbon dioxide in the atmosphere and contributes to
global warming.
The process of anaerobic digestion is shown in figure 6.2. First, the waste undergoes
hydrolysis where complex molecules are broken down into simple sugars and monomers,
making them bio-available to fermentative bacteria that produce hydrogen, acetate and
56
CO2. In the final stage, methanogenic bacteria convert the above intermediate products
into methane, carbon dioxide and water (the major components of biogas).
Figure 6.2: Stages of Anaerobic Digestion (source: epa.gov)
Biogas is the ultimate waste product of the bacteria feeding off the input biodegradable
feedstock. This gas is about 65 to 70% methane by volume, 25 to 30% carbon dioxide,
and the rest contains hydrogen, hydrogen sulfide and traces of nitrogen and oxygen
(Metcalf and Eddy, 2003). Biogas is used in Stockholm to generate heat and electricity on
a district level, run dozens of buses and gradually displace the use of ethanol or diesel
(Lucey, 2007). Gas production is calculated using stochiometry and rate of destruction of
volatile suspended solids - parameters specific to the design of each plant - but typical
values vary from 0.75 to 1.12 m3 / kg VSS or 1 ft3/person/day for (Metcalf and Eddy,
2003). The heat of combustion of biogas is approximately 22400 kJ/m3 compared to
37300 for natural gas which is a mixture of methane, butane and propane (Metcalf and
Eddy, 2003). Using the above figures, the energy in kWh which can be collected yearly
from the combustion of biogas for the various ecoblocks were calculated and tabulated
below in table 6.1.
57
Table 6.1: Energy from Anaerobic Digestion of Sludge Ecoblock Biogas Production (m3/year) Energy (kWh/year)
1 44,250 275,340 2 34,470 214,500 3 51,330 319,400 4 139,890 870,410 5 62,460 388,670 6 61,120 380,310 7 241,350 1,501,760 8 207,010 1,288,090 9 50,040 311,360 10 323,700 2,014,110 11 20,700 128,830 12 78,720 489,840 13 130,060 809,250 14 192,520 1,197,920 15 253,640 1,578,230 16 393,530 2,448,650 17 634,890 3,950,400 18 841,900 5,238,500 19 891,940 5,549,860 20 1,215,640 7,563,970 21 1,236,340 7,692,800
The use of wastewater sludge to produce energy or biofuels was also recommended by
James Bernard, winner of the 2007 Clarke Prize (Barnard, 2007).
6.2- Heat Extraction
Energy from biogas combustion is primarily in the form of electricity. A more sustainable
way to harvest heat is direct extraction from wastewater using a heat pump. Stockholm’s
energy company “Fortum Energi” extracts heat from treated sewage to provide heat and
hot water to over 80,000 apartments (Lucey, 2007). Thousands of kWh of thermal energy
are lost when the effluent is discharged from treatment plants, and as such sewer heat
represents an untapped energy source (McBride, 2008). A heat recovery system consists
of two parts: a heat exchange system and a heat pump (Harvard Green Campus Initiative,
58
2008). The heat exchange system is a series of closed-loop tubes where a water-alcohol
mixture is heated by sewage while the heat pump extracts heat from the mixture.
Generally, a heat pump is a machine that moves heat from a low temperature heat source
to a higher temperature heat sink by applying work (ASHRAE Handbook, 2004). This
heat can be used for heating buildings or industrial processes or to provide domestic hot
water. However, a heat pump can operate in a cooling mode as well, where in this case
the heat source is the indoor space and the heat sink is the outdoor surrounding. The
process of heat extraction is shown in a simplified loop diagram in figure 6.3. The
working fluid or mixture is first compressed, heated and highly pressurized, and therefore
discharges heat to the surrounding space (or sink). After it condenses to a moderate
temperature and loses pressure in an expansion valve, the fluid is evaporated thereby
absorbing heat from the surrounding space (or heat source). The cycle is capped off by a
return to the compressor.
Figure 6.3: Thermodynamic Cycle of Heat Extraction (Wikipedia.com)
In this study, the heat source will be raw or treated sewage at the water reclamation
facility, although some systems are capable of recovering heat from individual sewer
mains. McBride (2008) and the Harvard Green Campus Initiative report that the most
prominent vendor of heat recovery systems is a Swiss firm called “Rabtherm”.
59
Rabtherm’s systems have been installed worldwide and have been deemed usable for an
extensive system across the sewers of the Great Vancouver Regional District, BC,
Canada (Compass Resource Management, 2005). Harvard’s Green Campus Initiative and
Rabtherm report that this system extracts 2.3 kWh of energy per m3 of sewage and costs
around $300,000 to install (per 36 m of sewer) and around $0.82 per kWh to operate.
When a Rabtherm heat extraction is installed at the water reclamation facilities in the
ecoblocks, the amounts of energy shown in table 6.2 can be extracted annually from the
wastewater generated in the cluster. The operational costs were also calculated.
Table 6.2: Heat Extracted from Sewage
Ecoblock Heat Extracted from Sewage (kWh/year)
Yearly Operational Cost ($/year)
1 707,350 580,030 2 577,660 473,680 3 936,380 767,830 4 2,365,070 1,939,360 5 1,231,350 1,009,710 6 405,870 332,810 7 3,796,880 3,113,440 8 3,772,710 3,093,620 9 171,520 140,650 10 4,011,750 3,289,640 11 237,390 194,660 12 1,302,370 1,067,940 13 2,276,690 1,866,890 14 3,474,500 2,849,090 15 3,181,760 2,609,040 16 5,218,300 4,279,010 17 9,044,850 7,416,780 18 12,759,080 10,462,450 19 12,047,160 9,878,670 20 15,981,100 13,104,500 21 16,005,020 13,124,120
Another heat extraction technology recommended by the Harvard Green Campus
Initiative is the use of ground source heat pumps to harvest geothermal energy.
60
CHAPTER 7
TBL & LCC ASSESSMENTS
7.1- Triple Bottom Line Assessment
A Triple Bottom Line approach (TBL) which - as explained in chapter 1 - examines the
financial, ecological and social dimensions of projects, is a tool to evaluate the relative
sustainability of options for urban water management (Taylor and Fletcher, 2005;
Novotny 2007). Originally coined by Elkington (1997), TBL is a flexible and practical
tool used for corporate planning, utility managing and city development, besides the main
use as a benchmark of sustainability. It also incorporates an element of stakeholder
participation (Environment Australia, 2003). The following tables constitute a TBL
evaluation of the sustainable management and green practices proposed in chapters 3 to
6. Table 7.1 summarizes how the components of this study contribute to environmental
protection and enhancement. It shows the volumes of water that can be saved annually,
the amount of energy that is conserved on a yearly basis and peak flow reductions for the
1-year six-hour storm. The offset emissions of GHG were calculated based on data from
the Energy Information Administration (2007) where the Department of Energy reported
that a MWh of energy in Massachusetts (and neighboring states in New England) is
equivalent to 466 kg of CO2, 0.0265 kg of CH4, and 0.0062 kg of N2O. Table 7.1
demonstrates that major savings in resources - a major component of sustainability -
equaling about 15-25% of the current consumption can be achieved.
The contribution of the proposed practices to social welfare is shown in table 7.2. The
estimated savings in bills are estimated from the current rates for water and electricity.
61
Table 7.1: Environmental Benefits Water Conserved (m3/yr) Energy Conserved (MWh/yr) Offset GHG Emissions
Ecoblock Conservation + Reuse Green Roofs Conservation +
IRM Green Roofs
Peak Flow Reduction (%) (1-yr 6-hr storm) CO2 (Tons/yr) CH4 (kg/yr) N2O (kg/yr)
1** 21,290 87,800 8,630 4,000 17 3,550 200 50 2 43,220 57,120 6,290 2,600 20 4,080 230 50 3 67,510 154,290 12,490 7,020 25 7,760 440 100 4 207,530 160,400 22,420 7,300 32.5 16,920 960 220 5 88,500 76,180 10,380 3,470 35 7,490 430 100 6 60,708 215,050 15,520 9,780 23.7 8,440 480 110 7 390,310 416,760 44,610 18,970 32.8 33,890 1,930 450 8 307,110 408,030 40,970 18,580 26 28,780 1,640 380 9 15,780 396,200 22,190 18,030 10.2 9,540 540 130 10 328,800 754,260 67,100 34,330 27.7 37,830 2,150 500 11 11,840 134,960 8,080 6,140 15.3 3,720 210 50 12 67,340 144,930 14,940 6,600 NC* 7,810 440 100 13 135,240 299,210 27,460 13,620 NC* 15,610 890 210 14 223,860 459,610 41,520 20,920 NC* 24,880 1,410 330 15 278,660 535,790 50,210 24,380 NC* 29,710 1,690 390 16 450,220 750,850 74,680 34,180 NC* 45,550 2,590 600 17 826,470 1,167,600 119,300 53,140 NC* 78,640 4,470 1,040 18 1,134,220 1,570,370 159,990 71,470 NC* 107,330 6,100 1,420 19 896,450 1,966,570 180,980 89,510 NC* 101,780 5,780 1,350 20 1,228,290 2,720,830 248,010 123,840 NC* 139,750 7,940 1,850
21** 1,216,160 2,855,790 255,850 129,980 23.2 141,990 8,070 1,880 * Not Computed **Ecoblocks were described in Chapter 2 (tables 2.1, 2.2 and 2.4). Ecoblocks 1 to 5 represent small urban developments while ecoblocks 19 to
21represent large city centers or business districts
62
Other unquantified social benefits include:
- increase in property value
- better air quality and healthier lives
- less flooding and thus less hindrance to people’s commutes
Table 7.2: Social Benefits
Ecoblock Money Saved Yearly in Water and Sewer Bills* ($)
Money Saved Yearly in Electricity Bills ($)
1 627,760 811,360 2 1,274,400 535,220 3 1,990,620 1,433,250 4 6,119,290 1,524,480 5 2,609,540 721,510 6 1,790,050 1,989,410 7 11,508,790 3,923,620 8 9,055,530 3,822,610 9 465,290 3,641,040 10 9,695,090 7,006,500 11 349,120 1,241,910 12 1,985,600 1,347,300 13 3,987,720 2,780,640 14 6,600,800 4,275,340 15 8,216,640 4,988,390 16 13,275,310 7,005,570 17 24,369,530 10,925,670 18 33,443,930 14,700,180 19 26,432,970 18,277,700 20 36,217,700 25,284,970 21 35,860,030 26,520,880
* Based on the 2008 rates set by Boston Water and Sewer Commission
In computing the savings above, only water saved by conservation (WSC) was accounted
for in the reductions of water and sewer bills, while only direct energy savings (DES),
were factored into the reductions of electricity bills. These categories generate the
savings at the end of both the consumer and the service provider, while the rest only
generate savings at the end of the provider.
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Table 7.3 tallies the benefits of sustainable management from a strictly economic
perspective. Until the end of the last century, economics and profitability were the single
bottom line for urban development (Novotny, 2007). Presently, the economic aspect is
still important, but it has to be complemented by environmental and social welfare
aspects for the policy/project to be judged as sustainable. The savings were calculated
based on the quoted dollar-equivalents for a supplied volume of water, a treated volume
of water and a provided kWh of energy. For instance, MWRA (2007) reported that it
costs the agency $0.6341 per m3 of water supply and $0.7266 per m3 of wastewater
treatment. Also, the Energy Information Administration reported that a kWh of energy in
Boston costs $0.1938. The yearly savings, computed from the aforementioned figures,
will comprise the basis for the Life Cycle Cost Assessment (LCCA) to follow. The
savings were divided as in table 7.3 because different scenarios will be considered in the
LCCA.
Moreover, at this stage, tallying the benefits allows some comparison between the
different components of sustainable management in this study. First, table 7.1 reveals that
the volume of water retained by green roofs far exceeds the volume that can be saved by
conservation. This highlights the importance of green roofs in reducing urban runoff and
preventing a large part from ending up in combined sewers and eventually being treated
at water reclamation plant. This also translated into higher yearly savings in wastewater
treatment for green roofs in table 7.3. However, from an energy perspective, green roofs
(with their direct and indirect energy savings) fell short against energy conservation
which proved to be the most significant source of savings among the proposed
components of sustainable management.
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Table 7.3: Economic Benefits (All Amounts are in US $)
Ecoblock Savings in Water Supply (Conservation + Reuse)
Savings in Wastewater Treatment
(Conservation + Reuse)
Savings in Wastewater Treatment
(Green Roofs)
Savings in Energy (Conservation + IRM)
Savings in Energy (Green Roofs)
1 13,500 15,470 63,800 1,672,330 774,500 2 27,400 31,400 41,500 1,218,190 503,910 3 42,800 49,050 112,110 2,420,490 1,360,770 4 131,600 150,790 116,550 4,345,610 1,415,660 5 56,120 64,300 55,350 2,011,630 672,530 6 38,500 44,110 156,260 3,008,080 1,896,070 7 247,500 283,600 302,820 8,646,060 3,676,430 8 194,740 223,150 296,480 7,940,400 3,599,950 9 10,000 11,407 287,880 4,300,900 3,494,090 10 208,500 238,900 548,050 13,004,780 6,652,870 11 7,500 8,600 98,060 1,566,080 1,190,190 12 42,700 48,930 105,310 2,894,560 1,278,420 13 85,750 98,270 217,410 5,322,500 2,639,190 14 141,950 162,660 333,950 8,046,650 4,054,850 15 176,700 202,470 389,310 9,731,860 4,725,450 16 285,490 327,130 545,570 14,472,210 6,623,450 17 524,070 600,510 848,380 23,120,630 10,297,940 18 719,200 824,120 1,141,030 31,005,280 13,850,840 19 568,440 651,360 1,428,910 35,072,020 17,346,860 20 778,860 892,480 1,976,960 48,064,390 23,999,740 21 771,170 883,660 2,075,020 49,583,340 25,189,930
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Furthermore, table 7.3 reveals that savings in energy (not just conservation) constitute the
major part of the total savings in each ecoblock. The percentage of energy-related savings
(last two columns) ranges from 0.94 to 0.96 i.e. nearly 95% of the yearly savings. Indirect
energy savings (IES) constitute 0.5% to 0.6% only of the total energy savings with the
DES being much more significant. For green roofs in particular, the TBL assessment also
shows that indirect energy savings are also marginal (1.2% of the total energy savings)
and that energy-related savings are much greater that water-related savings.
7.2- Life Cycle Cost Assessment
A Life Cycle Cost Analysis (LCCA) economically evaluates an alternative or a scenario
over its entire system life span, by computing the net present worth (NPW) of the
alternative, the annual worth, or the benefit/cost ratio (Blank and Tarquin, 2002). An
LCCA differs from ordinary cost estimating in that all costs from the onset of the project
or alternative through the operation are estimated. The life is assumed to end whenever a
major change, maintenance or refurbishment is needed or applied. In this study, a life
cycle of 40 years will be used since green roofs have a service life of years (Carter and
Keeler, 2007) and a water reclamation facility will need an overhaul in 40 years as well.
Parameters to be computed will be the incremental NPW and the payback period (PBP).
The incremental NPW is the NPW of a cash flow diagram representing the difference in
expenses and returns between a sustainable integrated resource management alternative
and conventional resource management (no green roofs, no conservation, no reuse and no
semiautonomous ecoblocks). A diagram of an incremental economic analysis is shown in
figure 7.1. In this study, alternative A can be thought of as the sustainable option while
alternative B represents the status quo or the “do-nothing” alternative. Since, in
66
conventional resource management, costs associated with decentralized water
reclamation, green roofs and alternative energy are virtually nonexistent, the initial
investment in the final cash flow diagram would be cost associated with sustainable
management (B0 = 0). In other words, costs common to both alternatives would not be
considered in the analysis such as expenses to develop the buildings inside the ecoblocks,
additional water required by industries and costs related to sewerage, piping or heavy
construction. In the same logic, the status quo does not yield any benefits or savings nor
does not carry any cost for effective management. Therefore, yearly benefits in the final
cash flow diagram would be the savings generated by sustainable management, and
yearly expenses will comprise of the operational costs of the water reclamation facilities
and renewable energy. Since the efficient fixtures and appliances enumerated in chapter 3
were at a no to minimal additional cost, their initial cost - from an incremental
perspective - would be nil.
Figure 7.1: Incremental Cash Flow Diagram
67
All in all, the question that needs to be answered is whether the savings generated by
green roofs, conservation and renewable energy can recover the additional cost invested
in sustainable management. This is of particular interest to developers who would want to
know if the extra investment needed will be able to recover itself and generate profits.
When the initial cost and the annual benefits and expenses are known, an economic
analysis can determine the NPW and the PBP at a selected discounting rate. Appropriate
discounting rates for such LCCA should be within 3-6% (Carter, 2007). Subsequently, a
discounting rate of 5% would be used in the computations to follow. The economic
analysis can be performed using the functionalities of Excel or MATLAB, or with more
targeted and advanced programs such as BEES (Building for Environmental and
Economic Sustainability). BEES, developed by the NIST (National Institute of Standards
and Technology), is mostly used to optimize the sustainability of buildings through life
cycle assessment from raw material acquisition through manufacture, installation, use and
up to recycling and waste management (NIST, 2007).
7.2.1- Vegetated Roofs Only
Since vegetated roofs have shown to yield substantial savings in energy and water, they
will be investigated as a sole component of sustainable management. In this first
scenario, the initial investment would be the cost of green-roofing and the yearly
expenses are nil since the extensive green roof proposed by Carter is virtually
maintenance-free. Annual benefits include the direct and indirect energy savings as well
as savings in wastewater treatment. These cash flows along with the incremental NPW
and PBP of this alternative are shown in table 7.4. The results of this scenario indicate
that investing in green roofs only would be a short-sighted and a cash-strapping decision.
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Table 7.4: Economic Analysis with Green Roofs Only
Ecoblock Initial Cost ($)
Annual Benefits (S)
Annual Expenses ($)
NPW ($) (40 yr / 5%)
1 15,970,530 838,300 --- -1,586,060 2 10,390,190 545,410 --- -1,031,450 3 28,063,020 1,472,880 --- -2,789,730 4 29,175,630 1,532,210 --- -2,884,290 5 13,856,420 727,880 --- -1,366,650 6 39,116,370 2,052,330 --- -3,900,230 7 75,804,450 3,979,250 --- -7,524,100 8 74,215,980 3,896,430 --- -7,356,750 9 72,064,240 3,781,970 --- -7,169,040 10 137,192,980 7,200,920 --- -13,631,670 11 24,548,220 1,288,250 --- -2,443,010 12 26,360,720 1,383,730 --- -2,617,160 13 54,423,740 2,856,600 --- -5,407,060 14 83,599,370 4,388,800 --- -8,291,510 15 97,455,790 5,114,760 --- -9,691,110 16 136,572,160 7,169,020 --- -13,558,230 17 212,376,610 11,146,320 --- -21,115,790 18 285,636,330 14,991,870 --- -28,389,330 19 357,700,570 18,775,770 --- -35,525,260 20 494,893,540 25,976,700 --- -49,156,750 21 519,441,760 27,264,950 --- -51,599,760
The sign convention for the computations above and all economic computations to follow
is negative signs for all costs and positive signs for all profits. NPW for this scenario
proved to be negative for all sizes of ecoblocks and various land uses and characteristics
therein. Hence, green-roofing by itself, despite producing appreciable savings in energy,
water and peak flow reduction, is neither enough to solve the problem of urban runoff (as
established in chapter 4) nor it would, purely on its own, recover the cost of the
investment during the life cycle. Since the NPWs were negative, calculating the PBPs
would be irrelevant but estimating yields a time span of about 63 years, which means that
69
the green roof has to be able to last nearly 23 years beyond its assumed service life for
green-roofing to become economically feasible. And from an absolute feasibility
perspective, if green-roofing were to be implemented by cities or private developers, it
would be “more feasible” or less of a loss in the case of small developments (university
campuses, housing developments,…) or small urban clusters as shown for ecoblocks 1
and 2 where at the end of the life cycle, the NPW is merely a million or a million and a
half dollars off of breaking even. Moreover, if green roofs are used in housing
compounds or university campuses, then additional revenues from increased attraction of
enrollment may be able to make the investment viable there. But, for city-wide scales,
green roofs by themselves would be far off from being economically viable because of
the relatively high installation cost.
However, Carter (2007) admits that the cost of $116.76/m2 is at the high end of what
would be experienced for widespread green roof application as it ignores economies of
scale in materials purchasing and innovations in construction techniques (such as in
Germany where green roof construction industries have been established for 30 years).
Therefore, the actual cost could very well vary from 50% to 100% of the initial estimates.
Ever-rising energy prices could also increase the savings from green roofs. As such, a
sensitivity analysis will be conducted with two variables: the construction cost and
energy prices. Table 7.5 shows the NPWs with a construction cost of 75% the initial
estimate and an increase in energy costs of 8% per year. Therein, the results show that a
“green roofs only” scenario may not be doomed to fail. With energy prices increasing
every year, the importance of the energy savings brought about by vegetated roofs
becomes the driving factor for the NPW and flips it to the positive side quite easily,
70
making the alternative economically viable for all ecoblocks. Furthermore, not only did
table 7.5 reveal high sensitivity of the NPW to the energy costs but also to the
construction cost of the green roof. This demonstrates that if green roofs become a
common practice and a highly competitive business, costs will drop allowing developers
and cities to reap the benefits of green roofs during their life cycle with the PBP dropping
from 63 to 25 years. So in conclusion of this section, a “green roofs only” alternative
would not work without reduced construction costs and/or hikes in energy prices.
Table 7.5: Sensitivity Analysis with Green Roofs Only Scenario
Ecoblock NPW at 75% of the Construction Cost ($)
NPW with 8% annual increase in energy costs ($)
1 2,406,576 34,494,830 2 1,566,102 22,443,730 3 4,226,030 60,603,170 4 4,409,622 63,065,710 5 2,097,451 29,963,860 6 5,878,858 84,430,170 7 11,427,011 163,746,230 8 11,197,247 160,350,680 9 10,847,021 155,606,790 10 20,666,571 296,299,220 11 3,694,046 53,003,230 12 3,973,021 56,939,370 13 8,198,880 117,542,370 14 12,608,331 180,607,910 15 14,672,836 210,448,910 16 20,584,811 295,002,100 17 31,978,362 458,624,490 18 43,019,749 616,866,500 19 53,899,888 772,596,320 20 74,566,638 1,068,896,180 21 78,260,684 1,121,899,410
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This agrees with an economic analysis by Carter and Keeler (2007) for widespread green
roof application in the Tanyard Branch Watershed, east of Atlanta, GA. Carter and Keeler
also found - under different green-roofing scenarios - negative NPWs at the estimated
construction prices in Atlanta and current energy prices.
7.2.2- Vegetated Roofs and Energy Conservation
This second sustainable management scenario for urban development adds energy
conservation to the first, since the TBL assessment has shown that savings from energy
conservation surpass savings from water conservation. As such, it will be investigated in
this section if savings from energy conservation, when coupled with savings from green
roofs, would be able to make green-roofing economically viable. The calculation of the
NPWs is shown in table 7.6. The results show that the NPW for the various sizes of
development are not only positive - which makes the alternative economically feasible –
but also very comparable to the results shown in 7.2.1 for an annual 8% increase in
energy costs. This reemphasizes the importance of energy in affecting sustainable
resource management and shows that developers and urban planners do not need spikes
in energy costs to gain economic returns on policies requiring green roofs, but economic
returns or benefits can be realized within 5-8 years of the investment with further energy
conservation as described in chapter 3. Only direct energy savings (DES) by direct
conservation were used in the computations of this section. These savings require active
stakeholder participation and more stringent policies regarding efficient lighting and
home appliances. It has to also be noted that the first two scenarios addressed have not
tapped into the analysis of the ecoblocks themselves because the semi-autonomy in water
management (with water reclamation facilities) hasn’t figured in the two scenarios.
72
Rather, the ecoblocks are just mere indication that the higher the stakeholder participation
is, the greater the benefits will be and at this point should be thought of only as
implementation zones for the second scenario. And by examining the ecoblocks at this
point, one can make the observation that for clusters of comparable areas, the ones with
the higher NPWs have a high residential and commercial land use cover and high
population density, conditions conducive to larger green roof areas (and higher benefits
from green roofs) and potentially larger stakeholder participation.
Table 7.6: Economic Analysis with Green Roofs and Energy Conservation
Ecoblock Initial Cost ($)
Annual Benefits (S)
Annual Expenses ($)
NPW ($) (40 yr / 5%)
Payback Period (years)
1 15,970,530 1,476,760 --- 9,369,270 16.0 2 10,390,190 1,054,270 --- 7,700,170 14.0 3 28,063,020 2,160,870 --- 9,015,560 21.5 4 29,175,630 3,668,630 --- 33,774,830 10.5 5 13,856,420 1,676,370 --- 14,908,580 11.0 6 39,116,370 2,841,110 --- 9,634,490 24.0 7 75,804,450 7,525,250 --- 53,322,140 14.5 8 74,215,980 6,885,710 --- 43,936,680 16.0 9 72,064,240 4,203,520 --- 64,410.00 17.0 10 137,192,980 11,757,850 --- 64,561,080 18.0 11 24,548,220 1,492,260 --- 1,057,620 35.0 12 26,360,720 2,531,030 --- 17,069,440 15.0 13 54,423,740 4,691,900 --- 26,085,010 18.0 14 83,599,370 7,087,270 --- 38,011,740 18.0 15 97,455,790 8,742,320 --- 52,554,520 17.0 16 136,572,160 12,878,010 --- 84,402,900 15.5 17 212,376,610 20,403,260 --- 137,725,040 15.0 18 285,636,330 27,244,400 --- 181,853,120 15.0 19 357,700,570 31,445,990 --- 181,884,280 17.0 20 494,893,540 43,205,770 --- 246,478,620 17.5 21 519,441,760 44,698,030 --- 247,536,240 18.0
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For example, ecoblock 4, which has an area comparable to ecoblocks 1 to 5, has a much
higher population (13,500 persons) and a 74% residential and commercial land use and as
such more green roof people involved in energy conservation and that leads to a higher
NPW and a lower PBP. Ecoblock 4 has a PBP of only 10.5 while ecoblocks 6 and 11
have PBPs of 24 and 35 years respectively. Ecoblocks 6 and 11 have low residential land
covers (4% and 6% respectively) and as such lower benefits from residential energy
conservation and lower surface area available for green roofs. Also, ecoblock 11 has the
lowest population count (2,000 persons) and high transportation land cover (60%) and as
such not enough window for energy conservation to generate benefits at a rate that
quickly recovers the investment in vegetated roofs. On another note, the NPW increases
with the size of the zone of implementation as shown for the higher level ecoblocks, but
the PBP seems to stabilize at about 15-18 years.
7.2.3- Vegetated Roofs, Ecoblocks, IRM, Energy and Water Conservation
This scenario combines all the components of sustainable management incorporated in
this study. It adds to the second scenario water reclamation facilities (WRF) to make the
ecoblocks environmentally semiautonomous, and furthers energy conservation with water
conservation as discussed in chapter 3 and heat extraction as discussed in chapter 6. Since
it would be rather difficult to estimate the cost of anaerobic digestion, as too many factors
come into play (operating temperature, stochiometry, number and shape of digesters), the
added IRM component to the current scenario was only heat extraction from sewage.
Water conservation also requires an aspect of stakeholder participation and policies
encouraging the use of low flow fixtures. Additionally, besides being very important
from an environmental and water resources perspective, water conservation is
74
particularly needed in this scenario to help offset the capital and operation/maintenance
costs of the cluster WRF. Table 7.7 shows the results of the economic analysis of this
alternative. The initial cost now includes the cost of green-roofing, the cost of the WRF
in the ecoblock, and installtion of heat pumps. The annual expenses include the
operational costs of the WRF and heat exchangers while green roofs and conservation
programs have virtually no maintenance or operational costs. The annual benefits now
include all energy-related savings (DES and IES) and water-related savings.
Table 7.7: Economic Analysis with Green Roofs, Semiautonomous Ecoblocks, Water and Energy
Conservation and IRM
Ecoblock Initial Cost ($)
Annual Benefits (S)
Annual Expenses ($)
NPW ($) (40 yr / 5%)
Payback Period (years)
1 20,300,750 2,486,240 744,900 9,579,080 18.0 2 14,302,880 1,780,840 608,320 5,816,510 19.0 3 33,130,110 3,923,320 986,080 17,270,290 17.0 4 38,825,580 5,991,530 2,490,610 21,247,060 16.5 5 19,871,610 2,784,610 1,296,710 5,659,420 22.5 6 42,475,710 5,069,310 427,410 37,175,120 12.5 7 90,023,630 12,865,370 3,998,420 62,125,250 14.5 8 88,358,250 12,005,090 3,972,960 49,465,870 16.5 9 74,668,160 8,043,940 180,630 60,259,160 13.0 10 152,095,820 20,262,770 4,224,700 123,103,030 13.0 11 27,364,540 2,845,460 249,990 17,171,390 15.5 12 32,604,030 4,274,990 1,371,500 17,217,250 17.0 13 63,790,870 8,206,280 2,397,540 35,881,880 16.0 14 96,791,840 12,507,910 3,658,930 55,048,690 16.0 15 109,714,890 14,919,930 3,350,650 88,803,540 13.0 16 155,304,060 21,779,310 5,495,290 124,115,070 13.0 17 243,141,140 34,625,950 9,524,960 187,569,260 13.5 18 327,918,750 46,525,260 13,436,340 239,857,340 14.0 19 397,787,650 53,992,030 12,686,630 310,975,840 13.5 20 547,038,600 74,246,540 16,829,380 438,188,190 13.5 21 571,659,620 77,012,250 16,854,580 460,591,860 13.5
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The table above shows that the NPWs are still at the positive side, and have sharply
increased relative to the second scenario. The PBP now spans an interval from 12.5 to
22.5 years with a stable PBP of about 14 years for higher level ecoblocks. Ecoblocks 6
and 11, unlike in the previous alternative, seem to have decent PBPs due to the low
operational costs.
7.2.4- Vegetated Roofs, Ecoblocks, Water Conservation and Reuse
This scenario excludes energy conservation in order to investigate the feasibility of an
alternative revolving around water management. Green roofs were initially retained since
they proved to be effective in conserving water (table 7.1) but the NPW was also
calculated without green roofs. As such, initial and operational costs associated with
green roofs and WRFs, as well as benefits from water conservation, green roofs and reuse
were the components of the economic analysis of this alternative whose results are shown
in table 7.8 (this alternative assumes 25% reuse).
The economic analysis reveals that this alternative is not economically viable since the
NPWs are negative (and as such no PBPs were computed). When green roofs and their
benefits were taken out, the NPWs remained negative but numerically greater. This
shows that an alternative centered on water management does not generate enough
benefits with the elements of this study and the dollar-equivalency of water in Boston.
Singling out energy from a sustainable management plan could render this plan
unfeasible. Also, despite generating more savings than water conservation, the high
installation cost of vegetated roofs (which made the first alternative unfeasible), made the
NPWs plummet relative to a scenario which excludes green roofs. Without green roofs,
the benefits would drop but a more significant drop in the initial cost - which would only
76
include the WRF - made the NPW higher (or less negative). Therefore, if such a scenario
is to be adopted, green roofs should be eliminated and water management trimmed to
water reclamation, conservation and reuse. Nevertheless, the investment would not be
able to recover its cost in 40 years. Also, if such an alternative is to be adopted, the
smaller the ecoblock, the more economically sensible the investment becomes.
Table 7.8: Economic Analysis with Vegetated Roofs, Ecoblocks, Water Conservation and Reuse
Ecoblock Initial Cost ($)
Annual Benefits (S)
Annual Expenses ($)
NPW ($) (40 yr / 5%)
NPW ($) (40 yr / 5%)
No Green Roofs1 20,300,750 903,310 164,870 -7,323,700 -5,737,650 2 14,302,880 639,860 134,640 -5,383,740 -2,481,310 3 33,130,110 1,621,900 218,250 -8,639,474 -2,806,260 4 38,825,580 1,967,910 551,250 -13,493,517 -3,074,920 5 19,871,610 923,420 287,000 -8,418,416 -3,048,420 6 42,475,710 2,167,290 94,600 -6,734,670 -1,645,020 7 90,023,630 4,770,220 884,980 -21,713,401 -2,329,600 8 88,358,250 4,553,110 879,340 -23,687,025 -4,212,800 9 74,668,160 3,814,670 39,980 -9,823,657 -2,111,200 10 152,095,820 7,902,780 935,060 -30,799,980 -4,292,320 11 27,364,540 1,317,570 55,330 -5,602,911 -2,366,440 12 32,604,030 1,548,480 303,560 -10,678,696 -3,718,740 13 63,790,870 3,172,670 530,650 -17,471,063 -4,544,670 14 96,791,840 4,899,140 809,840 -25,119,669 -5,424,980 15 109,714,890 5,700,040 741,610 -23,255,766 -3,426,330 16 155,304,060 8,118,050 1,216,280 -34,617,694 -4,403,990 17 243,141,140 12,865,090 2,108,180 -54,648,112 -4,853,860 18 327,918,750 17,365,770 2,973,890 -75,445,644 -6,470,490 19 397,787,650 20,737,820 2,807,960 -84,914,075 -10,347,110 20 547,038,600 28,642,080 3,724,,880 -112,566,212 -11,780,360 21 571,659,620 29,911,940 3,730,460 -115,482,917 -12,119,000
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7.2.5- No Vegetated Roofs
Vegetated roofs had high installation or construction costs. Green-roofing an ecoblock
proved ten times more costly than a WRF in many ecoblocks which underlines the
importance of a scenario excluding vegetated roofs but including semiautonomous water
management, water and energy conservation and IRM. Table 7.9 shows the economic
analysis for this alternative. The initial cost now includes the cost of the WRF with heat
extraction and the annual expense includes their respective operational costs. Annual
benefits are now due mainly to water and energy conservation and reuse.
Table 7.9: Economic Analysis with No Green Roofs
Ecoblock Initial Cost ($)
Annual Benefits (S)
Annual Expenses ($)
NPW ($) (40 yr / 5%)
Payback Period (years)
1 4,633,910 1,647,940 744,900 10,861,350 6.0 2 4,191,340 1,235,420 608,320 6,569,200 8.5 3 5,467,640 2,450,440 986,080 19,659,400 4.5 4 10,063,590 4,459,320 2,490,610 23,717,640 6.0 5 6,429,010 2,056,720 1,296,710 6,612,120 11.5 6 4,282,790 3,016,980 427,410 40,151,970 2.0 7 15,605,520 8,886,120 3,998,420 68,262,960 3.5 8 15,423,470 8,108,660 3,972,960 55,541,430 4.5 9 5,183,780 4,261,970 180,630 64,848,310 1.5 10 17,482,110 13,061,850 4,224,700 134,155,390 2.0 11 3,501,170 1,557,220 249,990 18,929,640 3.0 12 6,825,640 2,891,260 1,371,500 19,252,120 5.5 13 10,350,010 5,349,690 2,397,540 40,306,150 4.0 14 14,589,170 8,119,110 3,658,930 61,943,450 3.5 15 14,579,250 9,805,170 3,350,650 96,174,540 2.5 16 21,465,690 14,610,280 5,495,290 134,939,340 2.5 17 34,884,660 23,479,630 9,524,960 204,564,840 2.5 18 47,683,750 31,533,380 13,436,340 262,845,200 3.0 19 48,068,260 35,216,260 12,686,630 338,519,880 2.5 20 62,705,510 48,269,840 16,829,380 476,784,430 2.5 21 63,463,160 49,747,300 16,854,580 500,946,380 2.0
78
The table above shows that this alternative has NPWs within 10% of the comprehensive
alternative of scenario 3 (section 7.2.3) and as such equally feasible. However, the PBPs
are about 10 years lower. That means that the cost of the WRF can be recovered
relatively quickly. This alternative is heavily dependent upon conservation and reuse
patterns as virtually all the savings come from energy and water savings. Therefore,
stakeholder participation and policies soliciting conservation are needed for the success
of this alternative. Generally, higher level ecoblocks showed faster payback periods
because of the strict reliance on conservation by the existing population. Nonetheless,
ecoblock 9 which had the lowest population density, no residences and dispersed
commercial and industrial buildings within, was bolstered by lower initial and operational
costs (relative to ecoblocks of a comparable area) and subsequently had the lowest PBP.
This means that this alternative, barring the difficulty in implementing it, is highly
adaptable to the environment in which it is implemented.
7.3- Analysis and Discussion
The LCCA was a necessary step in order to determine the feasibility of the different
alternatives proposed in the previous section. The TBL assessment tabulates social,
economical and environmental benefits for an alternative but does not account for initial
or operational costs. As such, the LCCA complements the TBL assessment by providing
further information and determining whether the proposed plan is economically viable. In
section 7.2, five scenarios were proposed and economically analyzed for their NPWs and
PBPs when applicable:
1) A green-roof-centric approach which is solely based on widespread vegetated
roofs application. This alternative proved to be unfeasible at the estimated
79
construction costs and current energy prices. Reductions in construction costs or
hikes in energy costs could make green-roofing feasible over the life-cycle of 40
years.
2) An energy-centric scenario which combines the two most efficient ways in this
study to conserve energy: direct energy conservation and green roofs. This
alternative showed that when green-roofs are integrated in an energy conservation
plan, the construction cost can be recovered in about 18 years and a positive
present worth can be calculated over the life-cycle.
3) A comprehensive approach which combines all the components of sustainable
resource management: decentralized water reclamation facilities, water and
energy conservation, vegetated roofs and alternative energy. This alternative was
also feasible and more suited for citywide management plans.
4) A water-centric alternative which revolves around water conservation,
reclamation and reuse. When combined with green roofs for stormwater retention,
this alternative proved highly unfeasible due to increased initial costs and
insufficient yearly savings. Without green-roofs, this alternative was more
numerically feasible, notably for small ecoblocks, but still had negative present
values. Therefore this alternative would probably work best in communitywide
management plans, or medium to large housing projects. It could also be
5) A conservation-centric approach or a no-green roofs approach that shuns the high
construction cost of green-roofs. Combining both water and energy conservation,
this was the most profitable alternative and can be applied to all types of
development or ecoblocks with varied land use covers. It is however strongly
80
contingent upon regulations and policies soliciting conversation of energy and
water and/or active stakeholder participation.
Figures 7.2 and 7.3 plot the results of the LCCA for the considered alternatives.
-100,000,000
0
100,000,000
200,000,000
300,000,000
400,000,000
500,000,000
600,000,000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Ecoblock
NPW
($)
Green-Roof-CentricEnergy-CentricComprehensiveWater-CentricConservation-Centric
Figure 7.2: NPW of the Five Scenarios in the Ecobloks
0
5
10
15
20
25
30
35
40
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21Ecoblock
Payb
ack
Peri
od (y
ears
)
Energy-CentricComprehensiveConservation-Centric
Figure 7.3: Payback Period of the Three Feasible Scenarios in the Ecoblocks
81
Figure 7.2 shows greater benefits for larger ecoblocks with energy-centric, conservation-
centric and comprehensive approaches and less losses for smaller ecoblocks with green-
roof and water-centric approaches. Also, the two figures suggest that a
conservation/reclamation/reuse approach is the most profitable and the best in paying for
itself [Note that this scenario doesn’t take into account the cost of initiating a
conservation policy or program]. But what figures 7.2 and 7.3 fail to show is the effect of
the properties of each ecoblock on the results. Basically, the NPWs and the PBPs are
influenced by:
- the land use cover which affects the water consumption and conservation as well
as the presence of a sufficient building footprint area, a necessary matrix for green
roofs and their energy and water related benefits.
- the population density in the ecoblock which affects the water supply
requirements, the initial and operational costs of the water reclamation facility and
the benefits from water conservation.
Those two factors can act concordantly in that a high developed land covers (residential,
commercial, industrial) yields both a larger population and more surfaces for green roofs
and as such favors an alternative which integrates green roofs, conservation and water
reclamation. But the two factors can act discordantly in that a larger population density
may not directly result in a larger developed surface or larger green roof surface (e.g.
high rise buildings, tower housing, …) and in that case the benefits from conservation
might outweigh those from green roofs and an alternative that is centered on conservation
would become more profitable. Moreover, a large developed land cover results in a
reduced cover for open urban space such as parks and green corridors, a necessary
82
requirement for low impact development. As well, a larger population density causes
higher operational costs within the ecoblock. In order to better understand those
relationships, the NPWs and PBPs were plotted against the %Developed and the
population density in the ecoblocks. Those plots are shown in figures 7.4 to 7.7 for the
alternatives that proved to be feasible.
0
100,000,000
200,000,000
300,000,000
400,000,000
500,000,000
600,000,000
20 30 40 50 60 70 80 90 100% Developed
NPW
($)
Energy-CentricComprehensiveConservation-Centric
Figure 7.4: NPW versus % Developed
0
5
10
15
20
25
30
35
40
20 30 40 50 60 70 80 90 100% Developed
Payb
ack
Peri
od (y
ears
)
Energy-CentricComprehensiveConservation-CentricLinear (Energy-Centric)Linear (Comprehensive)Linear (Conservation-Centric)
Figure 7.5: PBP versus % Developed
83
0
100,000,000
200,000,000
300,000,000
400,000,000
500,000,000
600,000,000
1,000 3,000 5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000Population Density (persons/km2)
NPW
($)
Energy-CentricComprehensiveConservation-Centric
Figure 7.6: NPW versus Population Density
0
5
10
15
20
25
30
35
40
1,000 3,000 5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000Population Density (persons/km2)
Payb
ack
Peri
od (y
ears
)
Energy-CentricComprehensiveConservation-CentricLinear (Energy-Centric)Linear (Comprehensive)Linear (Conservation-Centric)
Figure 7.7: PBP versus Population Density
The effect of the percentage of developed land cover may be observed in figure 7.4 as the
NPW is highest in the range of 55 to 70%. This implies that there is enough matrix for
vegetated roofs to generate benefits while leaving a percentage for open space and
transportation related land uses. This also signifies the presence of enough people with
whom conservation can produce sufficient savings. For a percentage exceeding 70%, the
84
NPW drops as the installation cost for green roofs and the operational expenses of the
WRF possibly become significant. These effects, however, are not observed with the
payback period as trendlines added to the data showed that there’s hardly any variation
with the developed land cover except for a slight decline along the trendline for the
energy-centric alternative due to increased costs for green roofs for highly developed
ecoblocks.
On the other hand, the effect of the population density is less observed with the values
obtained with the clustering in chapter 2. Most of the values were in the range of 6000-
9000 people/km2 and as such the data in figures 7.6 and 7.7 may not be conclusive.
Nevertheless, one can still make the observation that relatively low NPWs exist at the
ends of the range of population densities. Also the presence of a large number of points
with high NPWs in the 6000-9000 people/km2 range may suggest that with more proper
clustering, points should line up in a curve resembling the normal distribution. Since low
densities create a reduced potential for savings from conservation and high densities
would contribute to high installation and operation costs for alternative energy, water
reclamation and vegetated roofs, median population densities would probably be the best
bet for developments adhering to principles of sustainable management. Another possible
noteworthy observation is that for the densities with the best NPWs in figure 7.6, the
points for comprehensive and conservation-centric alternatives tend to breakaway from
the points of the energy-centric approach. Since the difference is mainly due to
reclamation, conservation and reuse, all of which are contingent upon an adequate
population presence, it can be referred that at least these points are in deed in an
appropriate range of population density. As for the payback period, there is little
85
observed effect with comprehensive and conservation-centric alternatives but better
payback with higher densities for energy-centric approaches. The reason could be that the
energy-centric scenario in this study does not have any operational costs and as such
higher population does not directly translate into higher operational costs.
86
CHAPTER 8
CONCLUSIONS AND FINAL THOUGHTS
This study was mainly concerned with investigating the feasibility of sustainable
development in urban environments, implemented through an integrated resource plan
including water and energy conservation, vegetated roofs for stormwater retention and
building insulation, decentralized water management using water reclamation facilities in
semiautonomous clusters, and further resource management by heat extraction from
wastewater. Water and energy conservation were thoroughly dealt with and broken down
to direct and indirect ways to conserve, while proposing changes or items with no or
minimal additional cost. Green roofs were studied from the perspectives of water
retention, runoff reduction and building insulation. It was deduced, in a separate analysis,
that vegetated roofs are highly effective in reducing runoff from the one-year storm.
However, for larger design storms there’s a need to couple green roofs with other tools
that reduce directly connected impervious areas. For water reclamation, facilities using
biological nutrient removal and yielding a high quality reusable effluent were proposed
inside the urban ecoblocks with their cost estimated from construction curves. Land use
affected the computation of water supply, the size of the reclamation facility and the
potential for water conservation. Integrated resource management which aims at using
waste as a resource for energy as well as reducing the waste stream, was also considered.
Hence, anaerobic digestion and biogas production, along with heat extraction were
studied. TBL and LCC assessments put together the building blocks of the management
plans into coherent approaches. The TBL assessment was used to evaluate the proposed
87
plan by listing how it contributes to enhancing the social, environmental and economic
aspects of the community.
The TBL assessment revealed that the amount of water retained by green roofs exceeds
the amount of water conserved by efficient indoor appliances, and that about 95% of the
savings are energy related. This means that the potential to conserve energy is greater
than that of water, a stipulation that is propped up by the fact that LEED points in the
LEED rating system mostly deal with energy conservation rather than water. Also, since
savings from indirect conservation (resulting from water) were far less than those from
direct energy conservation, a policy that conserves energy strictly by conserving water
would fall short in terms of benefits in spite of the tight water-energy relationship
described by the “Water-Energy Nexus”.
Moreover, within the framework of LEED (Leadership in Energy and Environmental
Design), mandatory statutory constraints stemming from the TBL criteria have been
incorporated therein (Novotny, 2007). For example, US Green Building Council requires
30% indoor and 50% outdoor water savings, as well as stormwater controls, reclaimed
water use, and innovative approaches to treatment. With proper application of the
proposed practices and policies, sustainable management could earn a developer 14
energy efficiency points out of 17 (optimized energy performance, on-site renewable
energy and green power), 3 water efficiency points out of 5 (water efficient landscaping
and water use reduction) and some points for site development and stormwater control, in
the ratings for new building construction (i.e. about 20 points out 69 possible points).
However, in LEED ratings for new neighborhood developments, water and energy
efficiency with stormwater control, reclamation and reuse can only earn 10-12 points out
88
of 106 possible points, as most ratings for neighborhood developments revolve around
accessibility, location, affordability and ecological preservation. Therefore, sustainable
management is not well incorporated into LEED for neighborhood development, even
though it’s a paradigm that is targeted more for general urban planning rather than
specific buildings. Furthermore, another concern with the LEED standards is that they
don’t reflect the amount of improvement in environmental performance, neither the cost
associated with each credit. For example, developers can earn the same number of points
for a bicycle storage room and a 20% reduction in water use, or even a mere 5% in
materials use. Therefore, despite having some TBL criteria interspersed in the LEED
ratings, a TBL assessment (with LCCA) remains a more suited approach to determine the
extent to which a certain development or trend of development would play a part in a
sustainable water and energy management.
The relationship between water and energy also affects the way to configure them in one
policy. LCCA proved that an energy-centric approach that serves the purpose of energy
conservation and optimization is economically viable for both neighborhood size projects
and citywide projects whereas a water-centric approach does not generate enough
benefits to be adopted as a paradigm for large scale urban developments. This approach
may work for neighborhood, housing or community scale projects where cost of water
reclamation will be reduced. Thus, the LLCA suggest that the water-energy nexus is not
marked by equivalence, and is rather unidirectional. Energy-centric policies may not be
contingent upon efficient water management, but a water-centric policy needs a certain
element of energy efficiency to render it economically feasible. This stipulation,
however, may not be applicable in regions suffering from water shortage such as the
89
Southwest of the United States, the Arab Peninsula and Australia. Relative water
abundance in the Northeast states, results in relatively lower costs for water treatment and
reclamation, but high costs in water-shorted entities - due to costly treatments such as
reverse osmosis for seawater desalination and ultrafiltration - could mean that water
conservation benefits are much greater and a water centric approach might work. The
added energy requirements of advanced treatment may also impart the water-energy
nexus with more equivalence.
Conceivably, the water-energy relationship wouldn’t be of greater significance when both
resources are combined into one policy. The LCCA proved that a comprehensive
alternative integrating all of the components in this study and a conservation-centric
approach are the most economically viable and suitable for all sizes of ecoblocks. This
directly relates to the fact that the best strategy for sustainable and resilient urban
watersheds is a holistic paradigm that congregates and optimizes interdependent elements
into a well-targeted policy (Novotny, 2007). Conversely, a strategy concerned with a
“part” rather than the “whole” wouldn’t be as effective, as shown by a green-roof-centric
alternative which focuses only on the benefits of green-roofs. Such an alternative did not
generate enough benefits to recover the cost of green roofs over their life-cycle and
needed reduced construction costs or increased energy prices (both of which might not be
implausible) in order to become feasible.
Factors that affect the choice of an alternative as well as its efficacy are the size of the
target area or the ecoblock, the land use within the ecoblock and the population density.
This study established with a good level of confidence that sustainable management is
feasible but to a lesser level of certainty the most adequate properties of an ecoblock.
90
While the payback period was less dependent on the developed land cover and the
population density, the NPW showed high values at 55-70% developed land and a
population density in the range of 6000-9000 persons/km2. A minimum %development
that ensures the presence of enough roof surfaces and a minimum population density that
ensures enough potential for savings from conservation and reuse are needed. Large
densities and roof surfaces may contribute to high operational costs for heat extraction
and water reclamation and a reduced land cover for green ecotones and open spaces
which inflicts on the environment and the quality of life. As with any feasibility study,
the figure and conclusions are not definitive. Sources of potential errors and uncertainties
in this study include and may not be limited to:
- Avoided costs or costs that would have been spent were it for the proposed management
plan. Examples include the cost of urban BMPs (e.g. ponds) that would produce the same
reductions in urban runoff as green roofs, the cost of water that is used to replenish the
groundwater table and prevent subsidence, as well the cost associated with reducing the
GHG levels. Avoided costs constitute unqualified economic benefits.
- Unquantified costs or costs that were not included due to difficulties in doing so or lack
of data. For instance, sludge handling at the cluster WRFs may still be centralized at a
specific facility and could necessitate an additional cost that accounts for transport of
sludge to the treatment location.
- The clustering itself. A city can be clustered in an infinite number of ways and some
clustering methods could be more efficient than others. Future research studies may focus
on the clustering; possibly through an advanced GIS model that incorporates this
91
methodology and studies the variability of the results with different layouts of the
ecoblocks.
- Uncertainties with the distribution of the heat extraction system. Heat extraction is a
relatively new technology and as such it would be challenging to get exact estimates of
the installation and maintenance costs of a heat extraction system. These numbers may
vary between regions and states, and also depend on the heat extraction network itself.
This study assumes centralized heat extraction at the WRF where the heat is used
proximately or locally within the facility (e.g. to heat the digesters). However, the
Rabtherm system can be installed in a decentralized manner such as at every large
commercial building where the heat is used within the corresponding relevant building.
Such a scenario would have a different cost for IRM in the ecoblocks.
Further research might also quantify - for a specific management plan - with
mathematical formulas and models the relationships between the NPW or PBP and the
population density, the %green, the %developed and the size of the ecoblock, possibly
using data from different cities. The methodology used in this study for Boston, MA is
directly applicable in other cities. Parameters that would need to be changed are the land
use percentages, the costs of treating water and wastewater, the cost of providing energy
and locational multipliers. Other studies could also integrate resource management with
alternative transportation, rapid transit and solar energy. Resource management
assessments can also be performed on a well defined area of development (such a
university campus or a housing project) where other green design elements such as
porous pavement and bioswales can be implemented; conservation can be tailored
92
specifically to the occupancy and land use of the development, and water reclamation and
biogas production can be performed using small decentralized systems.
Another area which can be addressed is the financing of sustainable management and
how it affects the NPWs of the proposed alternatives. This study proved that sustainable
management can pay for itself but there could be additional costs to initiate resource
management programs and policies, and overcome the present barriers to their
implementation. For example, stakeholder participation through conservation may need
awareness programs and enacting new policies that need monitoring and follow up.
Speers (2007) referred to an analysis by Lindblom (1959) when he termed current
decision making a “successive limited comparison” or “muddling-through” since
administrators do not perform a comprehensive study of every option but rather look only
at policies that differ in small degrees with the ones currently in effect. Speers identified
this as a major administrative impediment, while Novotny and Brown (2007) also
warmed that there are significant economic and institutional barriers that need to be
overcome through education, new legislations, stakeholder participation and innovative
financing mechanisms.
93
APPENDIX A
EXTRACTS FROM IPCC REPORT 2007
Figure A.1: Atmospheric
concentrations of carbon dioxide,
methane and nitrous oxide over the last 10,000 years (large panels) and since
1750 (inset panels). (IPCC, 2007)
94
Figure A.2: Observed changes in global average surface temperature, global average sea level rise and Northern Hemisphere snow cover. Smoothed curves represent decadal
averaged values while circles show yearly values and the shaded areas are the uncertainty intervals (IPCC, 2007)
95
APPENDIX B
LAND USE CODE DEFINITIONS
Code Category Definition
1 Cropland Intensive agriculture 2 Pasture Extensive agriculture 3 Forest Forest 4 Wetland Nonforested freshwater wetland 5 Mining Sand; gravel & rock 6 Open Land Abandoned agriculture; power lines; areas of no vegetation
7 Participation Recreation Golf; tennis; Playgrounds; skiing
8 Spectator Recreation Stadiums; racetracks; Fairgrounds; drive-ins
9 Water Based Recreation Beaches; marinas; Swimming pools
10 Residential Multi-family 11 Residential Smaller than 1/4 acre lots 12 Residential 1/4 - 1/2 acre lots 13 Residential Larger than 1/2 acre lots 14 Salt Wetland Salt marsh 15 Commercial General urban; shopping center 16 Industrial Light & heavy industry
17 Urban Open Parks; cemeteries; public & institutional greenspace; also vacant undeveloped land
18 Transportation Airports; docks; divided highway; freight; storage; railroads 19 Waste Disposal Landfills; sewage lagoons 20 Water Fresh water; coastal embayment 21 Woody Perennial Orchard; nursery; cranberry bog 22 No Change Code used by MassGIS only during quality checking
(http://www.mass.gov/mgis/lus.htm)
96
APPENDIX C
DATA ON ENERGY REQUIREMENTS FOR WATER
CONVEYANCE AND TREATMENT
Table C.1: Cumulative Energy use in New England (Wilson, 2008) Treatment Level Cumulative Energy (kWh/MG)
Water Supply and Treatment 1800 + Distribution 2470
+ Preliminary Treatment 3170 + Secondary Treatment 4470
+ Advanced Treatment with Nitrogen Removal 6370 + MBR (to reclaim water and reuse it) 10470
Figure C.1: Energy Usage for Water Treatment and Distribution (AWWA, 1992)
98
APPENDIX D
2005 – 2007 PRECIPITATION SERIES FOR BOSTON WITH
RETAINED DEPTH BY GREEN ROOFS
Date P (in) P (cm) Retained
Depth (cm) Date P (in) P (cm) Retained Depth (cm)
1/1/2005 0 0.0000 0.0000 2/1/2005 0 0.0000 0.00001/2/2005 0.02 0.0508 0.0447 2/2/2005 0 0.0000 0.00001/3/2005 0.18 0.4572 0.4023 2/3/2005 0.23 0.5842 0.51411/4/2005 0.29 0.7366 0.6482 2/4/2005 0.04 0.1016 0.08941/5/2005 0.1 0.2540 0.2235 2/5/2005 0.01 0.0254 0.02241/6/2005 0.64 1.6256 1.4305 2/6/2005 0 0.0000 0.00001/7/2005 0 0.0000 0.0000 2/7/2005 0 0.0000 0.00001/8/2005 0.58 1.4732 1.2964 2/8/2005 0 0.0000 0.00001/9/2005 0 0.0000 0.0000 2/9/2005 0.01 0.0254 0.0224
1/10/2005 0.03 0.0762 0.0671 2/10/2005 0.86 2.1844 1.92231/11/2005 0.01 0.0254 0.0224 2/11/2005 0 0.0000 0.00001/12/2005 0.29 0.7366 0.6482 2/12/2005 0 0.0000 0.00001/13/2005 0.05 0.1270 0.1118 2/13/2005 0 0.0000 0.00001/14/2005 0.44 1.1176 0.9835 2/14/2005 0.03 0.0762 0.06711/15/2005 0.01 0.0254 0.0224 2/15/2005 0.32 0.8128 0.71531/16/2005 0.05 0.1270 0.1118 2/16/2005 0.19 0.4826 0.42471/17/2005 0 0.0000 0.0000 2/17/2005 0 0.0000 0.00001/18/2005 0 0.0000 0.0000 2/18/2005 0 0.0000 0.00001/19/2005 0.07 0.1778 0.1565 2/19/2005 0 0.0000 0.00001/20/2005 0.01 0.0254 0.0224 2/20/2005 0.01 0.0254 0.02241/21/2005 0 0.0000 0.0000 2/21/2005 0.09 0.2286 0.20121/22/2005 0.18 0.4572 0.4023 2/22/2005 0.03 0.0762 0.06711/23/2005 0.26 0.6604 0.5812 2/23/2005 0 0.0000 0.00001/24/2005 0 0.0000 0.0000 2/24/2005 0.11 0.2794 0.24591/25/2005 0 0.0000 0.0000 2/25/2005 0.06 0.1524 0.13411/26/2005 0.2 0.5080 0.4470 2/26/2005 0 0.0000 0.00001/27/2005 0 0.0000 0.0000 2/27/2005 0 0.0000 0.00001/28/2005 0 0.0000 0.0000 2/28/2005 0.17 0.4318 0.38001/29/2005 0 0.0000 0.0000 4/1/2005 0.01 0.0254 0.02241/30/2005 0 0.0000 0.0000 4/2/2005 0.81 2.0574 1.81051/31/2005 0 0.0000 0.0000 4/3/2005 0.44 1.1176 0.98353/1/2005 0.11 0.2794 0.2459 4/4/2005 0 0.0000 0.00003/2/2005 0 0.0000 0.0000 4/5/2005 0 0.0000 0.00003/3/2005 0 0.0000 0.0000 4/6/2005 0 0.0000 0.00003/4/2005 0 0.0000 0.0000 4/7/2005 0.08 0.2032 0.17883/5/2005 0 0.0000 0.0000 4/8/2005 0.21 0.5334 0.46943/6/2005 0 0.0000 0.0000 4/9/2005 0 0.0000 0.00003/7/2005 0 0.0000 0.0000 4/10/2005 0 0.0000 0.00003/8/2005 0.49 1.2446 1.0952 4/11/2005 0 0.0000 0.00003/9/2005 0 0.0000 0.0000 4/12/2005 0.04 0.1016 0.0894
3/10/2005 0.01 0.0254 0.0224 4/13/2005 0 0.0000 0.00003/11/2005 0 0.0000 0.0000 4/14/2005 0 0.0000 0.00003/12/2005 0.8 2.0320 1.7882 4/15/2005 0.01 0.0254 0.02243/13/2005 0 0.0000 0.0000 4/16/2005 0 0.0000 0.00003/14/2005 0 0.0000 0.0000 4/17/2005 0 0.0000 0.00003/15/2005 0 0.0000 0.0000 4/18/2005 0 0.0000 0.00003/16/2005 0 0.0000 0.0000 4/19/2005 0 0.0000 0.00003/17/2005 0 0.0000 0.0000 4/20/2005 0.03 0.0762 0.06713/18/2005 0 0.0000 0.0000 4/21/2005 0.07 0.1778 0.15653/19/2005 0 0.0000 0.0000 4/22/2005 0 0.0000 0.00003/20/2005 0 0.0000 0.0000 4/23/2005 0.49 1.2446 1.09523/21/2005 0 0.0000 0.0000 4/24/2005 0.3 0.7620 0.6706
99
3/22/2005 0 0.0000 0.0000 4/25/2005 0.06 0.1524 0.13413/23/2005 0.04 0.1016 0.0894 4/26/2005 0 0.0000 0.00003/24/2005 0.15 0.3810 0.3353 4/27/2005 0.32 0.8128 0.71533/25/2005 0 0.0000 0.0000 4/28/2005 0 0.0000 0.00003/26/2005 0 0.0000 0.0000 4/29/2005 0 0.0000 0.00003/27/2005 0 0.0000 0.0000 4/30/2005 0.32 0.8128 0.71533/28/2005 1.3 3.3020 1.7831 6/1/2005 0 0.0000 0.00003/29/2005 0.49 1.2446 1.0952 6/2/2005 0 0.0000 0.00003/30/2005 0 0.0000 0.0000 6/3/2005 0 0.0000 0.00003/31/2005 0 0.0000 0.0000 6/4/2005 0 0.0000 0.00005/1/2005 0.1 0.2540 0.2235 6/5/2005 0.14 0.3556 0.31295/2/2005 0.04 0.1016 0.0894 6/6/2005 0.15 0.3810 0.33535/3/2005 0 0.0000 0.0000 6/7/2005 1 2.5400 1.37165/4/2005 0 0.0000 0.0000 6/8/2005 0.58 1.4732 1.29645/5/2005 0 0.0000 0.0000 6/9/2005 0.45 1.1430 1.00585/6/2005 0.04 0.1016 0.0894 6/10/2005 0 0.0000 0.00005/7/2005 0.56 1.4224 1.2517 6/11/2005 0 0.0000 0.00005/8/2005 0.05 0.1270 0.1118 6/12/2005 0 0.0000 0.00005/9/2005 0 0.0000 0.0000 6/13/2005 0 0.0000 0.0000
5/10/2005 0 0.0000 0.0000 6/14/2005 0 0.0000 0.00005/11/2005 0 0.0000 0.0000 6/15/2005 0.06 0.1524 0.13415/12/2005 0 0.0000 0.0000 6/16/2005 0.13 0.3302 0.29065/13/2005 0 0.0000 0.0000 6/17/2005 0.01 0.0254 0.02245/14/2005 0 0.0000 0.0000 6/18/2005 0 0.0000 0.00005/15/2005 0.01 0.0254 0.0224 6/19/2005 0.05 0.1270 0.11185/16/2005 0.27 0.6858 0.6035 6/20/2005 0 0.0000 0.00005/17/2005 0 0.0000 0.0000 6/21/2005 0 0.0000 0.00005/18/2005 0.04 0.1016 0.0894 6/22/2005 0.03 0.0762 0.06715/19/2005 0.01 0.0254 0.0224 6/23/2005 0 0.0000 0.00005/20/2005 0 0.0000 0.0000 6/24/2005 0.02 0.0508 0.04475/21/2005 0.23 0.5842 0.5141 6/25/2005 0 0.0000 0.00005/22/2005 0.03 0.0762 0.0671 6/26/2005 0.2 0.5080 0.44705/23/2005 0.06 0.1524 0.1341 6/27/2005 0 0.0000 0.00005/24/2005 0.92 2.3368 2.0564 6/28/2005 0 0.0000 0.00005/25/2005 0.74 1.8796 1.6540 6/29/2005 0 0.0000 0.00005/26/2005 0.54 1.3716 1.2070 6/30/2005 0 0.0000 0.00005/27/2005 0 0.0000 0.0000 8/1/2005 0.56 1.4224 1.25175/28/2005 0.16 0.4064 0.3576 8/2/2005 0.01 0.0254 0.02245/29/2005 0.13 0.3302 0.2906 8/3/2005 0 0.0000 0.00005/30/2005 0.04 0.1016 0.0894 8/4/2005 0 0.0000 0.00005/31/2005 0.01 0.0254 0.0224 8/5/2005 0.55 1.3970 1.22947/1/2005 0 0.0000 0.0000 8/6/2005 0 0.0000 0.00007/2/2005 0 0.0000 0.0000 8/7/2005 0 0.0000 0.00007/3/2005 0 0.0000 0.0000 8/8/2005 0 0.0000 0.00007/4/2005 0 0.0000 0.0000 8/9/2005 0.02 0.0508 0.04477/5/2005 0 0.0000 0.0000 8/10/2005 0 0.0000 0.00007/6/2005 2.04 5.1816 2.7981 8/11/2005 0.23 0.5842 0.51417/7/2005 0 0.0000 0.0000 8/12/2005 0 0.0000 0.00007/8/2005 0.95 2.4130 2.1234 8/13/2005 0.07 0.1778 0.15657/9/2005 0.2 0.5080 0.4470 8/14/2005 0.6 1.5240 1.3411
7/10/2005 0 0.0000 0.0000 8/15/2005 0.13 0.3302 0.29067/11/2005 0 0.0000 0.0000 8/16/2005 0 0.0000 0.00007/12/2005 0 0.0000 0.0000 8/17/2005 0 0.0000 0.00007/13/2005 0 0.0000 0.0000 8/18/2005 0 0.0000 0.00007/14/2005 0 0.0000 0.0000 8/19/2005 0 0.0000 0.00007/15/2005 0 0.0000 0.0000 8/20/2005 0 0.0000 0.00007/16/2005 0 0.0000 0.0000 8/21/2005 0.02 0.0508 0.04477/17/2005 0 0.0000 0.0000 8/22/2005 0 0.0000 0.00007/18/2005 0.03 0.0762 0.0671 8/23/2005 0 0.0000 0.00007/19/2005 0 0.0000 0.0000 8/24/2005 0 0.0000 0.00007/20/2005 0 0.0000 0.0000 8/25/2005 0 0.0000 0.00007/21/2005 0 0.0000 0.0000 8/26/2005 0 0.0000 0.00007/22/2005 0.15 0.3810 0.3353 8/27/2005 0 0.0000 0.00007/23/2005 0 0.0000 0.0000 8/28/2005 0 0.0000 0.00007/24/2005 0 0.0000 0.0000 8/29/2005 0.33 0.8382 0.73767/25/2005 0 0.0000 0.0000 8/30/2005 0.33 0.8382 0.73767/26/2005 0 0.0000 0.0000 8/31/2005 0.03 0.0762 0.06717/27/2005 0 0.0000 0.0000 10/1/2005 0 0.0000 0.00007/28/2005 0 0.0000 0.0000 10/2/2005 0 0.0000 0.0000
100
7/29/2005 0 0.0000 0.0000 10/3/2005 0 0.0000 0.00007/30/2005 0 0.0000 0.0000 10/4/2005 0 0.0000 0.00007/31/2005 0 0.0000 0.0000 10/5/2005 0 0.0000 0.00009/1/2005 0.19 0.4826 0.4247 10/6/2005 0 0.0000 0.00009/2/2005 0 0.0000 0.0000 10/7/2005 0.03 0.0762 0.06719/3/2005 0 0.0000 0.0000 10/8/2005 1.02 2.5908 1.39909/4/2005 0 0.0000 0.0000 10/9/2005 0.92 2.3368 2.05649/5/2005 0 0.0000 0.0000 10/10/2005 0.09 0.2286 0.20129/6/2005 0 0.0000 0.0000 10/11/2005 0.22 0.5588 0.49179/7/2005 0 0.0000 0.0000 10/12/2005 0.02 0.0508 0.04479/8/2005 0 0.0000 0.0000 10/13/2005 0.06 0.1524 0.13419/9/2005 0 0.0000 0.0000 10/14/2005 1.22 xxx xxx
9/10/2005 0 0.0000 0.0000 10/15/2005 2.89 10.4400 5.01129/11/2005 0 0.0000 0.0000 10/16/2005 0 0.0000 0.00009/12/2005 0 0.0000 0.0000 10/17/2005 0 0.0000 0.00009/13/2005 0 0.0000 0.0000 10/18/2005 0.02 0.0508 0.04479/14/2005 0 0.0000 0.0000 10/19/2005 0 0.0000 0.00009/15/2005 0.98 2.4892 2.1905 10/20/2005 0 0.0000 0.00009/16/2005 0.12 0.3048 0.2682 10/21/2005 0 0.0000 0.00009/17/2005 0.01 0.0254 0.0224 10/22/2005 0.64 1.6256 1.43059/18/2005 0 0.0000 0.0000 10/23/2005 0.46 1.1684 1.02829/19/2005 0 0.0000 0.0000 10/24/2005 0.11 0.2794 0.24599/20/2005 0.01 0.0254 0.0224 10/25/2005 1.26 3.2004 1.72829/21/2005 0 0.0000 0.0000 10/26/2005 0 0.0000 0.00009/22/2005 0 0.0000 0.0000 10/27/2005 0 0.0000 0.00009/23/2005 0 0.0000 0.0000 10/28/2005 0 0.0000 0.00009/24/2005 0 0.0000 0.0000 10/29/2005 0.45 1.1430 1.00589/25/2005 0 0.0000 0.0000 10/30/2005 0 0.0000 0.00009/26/2005 0.22 0.5588 0.4917 10/31/2005 0 0.0000 0.00009/27/2005 0.02 0.0508 0.0447 12/1/2005 0 0.0000 0.00009/28/2005 0 0.0000 0.0000 12/2/2005 0 0.0000 0.00009/29/2005 0.24 0.6096 0.5364 12/3/2005 0 0.0000 0.00009/30/2005 0 0.0000 0.0000 12/4/2005 0.12 0.3048 0.268211/1/2005 0 0.0000 0.0000 12/5/2005 0 0.0000 0.000011/2/2005 0 0.0000 0.0000 12/6/2005 0 0.0000 0.000011/3/2005 0 0.0000 0.0000 12/7/2005 0 0.0000 0.000011/4/2005 0 0.0000 0.0000 12/8/2005 0 0.0000 0.000011/5/2005 0 0.0000 0.0000 12/9/2005 0.63 1.6002 1.408211/6/2005 0.22 0.5588 0.4917 12/10/2005 0 0.0000 0.000011/7/2005 0.01 0.0254 0.0224 12/11/2005 0 0.0000 0.000011/8/2005 0 0.0000 0.0000 12/12/2005 0 0.0000 0.000011/9/2005 0.22 0.5588 0.4917 12/13/2005 0 0.0000 0.000011/10/2005 0.36 0.9144 0.8047 12/14/2005 0 0.0000 0.000011/11/2005 0.01 0.0254 0.0224 12/15/2005 0 0.0000 0.000011/12/2005 0.03 0.0762 0.0671 12/16/2005 0.64 1.6256 1.430511/13/2005 0 0.0000 0.0000 12/17/2005 0 0.0000 0.000011/14/2005 0 0.0000 0.0000 12/18/2005 0 0.0000 0.000011/15/2005 0.1 0.2540 0.2235 12/19/2005 0 0.0000 0.000011/16/2005 0.21 0.5334 0.4694 12/20/2005 0 0.0000 0.000011/17/2005 0.15 0.3810 0.3353 12/21/2005 0 0.0000 0.000011/18/2005 0 0.0000 0.0000 12/22/2005 0 0.0000 0.000011/19/2005 0 0.0000 0.0000 12/23/2005 0 0.0000 0.000011/20/2005 0 0.0000 0.0000 12/24/2005 0 0.0000 0.000011/21/2005 0.16 0.4064 0.3576 12/25/2005 0.21 0.5334 0.469411/22/2005 1.61 4.0894 2.2083 12/26/2005 0.77 1.9558 1.721111/23/2005 0.02 0.0508 0.0447 12/27/2005 0 0.0000 0.000011/24/2005 0.03 0.0762 0.0671 12/28/2005 0 0.0000 0.000011/25/2005 0 0.0000 0.0000 12/29/2005 0.24 0.6096 0.536411/26/2005 0 0.0000 0.0000 12/30/2005 0 0.0000 0.000011/27/2005 0 0.0000 0.0000 12/31/2005 0.05 0.1270 0.111811/28/2005 0 0.0000 0.000011/29/2005 0 0.0000 0.000011/30/2005 0.64 1.6256 1.4305
1/1/2006 0 0.0000 0.0000 2/1/2006 0 0.0000 0.00001/2/2006 0.02 0.0508 0.0447 2/2/2006 0 0.0000 0.00001/3/2006 0.18 0.4572 0.4023 2/3/2006 0.61 1.5494 1.36351/4/2006 0.29 0.7366 0.6482 2/4/2006 0.45 1.1430 1.00581/5/2006 0.1 0.2540 0.2235 2/5/2006 0.34 0.8636 0.7600
101
1/6/2006 0.64 1.6256 1.4305 2/6/2006 0 0.0000 0.00001/7/2006 0 0.0000 0.0000 2/7/2006 0 0.0000 0.00001/8/2006 0.58 1.4732 1.2964 2/8/2006 0 0.0000 0.00001/9/2006 0 0.0000 0.0000 2/9/2006 0 0.0000 0.0000
1/10/2006 0.03 0.0762 0.0671 2/10/2006 0 0.0000 0.00001/11/2006 0.01 0.0254 0.0224 2/11/2006 0 0.0000 0.00001/12/2006 0.29 0.7366 0.6482 2/12/2006 0.17 0.4318 0.38001/13/2006 0.05 0.1270 0.1118 2/13/2006 0 0.0000 0.00001/14/2006 0.44 1.1176 0.9835 2/14/2006 0 0.0000 0.00001/15/2006 0.01 0.0254 0.0224 2/15/2006 0 0.0000 0.00001/16/2006 0.05 0.1270 0.1118 2/16/2006 0 0.0000 0.00001/17/2006 0 0.0000 0.0000 2/17/2006 0.08 0.2032 0.17881/18/2006 0 0.0000 0.0000 2/18/2006 0 0.0000 0.00001/19/2006 0.07 0.1778 0.1565 2/19/2006 0 0.0000 0.00001/20/2006 0.01 0.0254 0.0224 2/20/2006 0 0.0000 0.00001/21/2006 0 0.0000 0.0000 2/21/2006 0 0.0000 0.00001/22/2006 0.18 0.4572 0.4023 2/22/2006 0 0.0000 0.00001/23/2006 0.26 0.6604 0.5812 2/23/2006 0.05 0.1270 0.11181/24/2006 0 0.0000 0.0000 2/24/2006 0 0.0000 0.00001/25/2006 0 0.0000 0.0000 2/25/2006 0.02 0.0508 0.04471/26/2006 0.2 0.5080 0.4470 2/26/2006 0 0.0000 0.00001/27/2006 0 0.0000 0.0000 2/27/2006 0 0.0000 0.00001/28/2006 0 0.0000 0.0000 2/28/2006 0.01 0.0254 0.02241/29/2006 0 0.0000 0.0000 4/1/2006 0.06 0.1524 0.13411/30/2006 0 0.0000 0.0000 4/2/2006 0 0.0000 0.00001/31/2006 0 0.0000 0.0000 4/3/2006 0.05 0.1270 0.11183/1/2006 0 0.0000 0.0000 4/4/2006 0.36 0.9144 0.80473/2/2006 0 0.0000 0.0000 4/5/2006 0.2 0.5080 0.44703/3/2006 0 0.0000 0.0000 4/6/2006 0 0.0000 0.00003/4/2006 0 0.0000 0.0000 4/7/2006 0.11 0.2794 0.24593/5/2006 0 0.0000 0.0000 4/8/2006 0.12 0.3048 0.26823/6/2006 0 0.0000 0.0000 4/9/2006 0 0.0000 0.00003/7/2006 0 0.0000 0.0000 4/10/2006 0 0.0000 0.00003/8/2006 0 0.0000 0.0000 4/11/2006 0 0.0000 0.00003/9/2006 0 0.0000 0.0000 4/12/2006 0 0.0000 0.0000
3/10/2006 0 0.0000 0.0000 4/13/2006 0.01 0.0254 0.02243/11/2006 0 0.0000 0.0000 4/14/2006 0.03 0.0762 0.06713/12/2006 0 0.0000 0.0000 4/15/2006 0 0.0000 0.00003/13/2006 0.3 0.7620 0.6706 4/16/2006 0 0.0000 0.00003/14/2006 0.25 0.6350 0.5588 4/17/2006 0.01 0.0254 0.02243/15/2006 0 0.0000 0.0000 4/18/2006 0.01 0.0254 0.02243/16/2006 0 0.0000 0.0000 4/19/2006 0 0.0000 0.00003/17/2006 0 0.0000 0.0000 4/20/2006 0 0.0000 0.00003/18/2006 0 0.0000 0.0000 4/21/2006 0 0.0000 0.00003/19/2006 0 0.0000 0.0000 4/22/2006 0.11 0.2794 0.24593/20/2006 0 0.0000 0.0000 4/23/2006 0.61 1.5494 1.36353/21/2006 0 0.0000 0.0000 4/24/2006 0.13 0.3302 0.29063/22/2006 0 0.0000 0.0000 4/25/2006 0.02 0.0508 0.04473/23/2006 0 0.0000 0.0000 4/26/2006 0 0.0000 0.00003/24/2006 0 0.0000 0.0000 4/27/2006 0 0.0000 0.00003/25/2006 0.01 0.0254 0.0224 4/28/2006 0 0.0000 0.00003/26/2006 0 0.0000 0.0000 4/29/2006 0 0.0000 0.00003/27/2006 0 0.0000 0.0000 4/30/2006 0 0.0000 0.00003/28/2006 0 0.0000 0.0000 6/1/2006 0.14 0.3556 0.31293/29/2006 0 0.0000 0.0000 6/2/2006 0.53 1.3462 1.18473/30/2006 0 0.0000 0.0000 6/3/2006 1.91 4.8514 2.61983/31/2006 0 0.0000 0.0000 6/4/2006 0.3 0.7620 0.67065/1/2006 0.01 0.0254 0.0224 6/5/2006 0 0.0000 0.00005/2/2006 0.91 2.3114 2.0340 6/6/2006 0 0.0000 0.00005/3/2006 0.26 0.6604 0.5812 6/7/2006 2.89 7.3406 3.96395/4/2006 0 0.0000 0.0000 6/8/2006 0.2 0.5080 0.44705/5/2006 0 0.0000 0.0000 6/9/2006 0.06 0.1524 0.13415/6/2006 0 0.0000 0.0000 6/10/2006 0.43 1.0922 0.96115/7/2006 0 0.0000 0.0000 6/11/2006 0 0.0000 0.00005/8/2006 0 0.0000 0.0000 6/12/2006 0 0.0000 0.00005/9/2006 0.96 2.4384 2.1458 6/13/2006 0 0.0000 0.0000
5/10/2006 0.55 1.3970 1.2294 6/14/2006 0 0.0000 0.00005/11/2006 0.08 0.2032 0.1788 6/15/2006 0.1 0.2540 0.22355/12/2006 0.37 0.9398 0.8270 6/16/2006 0 0.0000 0.0000
102
5/13/2006 3.84 xxx xxx 6/17/2006 0 0.0000 0.00005/14/2006 3.77 19.3300 9.2784 6/18/2006 0 0.0000 0.00005/15/2006 0.36 0.9144 0.8047 6/19/2006 0 0.0000 0.00005/16/2006 0.52 1.3208 1.1623 6/20/2006 0.37 0.9398 0.82705/17/2006 0 0.0000 0.0000 6/21/2006 0 0.0000 0.00005/18/2006 0 0.0000 0.0000 6/22/2006 0 0.0000 0.00005/19/2006 0.47 1.1938 1.0505 6/23/2006 1.36 3.4544 1.86545/20/2006 0 0.0000 0.0000 6/24/2006 0.69 1.7526 1.54235/21/2006 0.11 0.2794 0.2459 6/25/2006 0.95 2.4130 2.12345/22/2006 0 0.0000 0.0000 6/26/2006 0 0.0000 0.00005/23/2006 0 0.0000 0.0000 6/27/2006 0 0.0000 0.00005/24/2006 0 0.0000 0.0000 6/28/2006 0.05 0.1270 0.11185/25/2006 0 0.0000 0.0000 6/29/2006 0 0.0000 0.00005/26/2006 0.27 0.6858 0.6035 6/30/2006 0.13 0.3302 0.29065/27/2006 0 0.0000 0.0000 8/1/2006 0.02 0.0508 0.04475/28/2006 0 0.0000 0.0000 8/2/2006 0 0.0000 0.00005/29/2006 0 0.0000 0.0000 8/3/2006 0 0.0000 0.00005/30/2006 0 0.0000 0.0000 8/4/2006 0.31 0.7874 0.69295/31/2006 0 0.0000 0.0000 8/5/2006 0 0.0000 0.00007/1/2006 0 0.0000 0.0000 8/6/2006 0 0.0000 0.00007/2/2006 0 0.0000 0.0000 8/7/2006 0.04 0.1016 0.08947/3/2006 0 0.0000 0.0000 8/8/2006 0 0.0000 0.00007/4/2006 0 0.0000 0.0000 8/9/2006 0 0.0000 0.00007/5/2006 0 0.0000 0.0000 8/10/2006 0 0.0000 0.00007/6/2006 0.15 0.3810 0.3353 8/11/2006 0 0.0000 0.00007/7/2006 0 0.0000 0.0000 8/12/2006 0 0.0000 0.00007/8/2006 0 0.0000 0.0000 8/13/2006 0 0.0000 0.00007/9/2006 0 0.0000 0.0000 8/14/2006 0 0.0000 0.0000
7/10/2006 0 0.0000 0.0000 8/15/2006 0.53 1.3462 1.18477/11/2006 0.02 0.0508 0.0447 8/16/2006 0 0.0000 0.00007/12/2006 1.02 2.5908 1.3990 8/17/2006 0 0.0000 0.00007/13/2006 0.17 0.4318 0.3800 8/18/2006 0 0.0000 0.00007/14/2006 0 0.0000 0.0000 8/19/2006 0 0.0000 0.00007/15/2006 0 0.0000 0.0000 8/20/2006 0.8 2.0320 1.78827/16/2006 0 0.0000 0.0000 8/21/2006 0 0.0000 0.00007/17/2006 0 0.0000 0.0000 8/22/2006 0 0.0000 0.00007/18/2006 0.22 0.5588 0.4917 8/23/2006 0 0.0000 0.00007/19/2006 0.19 0.4826 0.4247 8/24/2006 0.01 0.0254 0.02247/20/2006 0 0.0000 0.0000 8/25/2006 0.84 2.1336 1.87767/21/2006 1.29 3.2766 1.7694 8/26/2006 0 0.0000 0.00007/22/2006 0.12 0.3048 0.2682 8/27/2006 0.4 1.0160 0.89417/23/2006 0.11 0.2794 0.2459 8/28/2006 0.11 0.2794 0.24597/24/2006 0 0.0000 0.0000 8/29/2006 0.14 0.3556 0.31297/25/2006 0 0.0000 0.0000 8/30/2006 0 0.0000 0.00007/26/2006 0 0.0000 0.0000 8/31/2006 0 0.0000 0.00007/27/2006 0 0.0000 0.0000 10/1/2006 0.38 0.9652 0.84947/28/2006 0.29 0.7366 0.6482 10/2/2006 0 0.0000 0.00007/29/2006 0 0.0000 0.0000 10/3/2006 0 0.0000 0.00007/30/2006 0 0.0000 0.0000 10/4/2006 0 0.0000 0.00007/31/2006 0 0.0000 0.0000 10/5/2006 0.12 0.3048 0.26829/1/2006 0 0.0000 0.0000 10/6/2006 0 0.0000 0.00009/2/2006 0 0.0000 0.0000 10/7/2006 0 0.0000 0.00009/3/2006 0.25 0.6350 0.5588 10/8/2006 0 0.0000 0.00009/4/2006 0 0.0000 0.0000 10/9/2006 0 0.0000 0.00009/5/2006 0.07 0.1778 0.1565 10/10/2006 0 0.0000 0.00009/6/2006 0.01 0.0254 0.0224 10/11/2006 0.85 2.1590 1.89999/7/2006 0 0.0000 0.0000 10/12/2006 0.39 0.9906 0.87179/8/2006 0 0.0000 0.0000 10/13/2006 0 0.0000 0.00009/9/2006 0.22 0.5588 0.4917 10/14/2006 0 0.0000 0.0000
9/10/2006 0 0.0000 0.0000 10/15/2006 0 0.0000 0.00009/11/2006 0 0.0000 0.0000 10/16/2006 0 0.0000 0.00009/12/2006 0 0.0000 0.0000 10/17/2006 0.13 0.3302 0.29069/13/2006 0 0.0000 0.0000 10/18/2006 0 0.0000 0.00009/14/2006 0.3 0.7620 0.6706 10/19/2006 0 0.0000 0.00009/15/2006 0 0.0000 0.0000 10/20/2006 0.4 1.0160 0.89419/16/2006 0 0.0000 0.0000 10/21/2006 0 0.0000 0.00009/17/2006 0 0.0000 0.0000 10/22/2006 0 0.0000 0.00009/18/2006 0 0.0000 0.0000 10/23/2006 0.21 0.5334 0.46949/19/2006 0.5 1.2700 1.1176 10/24/2006 0 0.0000 0.0000
103
9/20/2006 0.07 0.1778 0.1565 10/25/2006 0 0.0000 0.00009/21/2006 0 0.0000 0.0000 10/26/2006 0 0.0000 0.00009/22/2006 0 0.0000 0.0000 10/27/2006 0 0.0000 0.00009/23/2006 0.04 0.1016 0.0894 10/28/2006 2.02 5.1308 2.77069/24/2006 0 0.0000 0.0000 10/29/2006 0 0.0000 0.00009/25/2006 0 0.0000 0.0000 10/30/2006 0 0.0000 0.00009/26/2006 0 0.0000 0.0000 10/31/2006 0 0.0000 0.00009/27/2006 0 0.0000 0.0000 12/1/2006 0.18 0.4572 0.40239/28/2006 0 0.0000 0.0000 12/2/2006 0 0.0000 0.00009/29/2006 0.48 1.2192 1.0729 12/3/2006 0 0.0000 0.00009/30/2006 0 0.0000 0.0000 12/4/2006 0.19 0.4826 0.424711/1/2006 0.09 0.2286 0.2012 12/5/2006 0 0.0000 0.000011/2/2006 0.23 0.5842 0.5141 12/6/2006 0 0.0000 0.000011/3/2006 0 0.0000 0.0000 12/7/2006 0 0.0000 0.000011/4/2006 0 0.0000 0.0000 12/8/2006 0 0.0000 0.000011/5/2006 0 0.0000 0.0000 12/9/2006 0 0.0000 0.000011/6/2006 0 0.0000 0.0000 12/10/2006 0 0.0000 0.000011/7/2006 0.14 0.3556 0.3129 12/11/2006 0 0.0000 0.000011/8/2006 1.19 3.0226 1.6322 12/12/2006 0 0.0000 0.000011/9/2006 0.08 0.2032 0.1788 12/13/2006 0.1 0.2540 0.223511/10/2006 0 0.0000 0.0000 12/14/2006 0 0.0000 0.000011/11/2006 0 0.0000 0.0000 12/15/2006 0 0.0000 0.000011/12/2006 0.45 1.1430 1.0058 12/16/2006 0.01 0.0254 0.022411/13/2006 0.52 1.3208 1.1623 12/17/2006 0 0.0000 0.000011/14/2006 0.35 0.8890 0.7823 12/18/2006 0.02 0.0508 0.044711/15/2006 0 0.0000 0.0000 12/19/2006 0 0.0000 0.000011/16/2006 0.15 0.3810 0.3353 12/20/2006 0 0.0000 0.000011/17/2006 0.49 1.2446 1.0952 12/21/2006 0 0.0000 0.000011/18/2006 0 0.0000 0.0000 12/22/2006 0.06 0.1524 0.134111/19/2006 0 0.0000 0.0000 12/23/2006 0.81 2.0574 1.810511/20/2006 0 0.0000 0.0000 12/24/2006 0 0.0000 0.000011/21/2006 0 0.0000 0.0000 12/25/2006 0.09 0.2286 0.201211/22/2006 0 0.0000 0.0000 12/26/2006 0.34 0.8636 0.760011/23/2006 1.83 4.6482 2.5100 12/27/2006 0 0.0000 0.000011/24/2006 0.27 0.6858 0.6035 12/28/2006 0 0.0000 0.000011/25/2006 0 0.0000 0.0000 12/29/2006 0 0.0000 0.000011/26/2006 0 0.0000 0.0000 12/30/2006 0.08 0.2032 0.178811/27/2006 0 0.0000 0.0000 12/31/2006 0 0.0000 0.000011/28/2006 0.01 0.0254 0.0224 11/29/2006 0 0.0000 0.000011/30/2006 0 0.0000 0.0000
1/1/2007 0.86 2.1844 1.9223 2/1/2007 0 0.0000 0.00001/2/2007 0 0.0000 0.0000 2/2/2007 0.19 0.4826 0.42471/3/2007 0 0.0000 0.0000 2/3/2007 0.06 0.1524 0.13411/4/2007 0 0.0000 0.0000 2/4/2007 0 0.0000 0.00001/5/2007 0.01 0.0254 0.0224 2/5/2007 0 0.0000 0.00001/6/2007 0.07 0.1778 0.1565 2/6/2007 0 0.0000 0.00001/7/2007 0 0.0000 0.0000 2/7/2007 0 0.0000 0.00001/8/2007 0.57 1.4478 1.2741 2/8/2007 0 0.0000 0.00001/9/2007 0 0.0000 0.0000 2/9/2007 0 0.0000 0.0000
1/10/2007 0 0.0000 0.0000 2/10/2007 0 0.0000 0.00001/11/2007 0 0.0000 0.0000 2/11/2007 0 0.0000 0.00001/12/2007 0 0.0000 0.0000 2/12/2007 0 0.0000 0.00001/13/2007 0.06 0.1524 0.1341 2/13/2007 0 0.0000 0.00001/14/2007 0.13 0.3302 0.2906 2/14/2007 1.62 4.1148 2.22201/15/2007 0.64 1.6256 1.4305 2/15/2007 0 0.0000 0.00001/16/2007 0.06 0.1524 0.1341 2/16/2007 0 0.0000 0.00001/17/2007 0 0.0000 0.0000 2/17/2007 0 0.0000 0.00001/18/2007 0 0.0000 0.0000 2/18/2007 0 0.0000 0.00001/19/2007 0 0.0000 0.0000 2/19/2007 0 0.0000 0.00001/20/2007 0 0.0000 0.0000 2/20/2007 0 0.0000 0.00001/21/2007 0 0.0000 0.0000 2/21/2007 0 0.0000 0.00001/22/2007 0.02 0.0508 0.0447 2/22/2007 0.02 0.0508 0.04471/23/2007 0 0.0000 0.0000 2/23/2007 0.01 0.0254 0.02241/24/2007 0 0.0000 0.0000 2/24/2007 0 0.0000 0.00001/25/2007 0 0.0000 0.0000 2/25/2007 0 0.0000 0.00001/26/2007 0 0.0000 0.0000 2/26/2007 0.3 0.7620 0.67061/27/2007 0 0.0000 0.0000 2/27/2007 0 0.0000 0.0000
104
1/28/2007 0.02 0.0508 0.0447 2/28/2007 0 0.0000 0.00001/29/2007 0 0.0000 0.0000 4/1/2007 0.17 0.4318 0.38001/30/2007 0 0.0000 0.0000 4/2/2007 0.15 0.3810 0.33531/31/2007 0 0.0000 0.0000 4/3/2007 0.01 0.0254 0.02243/1/2007 0 0.0000 0.0000 4/4/2007 0.94 2.3876 2.10113/2/2007 1.48 3.7592 2.0300 4/5/2007 0.27 0.6858 0.60353/3/2007 0 0.0000 0.0000 4/6/2007 0 0.0000 0.00003/4/2007 0 0.0000 0.0000 4/7/2007 0 0.0000 0.00003/5/2007 0 0.0000 0.0000 4/8/2007 0 0.0000 0.00003/6/2007 0 0.0000 0.0000 4/9/2007 0 0.0000 0.00003/7/2007 0 0.0000 0.0000 4/10/2007 0 0.0000 0.00003/8/2007 0 0.0000 0.0000 4/11/2007 0 0.0000 0.00003/9/2007 0 0.0000 0.0000 4/12/2007 0.87 2.2098 1.9446
3/10/2007 0 0.0000 0.0000 4/13/2007 0 0.0000 0.00003/11/2007 0.27 0.6858 0.6035 4/14/2007 0 0.0000 0.00003/12/2007 0 0.0000 0.0000 4/15/2007 1.42 3.6068 1.94773/13/2007 0 0.0000 0.0000 4/16/2007 0.93 2.3622 2.07873/14/2007 0 0.0000 0.0000 4/17/2007 0.16 0.4064 0.35763/15/2007 0.12 0.3048 0.2682 4/18/2007 0.05 0.1270 0.11183/16/2007 0.42 1.0668 0.9388 4/19/2007 0 0.0000 0.00003/17/2007 1.46 3.7084 2.0025 4/20/2007 0 0.0000 0.00003/18/2007 0 0.0000 0.0000 4/21/2007 0 0.0000 0.00003/19/2007 0.05 0.1270 0.1118 4/22/2007 0 0.0000 0.00003/20/2007 0.02 0.0508 0.0447 4/23/2007 0 0.0000 0.00003/21/2007 0 0.0000 0.0000 4/24/2007 0 0.0000 0.00003/22/2007 0 0.0000 0.0000 4/25/2007 0.17 0.4318 0.38003/23/2007 0 0.0000 0.0000 4/26/2007 0 0.0000 0.00003/24/2007 0.34 0.8636 0.7600 4/27/2007 1.06 2.6924 1.45393/25/2007 0 0.0000 0.0000 4/28/2007 0.37 0.9398 0.82703/26/2007 0.11 0.2794 0.2459 4/29/2007 0.06 0.1524 0.13413/27/2007 0.04 0.1016 0.0894 4/30/2007 0.08 0.2032 0.17883/28/2007 0 0.0000 0.0000 6/1/2007 0.15 0.3810 0.33533/29/2007 0 0.0000 0.0000 6/2/2007 0 0.0000 0.00003/30/2007 0 0.0000 0.0000 6/3/2007 0.11 0.2794 0.24593/31/2007 0 0.0000 0.0000 6/4/2007 1.46 3.7084 2.00255/1/2007 0 0.0000 0.0000 6/5/2007 0 0.0000 0.00005/2/2007 0.08 0.2032 0.1788 6/6/2007 0 0.0000 0.00005/3/2007 0 0.0000 0.0000 6/7/2007 0 0.0000 0.00005/4/2007 0 0.0000 0.0000 6/8/2007 0 0.0000 0.00005/5/2007 0 0.0000 0.0000 6/9/2007 0 0.0000 0.00005/6/2007 0 0.0000 0.0000 6/10/2007 0 0.0000 0.00005/7/2007 0 0.0000 0.0000 6/11/2007 0.01 0.0254 0.02245/8/2007 0 0.0000 0.0000 6/12/2007 0.07 0.1778 0.15655/9/2007 0 0.0000 0.0000 6/13/2007 0 0.0000 0.0000
5/10/2007 0 0.0000 0.0000 6/14/2007 0 0.0000 0.00005/11/2007 0.07 0.1778 0.1565 6/15/2007 0 0.0000 0.00005/12/2007 0 0.0000 0.0000 6/16/2007 0 0.0000 0.00005/13/2007 0 0.0000 0.0000 6/17/2007 0.02 0.0508 0.04475/14/2007 0 0.0000 0.0000 6/18/2007 0 0.0000 0.00005/15/2007 0.09 0.2286 0.2012 6/19/2007 0 0.0000 0.00005/16/2007 0.79 2.0066 1.7658 6/20/2007 0.16 0.4064 0.35765/17/2007 0 0.0000 0.0000 6/21/2007 0.09 0.2286 0.20125/18/2007 1.72 4.3688 2.3592 6/22/2007 0.03 0.0762 0.06715/19/2007 0.43 1.0922 0.9611 6/23/2007 0 0.0000 0.00005/20/2007 0.52 1.3208 1.1623 6/24/2007 0 0.0000 0.00005/21/2007 0 0.0000 0.0000 6/25/2007 0 0.0000 0.00005/22/2007 0 0.0000 0.0000 6/26/2007 0 0.0000 0.00005/23/2007 0 0.0000 0.0000 6/27/2007 0 0.0000 0.00005/24/2007 0 0.0000 0.0000 6/28/2007 0.02 0.0508 0.04475/25/2007 0 0.0000 0.0000 6/29/2007 0 0.0000 0.00005/26/2007 0 0.0000 0.0000 6/30/2007 0 0.0000 0.00005/27/2007 0 0.0000 0.0000 8/1/2007 0 0.0000 0.00005/28/2007 0 0.0000 0.0000 8/2/2007 0 0.0000 0.00005/29/2007 0 0.0000 0.0000 8/3/2007 0 0.0000 0.00005/30/2007 0 0.0000 0.0000 8/4/2007 0 0.0000 0.00005/31/2007 0 0.0000 0.0000 8/5/2007 0 0.0000 0.00007/1/2007 0.21 0.5334 0.4694 8/6/2007 0 0.0000 0.00007/2/2007 0 0.0000 0.0000 8/7/2007 0 0.0000 0.00007/3/2007 0 0.0000 0.0000 8/8/2007 0.28 0.7112 0.6259
105
7/4/2007 0.05 0.1270 0.1118 8/9/2007 0 0.0000 0.00007/5/2007 0.31 0.7874 0.6929 8/10/2007 0.09 0.2286 0.20127/6/2007 0 0.0000 0.0000 8/11/2007 0 0.0000 0.00007/7/2007 0 0.0000 0.0000 8/12/2007 0 0.0000 0.00007/8/2007 0.02 0.0508 0.0447 8/13/2007 0 0.0000 0.00007/9/2007 0.23 0.5842 0.5141 8/14/2007 0 0.0000 0.0000
7/10/2007 0 0.0000 0.0000 8/15/2007 0 0.0000 0.00007/11/2007 0.01 0.0254 0.0224 8/16/2007 0 0.0000 0.00007/12/2007 0.05 0.1270 0.1118 8/17/2007 0 0.0000 0.00007/13/2007 0 0.0000 0.0000 8/18/2007 0.04 0.1016 0.08947/14/2007 0 0.0000 0.0000 8/19/2007 0 0.0000 0.00007/15/2007 0 0.0000 0.0000 8/20/2007 0 0.0000 0.00007/16/2007 0 0.0000 0.0000 8/21/2007 0 0.0000 0.00007/17/2007 0 0.0000 0.0000 8/22/2007 0 0.0000 0.00007/18/2007 0.17 0.4318 0.3800 8/23/2007 0 0.0000 0.00007/19/2007 0.11 0.2794 0.2459 8/24/2007 0 0.0000 0.00007/20/2007 0.01 0.0254 0.0224 8/25/2007 0 0.0000 0.00007/21/2007 0 0.0000 0.0000 8/26/2007 0 0.0000 0.00007/22/2007 0 0.0000 0.0000 8/27/2007 0 0.0000 0.00007/23/2007 0.06 0.1524 0.1341 8/28/2007 0 0.0000 0.00007/24/2007 0 0.0000 0.0000 8/29/2007 0 0.0000 0.00007/25/2007 0 0.0000 0.0000 8/30/2007 0 0.0000 0.00007/26/2007 0 0.0000 0.0000 8/31/2007 0.01 0.0254 0.02247/27/2007 0 0.0000 0.0000 10/1/2007 0 0.0000 0.00007/28/2007 2.32 5.8928 3.1821 10/2/2007 0 0.0000 0.00007/29/2007 0 0.0000 0.0000 10/3/2007 0 0.0000 0.00007/30/2007 1.72 4.3688 2.3592 10/4/2007 0 0.0000 0.00007/31/2007 0 0.0000 0.0000 10/5/2007 0 0.0000 0.00009/1/2007 0 0.0000 0.0000 10/6/2007 0 0.0000 0.00009/2/2007 0 0.0000 0.0000 10/7/2007 0 0.0000 0.00009/3/2007 0 0.0000 0.0000 10/8/2007 0.64 1.6256 1.43059/4/2007 0 0.0000 0.0000 10/9/2007 0.01 0.0254 0.02249/5/2007 0 0.0000 0.0000 10/10/2007 0.04 0.1016 0.08949/6/2007 0 0.0000 0.0000 10/11/2007 0.29 0.7366 0.64829/7/2007 0 0.0000 0.0000 10/12/2007 0.04 0.1016 0.08949/8/2007 0 0.0000 0.0000 10/13/2007 0 0.0000 0.00009/9/2007 0.03 0.0762 0.0671 10/14/2007 0 0.0000 0.0000
9/10/2007 0.01 0.0254 0.0224 10/15/2007 0 0.0000 0.00009/11/2007 1.28 3.2512 1.7556 10/16/2007 0 0.0000 0.00009/12/2007 0 0.0000 0.0000 10/17/2007 0 0.0000 0.00009/13/2007 0 0.0000 0.0000 10/18/2007 0 0.0000 0.00009/14/2007 0 0.0000 0.0000 10/19/2007 0.42 1.0668 0.93889/15/2007 0.34 0.8636 0.7600 10/20/2007 0.12 0.3048 0.26829/16/2007 0 0.0000 0.0000 10/21/2007 0 0.0000 0.00009/17/2007 0 0.0000 0.0000 10/22/2007 0 0.0000 0.00009/18/2007 0 0.0000 0.0000 10/23/2007 0.01 0.0254 0.02249/19/2007 0 0.0000 0.0000 10/24/2007 0.04 0.1016 0.08949/20/2007 0 0.0000 0.0000 10/25/2007 0.01 0.0254 0.02249/21/2007 0 0.0000 0.0000 10/26/2007 0.02 0.0508 0.04479/22/2007 0 0.0000 0.0000 10/27/2007 0.44 1.1176 0.98359/23/2007 0 0.0000 0.0000 10/28/2007 0 0.0000 0.00009/24/2007 0 0.0000 0.0000 10/29/2007 0 0.0000 0.00009/25/2007 0 0.0000 0.0000 10/30/2007 0 0.0000 0.00009/26/2007 0 0.0000 0.0000 10/31/2007 0 0.0000 0.00009/27/2007 0.15 0.3810 0.3353 12/1/2007 0 0.0000 0.00009/28/2007 0 0.0000 0.0000 12/2/2007 0.04 0.1016 0.08949/29/2007 0 0.0000 0.0000 12/3/2007 0.53 1.3462 1.18479/30/2007 0 0.0000 0.0000 12/4/2007 0 0.0000 0.000011/1/2007 0 0.0000 0.0000 12/5/2007 0 0.0000 0.000011/2/2007 0 0.0000 0.0000 12/6/2007 0 0.0000 0.000011/3/2007 0 0.0000 0.0000 12/7/2007 0.03 0.0762 0.067111/4/2007 0 0.0000 0.0000 12/8/2007 0 0.0000 0.000011/5/2007 0 0.0000 0.0000 12/9/2007 0.04 0.1016 0.089411/6/2007 0 0.0000 0.0000 12/10/2007 0.06 0.1524 0.134111/7/2007 0 0.0000 0.0000 12/11/2007 0.06 0.1524 0.134111/8/2007 0.64 1.6256 1.4305 12/12/2007 0.01 0.0254 0.022411/9/2007 0.01 0.0254 0.0224 12/13/2007 0.86 2.1844 1.922311/10/2007 0.04 0.1016 0.0894 12/14/2007 0.01 0.0254 0.022411/11/2007 0.29 0.7366 0.6482 12/15/2007 0 0.0000 0.0000
106
11/12/2007 0.04 0.1016 0.0894 12/16/2007 0.74 1.8796 1.654011/13/2007 0 0.0000 0.0000 12/17/2007 0 0.0000 0.000011/14/2007 0 0.0000 0.0000 12/18/2007 0.01 0.0254 0.022411/15/2007 0 0.0000 0.0000 12/19/2007 0.06 0.1524 0.134111/16/2007 0 0.0000 0.0000 12/20/2007 0.49 1.2446 1.095211/17/2007 0 0.0000 0.0000 12/21/2007 0 0.0000 0.000011/18/2007 0.42 1.0668 0.9388 12/22/2007 0 0.0000 0.000011/19/2007 0.12 0.3048 0.2682 12/23/2007 0.49 1.2446 1.095211/20/2007 0 0.0000 0.0000 12/24/2007 0.01 0.0254 0.022411/21/2007 0 0.0000 0.0000 12/25/2007 0 0.0000 0.000011/22/2007 0.01 0.0254 0.0224 12/26/2007 0.18 0.4572 0.402311/23/2007 0.04 0.1016 0.0894 12/27/2007 0.42 1.0668 0.938811/24/2007 0.01 0.0254 0.0224 12/28/2007 0 0.0000 0.000011/25/2007 0.02 0.0508 0.0447 12/29/2007 0.15 0.3810 0.335311/26/2007 0.44 1.1176 0.9835 12/30/2007 0.09 0.2286 0.201211/27/2007 0 0.0000 0.0000 12/31/2007 0.47 1.1938 1.050511/28/2007 0 0.0000 0.000011/29/2007 0 0.0000 0.000011/30/2007 0 0.0000 0.0000
107
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