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Analysis of Net-Zero Energy Homes and Net-Zero Energy Communities in Hot and Humid Climates from the Builders Perspective

Permanent Link: http://ufdc.ufl.edu/UFE0025018/00001

Material Information

Title: Analysis of Net-Zero Energy Homes and Net-Zero Energy Communities in Hot and Humid Climates from the Builders Perspective
Physical Description: 1 online resource (108 p.)
Language: english
Creator: Lamb, Robert
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: building, communities, energy, florida, homes, near, net, zero
Building Construction -- Dissertations, Academic -- UF
Genre: Building Construction thesis, M.S.B.C.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science in Building Construction ANALYSIS OF NET-ZERO ENERGY HOMES AND NET-ZERO ENERGY COMMUNITIES IN HOT AND HUMID CLIMATES FROM THE BUILDERS PERSPECTIVE By Robert Lamb August 2009 Chair: Robert Ries Cochair: Charles Kibert Major: Building Construction This thesis studied the feasibility of net-zero energy homes (NZEH) and net-zero energy communities in hot and humid climates. This work focused on the problem statement from the perspective of the builder/developer. Feasibility was analyzed based on the cost per square foot to construct a single-family home in Gainesville, Florida to varying standards of energy efficiency. Energy-10 energy modeling software was used to evaluate energy reductions from the modeled Gainesville Baseline, to the Building America (BA) Best Practices, and proposed NZEH. The energy efficient home schemes targeted reductions, as compared to the Gainesville Baseline, of 30 % and 70 % respectively. The NZEH supplements the remaining 30 % of energy consumed via an onsite photovoltaic array (PV). The PV array was sized and modeled using PVWATTS v1 software. Once the energy efficient schemes achieved their targeted energy reductions, the incremental costs of the added efficiency measures were determined. These costs were then organized by total incremental cost, annual amortized cost, and increase in cost per square foot to construct. These costs were separated into those to the builder/developer and those to the homebuyer. The homebuyer costs included a 10 % markup from the builder/developer. Furthermore, the costs were separated into costs before rebates and incentives and costs after rebates and incentives. The final costs were compared against the calculated Gainesville average cost per square foot to construct a new single-family home in a typical community. The calculated Gainesville average cost per square foot to the homeowner before rebates and incentives was determined to be $146 while the BA Best Practices (30 % energy reduction) was $146.46, and the NZEH was $199.80. Without accounting for the rebates and incentives, NZEHs and NZECs were determined to not be feasible at this time. The cost per square foot to construct including rebates and incentives were $140.67 for the Gainesville Baseline, $140.80 for the BA Best Practices, and $167.04 for the NZEH. Including the rebates and incentives NZEHs and NZECs were determined to be feasible at this time.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Robert Lamb.
Thesis: Thesis (M.S.B.C.)--University of Florida, 2009.
Local: Adviser: Ries, Robert J.
Local: Co-adviser: Kibert, Charles J.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0025018:00001

Permanent Link: http://ufdc.ufl.edu/UFE0025018/00001

Material Information

Title: Analysis of Net-Zero Energy Homes and Net-Zero Energy Communities in Hot and Humid Climates from the Builders Perspective
Physical Description: 1 online resource (108 p.)
Language: english
Creator: Lamb, Robert
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: building, communities, energy, florida, homes, near, net, zero
Building Construction -- Dissertations, Academic -- UF
Genre: Building Construction thesis, M.S.B.C.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science in Building Construction ANALYSIS OF NET-ZERO ENERGY HOMES AND NET-ZERO ENERGY COMMUNITIES IN HOT AND HUMID CLIMATES FROM THE BUILDERS PERSPECTIVE By Robert Lamb August 2009 Chair: Robert Ries Cochair: Charles Kibert Major: Building Construction This thesis studied the feasibility of net-zero energy homes (NZEH) and net-zero energy communities in hot and humid climates. This work focused on the problem statement from the perspective of the builder/developer. Feasibility was analyzed based on the cost per square foot to construct a single-family home in Gainesville, Florida to varying standards of energy efficiency. Energy-10 energy modeling software was used to evaluate energy reductions from the modeled Gainesville Baseline, to the Building America (BA) Best Practices, and proposed NZEH. The energy efficient home schemes targeted reductions, as compared to the Gainesville Baseline, of 30 % and 70 % respectively. The NZEH supplements the remaining 30 % of energy consumed via an onsite photovoltaic array (PV). The PV array was sized and modeled using PVWATTS v1 software. Once the energy efficient schemes achieved their targeted energy reductions, the incremental costs of the added efficiency measures were determined. These costs were then organized by total incremental cost, annual amortized cost, and increase in cost per square foot to construct. These costs were separated into those to the builder/developer and those to the homebuyer. The homebuyer costs included a 10 % markup from the builder/developer. Furthermore, the costs were separated into costs before rebates and incentives and costs after rebates and incentives. The final costs were compared against the calculated Gainesville average cost per square foot to construct a new single-family home in a typical community. The calculated Gainesville average cost per square foot to the homeowner before rebates and incentives was determined to be $146 while the BA Best Practices (30 % energy reduction) was $146.46, and the NZEH was $199.80. Without accounting for the rebates and incentives, NZEHs and NZECs were determined to not be feasible at this time. The cost per square foot to construct including rebates and incentives were $140.67 for the Gainesville Baseline, $140.80 for the BA Best Practices, and $167.04 for the NZEH. Including the rebates and incentives NZEHs and NZECs were determined to be feasible at this time.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Robert Lamb.
Thesis: Thesis (M.S.B.C.)--University of Florida, 2009.
Local: Adviser: Ries, Robert J.
Local: Co-adviser: Kibert, Charles J.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0025018:00001


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1 ANALYSIS OF NET ZERO ENERGY HOMES AND NET ZERO ENERGY COMMUNITIES IN HOT AND HUMID CLIMATES FROM THE BUILDERS PERSPECTIVE By ROBERT LAMB A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FUL FILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN BUILDING CONSTRUCTION UNIVERSITY OF FLORIDA 2009

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2 2009 Robert Lamb

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3 To my parents: Robert Lamb, J ustine Bodmer, and Peter Bodmer W ithout their support none of this would ha ve been possible

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4 ACKNOWLEDGMENTS I would like to thank all those who assisted in the completion of this thesis, directly and indirectly. First, I would like to thank my thesis committee, which consists of Drs. Robert Ries, Charles Kibert, and Svetlana Olbina. Without their guidance, knowledge, and overall expertise I would not have been able to complete this work. Additionally, I would like to thank all those whom I contacted regarding this work for their patience and guidance. Furthermore, I woul d like to thank my girlfriend Valerie Robertson for putting up with me through the years and instilling confidence in myself. I would also like to thank Matt Hill for convincing me to switch to Building Construction, Joe Hart for exposing me to the notion of Sustainable Construction, and Ayesh Bhagvat for teaching me the value of rhetoric. I would also like to thank my grandmother Mary Barbara Marra for guidance given throughout the years. Finally, I would like to thank all my family and friends whom I havent mentioned for their support and indirect contributions to this work.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................8 LIST OF FIG URES .........................................................................................................................9 ABSTRACT ...................................................................................................................................10 CHAPTER 1 INTRODUCTION ..................................................................................................................12 2 LITERATURE REVIEW .......................................................................................................15 Introduction .............................................................................................................................15 Defining the Net Zero Energy Community ............................................................................15 DOE Energy Efficiency and Renewable Energy (EERE) Programs Addressing NZE ..........20 Heating, Ventilation, & Air Conditioning (HVAC) ...............................................................25 Liquid Desiccant Cooling System ...................................................................................27 Solar Assisted Desiccant Cooling System .......................................................................28 Domestic Water Heating .........................................................................................................30 Passive Solar Thermal System ........................................................................................32 Active Solar Thermal System ..........................................................................................34 Lighting ...................................................................................................................................35 Envelope .................................................................................................................................37 Attic System Goals ..........................................................................................................38 Wall System Goals ..........................................................................................................39 Foundation System Goals ................................................................................................39 New Materials Goals .......................................................................................................40 Windows .................................................................................................................................40 Dynamic Windows ..........................................................................................................42 Highly Insulated Windows ..............................................................................................43 Enabling Technology Research for Efficient Products ...................................................44 Daylighting and Advanced Faade Systems ...................................................................44 Photovoltaics (PV) ..................................................................................................................45 Building Integrated Photovoltaics ...................................................................................45 Building Applied Photovoltaics ......................................................................................46 Photovoltaic Constraints ..................................................................................................47 Photovoltaic Cost .............................................................................................................48 Improved Disaster Resistance .........................................................................................49 Progress toward Creating NZEC: Past and Present Projects ..................................................50 Premier Gardens ..............................................................................................................50 Other Builder/Developer Attempts ..................................................................................51 Gainesville, Florida: NZEC Prospect ..............................................................................51

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6 The Business Case for the Developmen t of NZECs ...............................................................52 3 METHODOLOGY .................................................................................................................61 Step 1: Literature Review .......................................................................................................61 Step 2: Determine Gainesvilles Baseline Cost/SF ................................................................61 Step 3: Identify the Bui lder/Developers Advantages & Goals ...............................................63 Builder/Developer Advantages .......................................................................................63 Builder/Developer Goals .................................................................................................64 Step 4: Energy 10 Development .............................................................................................65 Load P rofiles ...................................................................................................................65 Lighting ...........................................................................................................................66 Unit Conversion ...............................................................................................................66 Operating Conditions .......................................................................................................67 Step 5: Develop the Gainesville Baseline Home in Energy 10 ..............................................67 Step 6: Develop the BA Best Practices Home in Energy 10 ..................................................68 Step 7: Develop the NZEH in Energy 10 ...............................................................................69 Step 8: Determine Averages Annual Energy Consumption ...................................................70 Step 9: Quantify the Incremental Costs ..................................................................................71 Step 10: Determine Feasibility ...............................................................................................72 4 DATA ANALYSIS AND RESULTS ....................................................................................73 Gainesville Baseline versus BA Best Practices ......................................................................73 Gainesville Baseline versus NZEH ........................................................................................75 Photovoltaic Sizing .................................................................................................................76 BA Best Practices and NZEH Incremental Costs ...................................................................76 BA Best Practices ...................................................................................................................77 NZEH ......................................................................................................................................77 Gainesville Baseline, BA Best Practices, NZEH Comparison ...............................................78 Builder/Developer Costs .................................................................................................78 Homebuyer Costs ............................................................................................................80 5 SUMMARY, CONCLUSIONS, LIMITATIONS, AND RECOMMENDATIONS ..............83 Summary .................................................................................................................................83 Conclusions .............................................................................................................................84 Financial Feasibility Analysis .................................................................................................85 First Cost Ana lysis ..........................................................................................................85 Final Cost Analysis ..........................................................................................................86 Net Zero Energy Ready Communities ...................................................................................87 Limitations ..............................................................................................................................88 Holistic Feasibility Analysis ............................................................................................88 Quantifying Material and Time Reductions when Developing NZECs ..........................89 Energy 10 Limitations .....................................................................................................89 Recommendations for Future Research ..................................................................................90

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7 APPENDICES A GAINESVILLE BASELINE VS BA BEST PRACTICES ENERGY 10 DATA .................91 Energy 10 Input/Output ..........................................................................................................91 0 Degrees .........................................................................................................................91 90 Degrees .......................................................................................................................92 180 Degrees .....................................................................................................................93 270 Degrees .....................................................................................................................94 Example Comparative Bar Chart ............................................................................................95 B GAINESVILLE BASELINE VS NZEH ENERGY 10 DATA .............................................96 Energy 10 Input/Output ..........................................................................................................96 0 Degrees .........................................................................................................................96 90 Degrees .......................................................................................................................97 180 Degrees .....................................................................................................................98 270 Degrees .....................................................................................................................99 Example Comparative Bar Chat ...........................................................................................100 C PV WATTS DATA ..............................................................................................................101 D BA BEST PRACTICES INCREMENTAL COST ...............................................................102 E NZEH INCREMENTAL COST ...........................................................................................103 LIST OF REFERENCES .............................................................................................................104 BIOGRAPHICAL SKETCH .......................................................................................................108

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8 LIST OF TABLES Table page 21 Building America research g oals .......................................................................................23 22 Envelope subprogram roof/attic sys tem g oals by 2010 .....................................................39 23 Envelope subprogram wall system g oals by 2010 .............................................................40 24 Envelope s ubprog ram new envelope material g oals by 2010 ............................................40 25 Measured thin film BIPV efficiency, southern o rientation ...............................................46 26 Effects of the ARRA on residential PV .............................................................................49 31 Cost per sf to construct a new single family h ome ............................................................62 32 Energy efficiency of lighting f ixtures ................................................................................66 33 Gainesville baseline characteristics ...................................................................................68 34 BA best practices characteristics .......................................................................................69 35 NZEH c hara cteristics .........................................................................................................70 36 PVWATTS v1 i nputs .........................................................................................................71 41 Gainesville baseline energy 10 r esults ...............................................................................73 42 BA best practices energy 10 r esults ...................................................................................74 43 NZEH energy 10 r esults ....................................................................................................75 44 Averaged PVWATTS v1 simulation data, 7 kW DC ........................................................76

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9 LIST OF FIGURES Figure page 21 DOE EERE program h ierarchy ..........................................................................................22 22 DOE BA t imeline ...............................................................................................................24 23 DOE BA climate zones (subarctic, A laska not shown) .....................................................25 24 Typical h yb rid liquid desiccant cooling s ystem (DCS) .....................................................28 25 Solar desiccant cooling s ystem (SDCS) ............................................................................30 26 Typical thermosiphon domestic hot water s ystem .............................................................34 27 A ) Typical ASDS i nstall, B ) Typical drainback s ystem ................................................35 28 BT windows subprogram perfo rmance g oals ....................................................................42 41 Gainesville baseline v. BA best practices averaged annual energy use .............................74 42 Gainesville baseline v. NZEH averaged annual ener gy u se ..............................................75 43 Builder/developer incremental c osts ..................................................................................79 44 Builder/developer cost per sf to c onstruct .........................................................................79 45 Homebuyer incremental first c ost ......................................................................................80 46 Homebuyer first/final cost/sf to c onstruct ..........................................................................81 47 Homebuyer rebates and i ncentiv es ....................................................................................82 48 Homebuyer first and final complete c osts .........................................................................82

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10 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science in Building Construction ANALYSIS OF NET ZERO ENERGY HOMES AND NET ZERO ENERGY COMMUNITIES IN HOT AND HUMID CLIMATES FROM THE BUILDERS PERSPECTIVE By Robert Lamb August 2009 Chair: Robert Ries Cochair: Charles Kibert Major: Building Construction This thesis studied the feasibility of netzero energy homes (NZEH) and net zero energy communities in hot and humid climates. This work focused on the problem statement from the perspective of the bu ilder/developer. Feasibility was analyzed based on the cost per square foot to construct a single family home in Gainesville, Florida to varying standards of energy efficiency. Energy 10 energy modeling software was used to evaluate energy reductions fro m the modeled Gainesville Baseline, to the Build ing America (BA) Best Practices, and proposed NZEH. The energy efficient home schemes targeted reductions, as compared to the Gainesville Baseline, of 30 % and 70 % respectively. The NZEH supplements the re maining 30 % of energy consumed via an onsite photovoltaic array (PV). The PV array was sized and modeled using PVWATTS v1 software. Once the energy efficient schemes achieved their targeted energy reductions, the incremental costs of the added efficien cy measures were determined. These costs were then organized by total incremental cost, annual amortized cost, and increase in cost per square foot to construct. These costs were separated into those to the builder/developer and those to the

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11 homebuyer. The homebuyer costs included a 10 % markup from the builder/developer. Furthermore, the costs were separated into costs before rebates and incentives and costs after rebates and incentives. The final costs were compared against the calculated Gainesville average cost per square foot to construct a new single family home in a typical community. The calculated Gainesville average cost per square foot to the homeowner before rebates and incentives was determined to be $146 while the BA Best Practices (30 % energy reduction) was $146.46, and the NZEH was $199.80. Without accounting for the rebates and incentives, NZEHs and NZECs were determined to not be feasible at this time. The cost per square foot to construct including rebates and incentives were $140.67 for the Gainesville Baseline, $140.80 for the BA Best Practices, and $167.04 for the NZEH. Including the rebates and incentives NZEHs and NZECs were determined to be feasible at this time.

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12 CHAPTER 1 INTRODUCTION A glutton in the truest sense of the w ord, the built environment consumes 30% of all primary energy in the United States. The associated burden (extract ing, processing, transporting) of gathering the energy necessary to satiate t his high demand belongs to the built environment as well. Furth ermore the spr awling unchecked growth of the built environment has led to increased dependency on automobiles. The b uilt environment consumes 40% of all materials annually extracted in the United States, and contains nearly 90% of all materials historically extracted (Kibert 2002). Waste generated through the constructi on and demolition (C/D) of the built environment contributes over 145 million metric tons (MMT) annually in the United States, nearly one third of all municipal solid waste. Of this C/D w aste about 92% can be linked directly t o demolition activities (Kibert 2002). Two other contributor s to the energy profile of the b uilt environment are the Ecological Rucksack and Embodied Energy inherent to all construction materials. On the low end of the spectrum, iron ore extraction has an Ecological Rucksack of 14:1. That ratio translates to disruption/displacement of 14 metric tons of waste material to produce 1 metric ton of iron (Kibert 2002). Taking these two principles into consideration, the amount of energy necessary to build a building is overwhelming. Society has only recently begun to pay attention to these metrics as ecosystems fail, materials dwindle, and energy prices rise. Consequently, the Sustainable Construction movement (read Gr een) was developed in an attempt to reduce the impact of the built environment. Reducing the impacts of the built environment is no simple task. One must approach the problem holistically, tackling it from social, environmental, and economic perspectiv es. Perhaps the single most impactful attribute of the b uilt environment is its energy profile. As described above, the amount of energy consumed, existing in and traveling through the buil t environment

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13 is astronomical. Additionally, the prevailing sour ce materials for energy are non renewable, radioactive, and contribute to global warming. Furthermore, these centralized energy sources are distributed through long, archaic transmission lines further reducing the efficiency of the cycle Sadly, at this time it is cost prohibitive to produce all the energy we need from sustainable sources. The demand is simply too high. Current building practices must be altered to make a sustainable energy platform viable in the future. The prevailing practice of desi gn ing a building to draw 100 kWh per square foot per year in the United States is unacceptable. Thankfully, there has been a large shift in the Construction Industry to design to higher standards, most of which are inherent to meeting USGBCs Leadership i n Energy and Environmental Design (LEED) criteria. We must continue to challenge the Industry to reach for standards like LEED, Factor 4, and Factor 10. Without a significant reduction in the current energy consumption of buildings a future of sustainabl y obtained renewable energy seems unlikely. It is imperative to research and develop construction materials and methods which will aide in the reduction of the built environments energy profile, therefore making the feasibility of these energy systems mor e viable. Combined, the commercial and residential sector of the built environment consumed $370 billion worth of energy in 2005. Moreover, the residential sector was the largest user, consuming 21.8 quads (1 Quad equals 293,071,000,000 kWhs) in 2005 ( DOE 2008). Reducing the energy profile of the residential sector will offer the most significant, and tangible benefits to society. While a reduction of energy consumption of any magnitude is a definite improvement, it is important for society to continually demand more from the built environment. If the demand for higher performing b uildings is demonstrated, then i ndustry professionals will deliver. The ultimate goal, in terms of energy consumption, is a net zero condition. In a net zero energy

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14 cir cum stance the building produces, onsite, as much energy as it uses over the course of a year. The purpose of this thesis is to demonstrate whether or not obtaining a net zero energy case in residential communities (NZEC) of hot and humid climates is feasible The building block of the NZEC is the net zero energy home (NZEH). For that reason, this work has examined the incremental cost to construct a NZEH. Additionally, this work has considered feasibility from the perspective of the builder/developer, and determines feasibility based on cost per square foot to construct a new single family home. A comprehensive literature review has been conducted. First, the review outlines the development of energy efficient homes in the United States. Then it discusse s the Department of Energys (DOE) Building Technology (BT) and Building America (BA) programs. These government funded programs are paving the way to NZEHs and NZE Buildings by 2020 and 2025, respectively. Next, the review identifies the ideal areas for energy enhancement in residences and provides readily available material alternatives/systems vital to achieving NZE. Finally, the review states the business case for the development of NZEHs and NZECs. To evaluate feasibility of NZEC s three homes were developed; Gainesville Baseline, BA Best Practices and NZE H These homes were then modeled in Energy 10 software to determine their annual energy consumed and respective reduction in comparison to the baseline. In the NZEH, the remaining energy consumed was supplemented via an onsite photovoltaic (PV) system whose size was calculated using PVW ATTS v1 s imulation software. Cost to construct per square foot was then calculated based on all energy efficiency features incremental costs. Ultimately, feasibil ity was determined by compa ring the as designed cost per square foot to construct to t he prevailing market cost per square foot to construct a new single family home in typified communities. The results were analyzed, discussed, and recommendations were m ade.

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15 CHAPTER 2 LITERATURE REVIEW Introduction This literature review examine s the techniques and tech nology necessary to achieve net zero energy communities (NZEC) in hot and humid climates. The review present s the evolution of highefficiency homes in the United States (U.S.) and consequently define s the concept of the NZEC. Seco ndly, the review discusses the means and methods of achieving NZEC, focusing on the U.S. Department of Energy (DOE) Building Technologies (BT) and Building America (BA) program s. Next, the review analyzed the latest attempts at creating energy efficient communities. Finally, the review evaluated the environmental and business case for sustainability in the built environment; ultimately providing the basis for corporate adoptio n of the NZEC concept. Defining the Net Zero Energy Community The first section of the literature review outlined a brief overview of the history of energy efficient home design in the U.S., and the evolution toward NZEC. It documented the major trends an d their contributions to the evolving science of residential design; all the while emphasizing significant projects and case studies. The concept of a NZEC is relatively new, however interest in the reduction of energy consumption in the building sector originated just before World War II (Parke r 2009). The first studies aimed at reducing building energy consumption were carried out at the Massachusetts Institute of Technology (MIT) and focused on the use of solar energy to heat a structure. Through the se studies the MIT Solar House IV, built in 1959, was able to provide 57% of space and domestic water heating from the solar energy collected by 60 m2 of active solar collectors (Engebretson 1964).

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16 The next wave of development in the energy efficiency of homes in the United States was driven by the energy crisis of the 1970s. This era focused on passive solar heating features as a result of the high costs associated with active solar heating identified by the MIT Solar Houses. Passive systems implement ed during this time period used, insulated southoriented glazing systems with direct gain, indirect gain (e.g. Trombe walls) and attached sunspace features (Parker 2009, p. 513) The most important, and widely used, passive design strategy was thermal mass. Thermal mass operates by absorbing solar heat gain during the daytime and releasing the stored heat slowly throughout the night, providing space heating. The thermal mass was essential in providing interior comfort and reducing the demand for active thermal control systems (Balcomb 1984). The passive design strategies culminated in an average savings of 70% in additional space heating (SERI 1984). During this era the realization that an overall reduction in building energy demand, via more efficie nt building systems, coupled with solar heating efforts would yield the highest performing structure at the lowest overall cost (Balcomb 1986). The next evolutionary movement of energy efficient home design appeared with the implementation of superinsulate d homes. In cold and cloudy climates researchers made the correlation between higher levels of insulation and lower overall energy demand (Palmiter 1981). Parker (2009, p.513) summarizes the characteristics of super insulated homes: high insulation le vels for ceiling, walls and floor (typically RSI 18.8, 5.4 and 3.6 K m2/W or greater), very tight air construction and suntempering, with most of glass located on the south side of the building. Ventilation was provided by an air to air heat exchanger and target auxiliary design heat loads were a fraction o f the size of ordinary furnaces. A number of superinsulated homes were built and proved to be successful at relatively low incremental cost. The Saskatchewan House, built in Regina, Saskatchewan in 1 977, had no furnace and was able to thrive in the harsh environment. It quickly became the poster child for

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17 superinsulated homes, and did so for an incremental cost of approximately $6000 in 1982 (Parker 2009). This low incremental cost is consequence of the advanced passive design features and elimination of the entire furnace system. Another noteworthy experiment involved the construction of three 223 m2 superinsulated homes in Great Falls, Montana. In a climate with 4222 metric heating degree days the homes averaged 20 kWh/m2/year (Palmiter and Hanford 1985). Interest in superinsulated homes subsided as the cost of energy dropped during the 1980s. The superinsulated home movement was a great step forward in terms of residential energy efficiency. The focus within the passive solar and superinsulated home movements was to reduce the amount of energy used to heat a home. These approaches neglected reductions in cooling, water heating, and plug load energy profiles (Parker 2009). Without addressing these major consumers of energy, the overall efficiency of homes continued to suffer greatly. Enter the net zero energy home (NZEH) movement which aimed to combat the entire spectrum of residential inefficiencies. Once more, a NZEH is a residence which greatly reduces the energy consumption of the building through improved building techniques and materials and creates enough onsite energy to result in net zero energy use annually. The NZEH concept is driven by a low c ost of photovoltaic (PV) panels which are the primary means to generate onsite energy from the sun. It is important to note that PV is not the only option for onsite energy production; however it is the option which is most widely available regardless of climate. The closer the cost per uni t of energy gathered using PV to that of the electrical provider, the more feasible the PV panels become. During the 1980s the cost of onsite PV energy production declined, making the energy source more viable (Parker 2009). In the early 90s the cost p er p eak kW of PV was slightly above $6,000 (EIA 2003); currently the cost per peak kW hovers around $8,000. Consequently,

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18 in the 90s the Florida Solar Energy Center (FSEC) developed the Minimum Electricity Building (MEB) a home designed to aggressively r educe the amount of energy necessary to operate annually through an improved envelope and onsite PV, in a hot and humid climate. Due to the success of the MEB experiment t he FSEC speculated that a net zero energy condition could be achieved through the r eduction in energy demand and supplemental renewable onsite energy production (Parker and Dunlop 1994). One generalized method to reduce energy demand, and achieve NZE, is whole building design (WBD). When implemented, WBD can reduce the energy profile of a building by as much as 70%. WBD is related to integrated project delivery, when all parties responsible in the design, construction, and operation of a building collaborate throughout the building process. In essence, WBD ensures that every component or system of a building is complementary to one another (Fischer and Finnell 2007). For example, the lighting consultant would spec compact fluorescent bulbs in lieu of traditional incandescent bulbs to reduce internal heat gains which might negate the h igh efficiency HVAC system the mechanical engineer has selected. Renewable onsite energy production can be achieved through a variety of methods. As mentioned, the type of energy producing system implemented is dictated directly by the site and its avai lable natural resources. Examples of readily available renewable onsite energy systems include PV, solar thermal, geothermal, and wind (Fischer and Finnell 2007). Once the project team has determined which system is ideal for their project, the system is installed and tied into the grid. Most utility providers bill via the net metering concept, where you pay for the amount of power you take from the grid. When a NZEH is creating more energy than it is using the power is fed into the grid and, via the ne t metering concept, the excess energy is subtracted from the gross energy needs. Fischer and Finnell (2007, p. 8) explain, If a home generates more

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19 power in one month than it uses, the bill is zero or the extra kilowatt hours are carried over to summer o r winter months. Following the principles of WBD outlined above, in 1998 the FSEC designed a controlled experiment to test the feasibility of NZEHs. The FSEC built two homes in Lakeland, Florida with identical floor plans, constructed by the same builder The first home was designed and built conventionally to the prevailing code while the other, dubbed PVRES, was collaboratively designed and built exceeding the local code with the objective of obtaining NZE (Parker 2009). Some of the energy efficient f eatures of PVRES were, interior HVAC ductwork, a high efficiency heat pump, higher levels of wall insulation, a white reflective roofing system, solar water heating, efficient interior appliances and lighting, and a 4 kW DC PV system (Parker 2009, p. 513 ). To provide quantitative information the homes were precisely monitored for a period of one year. During that time period the PVRES home consumed 6960 kWh of grid derived electricity while producing 5180 kWh of onsite renewable energy from its PV array In contrast, the control home, through the same period of time, consumed 22600 kWhs (Parker 2009). While the PVRES home was unable to achieve a true NZE condition, the home demonstrated a 92% reduction in energy demand as compared to the control home (Parker 2009). The value of the study performed by the FSEC was immense. They proved that the concept of NZEH is technologically feasible. The project became the poster child for the DOEs Zero Energy Homes program. The programs overall goal is to ac hieve NZE via superinsulation, intelligent design, active and passive solar features, and high efficiency appliances/lighting (Parker 2009). Arguably the most successful attempt at a NZEH to date, the Habitat for Humanitys home in Wheat Ridge, Colorado w as able to achieve 1.1kWh/m2 over the course of a

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20 year in 2005, while remaining affordable (Parker 2009). Parker (2009, p. 515) highlights the small homes energy saving features; superinsulated with RSI 10.8 ceiling insulation, RSI 7.2 double stud walls and RSI 5.4 floor insulation (Fig. 6). Ventilation is provided by a small heat recovery ventilator. Very high performance low e solar glass with argon fill and a U factor (SI) of 1.14W/m2 K was used for the east, west and north faces with a higher solar t ransmission U factor 1.70 glass used for the south exposure. The home used a 9m2 solar collector with 757 L of storage, backed up by a tankless gas water heater. The home was mated with a 4 kW roof top PV system. Data was collected for a year and during t hat time the PV system produced 1542 kWh more than was needed to operate the home. However, the home consumed 57 therms (about 1700 kWh) of natural gas resulting in the 1.1 kWh/m2/year figure. Additionally, the homes incremental cost was $42,500 which i ncludes the cost of all onsite energy systems. However the total incremental cost minus the onsite energy systems was only about $3,400 (Parker 2009). As demonstrated, the NZEH is the building block for the NZEC. To achieve a NZEC you simply develop homes which achieve NZE and multiply per the desired density. The difficulty is identifying and satisfying the developers goals for building communities at greater initial cost. Thankfully, the available research has proven that NZEHs are technological ly feasible. The quintessential example above the Habitat for Humanity case study, has proven that a very near zero energy home is technologically feasible at a small incremental cost. Due to the success of such research efforts, the DOE has invested im mensely in the concept of reducing the energy profile of the residential sector. Their solution, the Building Technologies (BT) and Building America (BA) programs, strive to provide a prescriptive means and methods to create a NZEH. DOE Energy Efficien cy and Renewable Energy (EERE) Programs Addressing NZE This second section of the literature review has focus ed on the available means and methods to creating NZEH, the building blocks of NZEC. It will concentrate on the DOEs

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21 Building Technologies (BT) and Building America (BA) programs as an emerging prescriptive guideline to achieve NZE Hs Additionally, this section will identify, and explain in detail, specific systems and technologies vital in achieving NZEC. BT is the umbrella organization to BA and is responsible for defining the problems and creating the solutions necessary to achieve NZE in the residential sector by 2020 (DOE 2008). BA focuses on information and technology which can be implemented in the now, whereas BT plans ahead and strives to identify new methods and evaluate innovative technologies to achieve the tiered energy reduction goals on time. The BT program is broader in scope than BA, and addresses energy reduction in the Commercial and Residential building sectors (DOE 2008). C ombined, the two sectors energy demand in 2005 was valued at $370 billion. Reducing said demand can drastically reduce Americas vulnerability to energy supply disruptions and fluctuations in the price of energy (DOE 2008). The BT programs mission state ment is to achieve NZE for the residential sector by 2020, and 2025 for the commercial sector. This review will focus on the BTs agenda for achieving NZE in the residential sector by 2020. BT tackles this challenge via three main areas of activity: Research and Development, Equipment Standards and Analysis, and Technology Validation and Market Introduction (DOE 2008). Research and Development (R&D) under BT is conducted via, a balanced portfolio of high risk and applied research to accelerate the int roduction of energy efficient building technologies and practices (DOE 2008, p. 21). The program evaluates potential gains in efficiency via two trains of thought: R&D of systems integration, and individual building components. Systems integration focuses on the interaction between building systems to improve efficiency while R&D of individual components evaluates the building blocks within the systems (DOE 2008). To create precisely targeted subprograms and develop relevant

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22 strategies to achieve energ y efficiency BT i mplements whole building design which accounts for the complex relationship between building and its environment, and the Stage Gate methodology which sets goals for a project, aka gates, which will be evaluated against pre determined dat a to conclude if the project will be approved for the next phase, rejected, or recycled (DOE 2008). The Residential Integration (RI) subprogram is responsible for R&D applied to the residential sector; and BA is the primary program within RI (Figure 2 1). Figure 2 1. DOE EERE program h ierarchy The DOEs Building America program (BA) is a government funded, industry driven research program focused on reducing the overall environmental impact of the U.S. Residential Sector. The program places a strong emp hasis on tiered reductions in residential buildings energy consumption over time. The mission statement of BA is, reengineering new and existing American homes for energy efficiency, energy security, and affordability (DOE 2009a) The program is founded on the systems engineering approach which is very similar to the WBD approach described earlier in this review. In essence, the BA teams make design decisions based on the interactions between all main building systems; the building envelope, mechanical s ystems, landscaping, neighboring houses, orientation, climate, lighting systems, and so on (DOE 2009a). The research goals of BA are comprehensive and can be viewed in Table 2 1. Goals one and two are most relevant to this literature reviews scope.

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23 T able 2 1. B uilding America research g oals DOE BA Research Goals 1) Produce homes on a community scale that use on average 40% to 100% less source energy 2) Integrate onsite power systems leading to zero energy homes, that produce as much energy as they use, by 2020 3) Improve indoor air quality and comfort 4) Help home builders reduce construction time and waste 5) Implement innovative energy and material saving technologies 6) Improve builder profitability 7) Provide new product opportunities to manufacturers and suppliers 8) Dramatically increase the energy efficiency of existing homes. Sourced from (DOE 2009b) The program has developed a set of target energy reductions, or tiers. The BA program aims to achieve a reduction in whole hous e energy use of 40% in 2010, 50% in 2015, and 70% in 2020. These reductions have been graphically represented and can be viewed in Figure 22 ( DOE 2009c). These reductions are compared against the Building America Benchmark and are calculated as an avera ge of the applicable homes. It is important to understand that the values will be compared on average, as it would be cost prohibitive to design a NZEH for every homeowner The behavior of each homeowner is unique and represents the largest variable in e nergy demand within the program guidelines. If the homeowner does not buy in to the inherent tradeoffs of living in a NZEH, then the buildings efficiency will suffer. In other words, BA expects to realistically achieve an average of a 95 % reduction in 2020 as a result of this behavioral inconsistency. However, they anticipate a significant number of true NZEH offsetting the less efficient, higher than normal occupancy derived load, homes. This assumption ensures the goal of NZE Hs in 2020 is still feasib le (DOE 2008). Another noteworthy condition is that these reductions in energy must be met at neutral cash flow to the owner. To define neutral cash flow we must first define net cash flow as BA sees it. BA defines net cash flow as,

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24 the monthly mortgage payment for energy options minus the monthly utility bill cost savings (DOE 2008, p. 26). Neutral cash flow is achieved when the difference between the additional costs of the energy saving options minus the savings in utility cost equals zero. In ot her words, your net cash flow is zero or better as averaged over the year (DOE 2008). Logically, this means that the incremental cost of the added efficiency measures pay for themselves each and every month. The program estima tes that homes can realize a 70 % reduction in overall energy consumed and 30 % onsite energy production by the year 2020, thus resulting in a NZEH. Figure 2 2. DOE BA t imeline To achieve this goal the program continually develops and publishes a series of Best Practices (BP), wh ich can be used to achieve the tiered energy reductions, specific to a variety of climates. There are a total of eight climates classified by BA: cold, very cold, hot dry, mixeddry, hot humid, marine, subarc tic, and mixed humid. The climate zones can be seen in Figure 2 3 (DOE 2009d). The program excludes development in the very cold and subarctic climates due to lack of residential growth (DOE 2008). Currently, if followed, the BPs are able to achieve a

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25 30% reduction of overall energy demand for the defined climates; far from the programs go al of a 70% reduction by 2020 (Baechler, 2005). Figure 2 3. DOE BA climate zones (subarctic, Alaska not shown) The BA program is quickly spreading through the U.S, currently active in thirty six states with 40,371 projects totaling over 989 Billion BTUs saved (DOE 2008). In 2005 the U.S. consumed 100.2 quads of energy with 40% being attributable to the built environment. Within this built environment the residential sector represented 55% of the energy, making it the largest consumer of energy at 21.8 quads (DOE 2008). Approximately 80% of the energy consumed in the residential sector is done so by single family homes and this market segment is expected to grow and account for over 70% of all new housing units (DOE 2008). As a result of this observation BA tailors its R&D efforts toward single family homes. BA identifies the three largest end uses of energy in single family homes as space heating and cooling, water heating, and lighting. Consequently, the BT program has implemented subprograms for each of t hese critical areas of R&D. This review examine s the DOE subprogram R&D efforts, as well as outside recommendations to reduce the energy profile of these systems. Heating, Ventilation, & Air Conditioning (HVAC) Within BT, HVAC and Water Heating have their own subprogram whose R&D is directed toward addressing the critical needs of the N ZEH movement (DOE 2008). This

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26 literature review has separated the two major consumers of energy to provide a clear analys is and allow for exploration of technologies beyond the scope of the BT program. HVAC loads are the number one consumer of energy in the residential and commercial sectors. A dramatic increase in the efficiency of these appliances is essential to the suc cess of the BT program objectives. It would be cost prohibitive to design a home to operate at NZE using conventional HVAC equipment, the cost/size of the onsite energy system needed to offset the demand created by the unit would be too great (DOE 2008). When combined, the commercial and residential sectors operation of HVAC equipment accounts for approximately 38.6 % of the total amount of energy used in buildings; totaling 15.34 quads (DOE 2008). Within the residential sector space heating consumes th e most energy, 30.7 % whereas space cooling accounts for 12.3 % (DOE 2008). In order to achieve the NZEH goal defined by BA HVAC systems need to become 50 % more efficient, as compared to the BA 2004 Benchmark, by 2010 (DOE 2008). Developments in HVAC e fficiency have been unimpressive and driven by increasing minimum efficiency standards, the last occurring in January of 2006 specifying a minimum 13 SEER rating (DOE 2008). The HVAC subprogram identifies several market challenges and barriers limiting pe netration and development of high efficiency HVAC units. The most apparent limitation is the higher first cost of high efficiency systems. In addition to greater cost, premium HVAC units are touted as: providing improved air filtration, reduced noise, and better fit and finish. These features represent what the market is currently demanding, and often have little benefit to overall system efficiency (DOE 2008). These touted benefits create a pseudo premium unit, once which offers no ga in in efficiency b ut is sold at a higher price. Efficiency gains in HVAC equipment are particularly difficult to comprehend and quantify in a NZE condition as the load which will be imposed on the system is much lower than

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27 what is conventional. HVAC equipment efficiency t ends to lessen as system capacity is reduced. This is due to losses related to, clearance volume flow in compressors and highto low pressure section leakage in reversing valves (DOE 2008, p. 240). In addition to this problem, controlling humidity in a NZEH will prove to be difficult with conventional HVAC equipment, due to the tight envelope (DOE 2008). The tighter the envelope, the fewer air changed per hour which allows moisture to accumulate and cause indoor air quality problems. The subprogram recognizes that radically new ideas and systems are necessary to solve the HVAC conundrum. Preliminary investigations into innovative techniques and systems are: reduction of distributional losses and recovery of waste heat, stand alone direct expansio n dehumidification systems with energy recovery ventilation, low leakage thermal loss duct systems, low capacity space conditioning system that may be integrated with night cooling or other evaporative cooling options, combined desiccant/evaporative cooling unit to supply any mix of sensible and latent loads in any climate (DOE 2008, p. 241). The RI program has identified 24 SEER systems with substantial dehumidification capabilities as the target if NZE is to be realized by 2020 (DOE 2008). A potentia l technology to aide in dehumidification, increase HVAC efficiency, and improve thermal comfort is desiccant cooling. Liquid Desiccant Cooling System In any climate your perception of thermal comfort is dictated by two factors, the temperature and humidity However, if two rooms in a hot and humid climate were conditioned to the same temperature, but room B had a lower relative humidity; occupants would feel more comfortable in room B (Toolbase 2009). This observation is the driving force behind desiccant cooling technologies. The load imposed on an HVAC system is a combination of sensible load and latent load. In hot and humid climates HVAC cooling loads are dominated by the latent load. The latent load is the load due to condensation and removal of moisture from the air. By combining a traditional vapor compression system and a desiccant dehumidification system reductions in overall electrical consumption for cooling are possible (Mago et al 2006). Hybrid

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28 liquid desiccant cooling systems (DCS) opera te on a thermally driven, open cycle. The concept behind DCS is not new, and the system has found implementation in multiple sustainable commercial applications. A typical systems dia gram can be viewed in Figure 24 (Halliday et al 2000). Figure 2 4. Typical hybrid liquid desiccant cooling s ystem (DCS) DCS have proven to reduce the compressor power consumption by up to 25% with an evaporation and condensation area reduction of up to 34% (Feyka and Vafai 2007). Solar Assisted Desiccant Cooling System A more novel approach involves the integration of solar thermal energy to regenerate the desiccant. The basic process of solar assisted desiccant cooling systems (SDCS) is very similar to the above example. Solair (2009), a project financed under Intell igent Energy Europe with thirteen EU partners whose focus is increasing the market implementation of solar air conditioning systems for small and medium applications in residential and commercial buildings, eloquently describes the SDCS process as:

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29 Warm and humid air enters the slowly rotating desiccant wheel and is dehumidified by adsorption of water (12). Since the air is heated up by the adsorption heat, a heat recovery wheel is passed (2 3), resulting in a significant pre cooling of the supply air s tream. Subsequently, the air is humidified and thus further cooled by a controlled humidifier (34) according to the set values of supply air temperature and humidity. The exhaust air stream of the rooms is humidified (67) close to the saturation point to exploit the full cooling potential in order to allow an effective heat recovery (7 8). Finally, the sorption wheel has to be regenerated (9 10) by applying heat in a comparatively low temperature range from 50 C 75 C and to allow a continuous operation of the dehumidification process. The process diagram for SD CS can be examined in Figure 2 5 (Solair 2009). The SDCS system is limited in its ability to remove humidity by the type of desiccant used. There are two generalized varieties, solid and liquid desiccants. Solid desiccants are appropriate for implementation in climates with mild to average amounts of humidity in the air, and have been studied relatively thoroughly. Special consideration and design approaches must be used when applying SDCS to hot and humid climate zones (Solair 2009). These climates are better suited to the liquid desiccant SDCS. Liquid desiccants, such as water lithium chloride solution, deliver a higher air dehumidification rate at the same operating temperature as solid des iccants. Efforts to quantify the advantages and identify appropriate applications of the emerging technology are currently underway in regions of Germany (Solair 2009). Implementation of SDCS offer many advantages and provide a means to have a significant impact on the overall efficiency of HVAC systems. However, to achieve NZE we must continue to analyze and develop ideas utilizing the WBD methodology, focusing on the improvement and interaction of all building systems. In this spirit we will examine technologies to reduce the second largest consumer of energy, as identified by BA, domestic hot water production.

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30 Figure 2 5. Solar desiccant cooling s ystem (SDCS) Domestic Water Heating Domestic Hot Water (DHW) production accounts for 12.2 % of energy consumption in residences, categorizing it as the second highest system consumer of energy in homes (DOE 2008). Dramatic improvements to the efficiency of DHW systems are necessary to achieve the BA program goal of NZE by 2020. The DHW subprogram of BT st ates that DHW systems need to attain reductions in energy consumption between 50 and 80 % relative to the BA Benchmark, to achieve NZE by 2020 (DOE 2008). Market barriers relative to the adoption of high efficiency DHW systems are even more daunting tha n HVAC systems. The impediment in marketing better DHW systems is the lack of tangible premium features. It is difficult for the manufacturer to substantiate the additional cost without proving any added comfort, aesthetics, image, or enhanced functional ity that can be coupled with the added energy efficiency (DOE 2008). Compounding the situation, DHW systems are most often purchased in an emergency situation forcing the consumer to settle for what is readily available from suppliers.

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31 Additionally, any new high efficiency DHW system must be able to provide significant energy reductions at a very low incremental cost in order to gain any market penetration. One of the most signific ant barriers to higher efficiency DH W systems is the relatively low cost t o operate conventional systems. A readily available higher efficiency DHW system is the electric heat pump DHW system. Due to the premium price attached to the higher efficiency heat pump systems, of the 4 to 5 million DHW systems sold annually in the U.S. only a few thousand are electric heat pump systems, even though they offer nearly double the effici ency of a traditional unit (DOE 2008.) The DHW subprogram recognizes that radically new ideas and systems are necessary to solve the DHW conundrum. Prel iminary investigations into innovative techniques and systems are: integration of tankless hot water systems; integration of simple, durable, low cost solar hot water systems; and acceptance of heat pump water heaters (DOE 2008 p. 241). For hot and humid climates the availability of solar thermal energy is abundant positioning solar thermal DHW systems as a promising renewable candidate for DHW production. There are two high level variants of solar thermal DHW systems (STS), direct and indirect sy stems. In a direct system the potable water is heated directly in the solar collector and distributed to the end user. Direct systems cannot be used in areas with hard or acidic water as Scale deposits would clog the system. An indirect system is closed loop and passes a heat transfer fluid through the collector and to a heat excha nger (NCSC 2002). A typical indirect STS is generally composed of flat plate solar collectors, an external heat exchanger, a temperature controller, and a storage tank with bac kup (Biaou and Bernier 2008). The backup energy source varies, typically with whatever is readily available, between electric, natural gas, diesel, wood,

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32 and so on. STS can be further categorized as either thermosiphon (passive) or pumped (active) system s. Passive Solar Thermal System Thermosiphon STS (TSTS) operate on the principal of natural circulation and represents the simpler of the two technologies (Kalogirou 2009). This type of system has gained wide acceptance abroad and is able to supply hot water at 140 F from solar radiation. A TSTS typically operates on an open loop cycle, heating and delivering potable water directly to the end user. In areas where freezing is a concern a freeze resistant heat transfer liquid can be used in lieu of pota ble water, however system efficiency often suffers. TSTS s heat potable water (or heat transfer fluid), via a solar collector, and utilize natural convection to move the fluid from the c ollector to storage (Kalogirou 2009). Kalogirou (2009, p. 41) explains thermosiphoning occurs when, the water (or heat transfer fluid) in the collector expands becoming less dense as heat is added by solar energy and rises through the collector header into the top of the storage tank. There it is replaced by the cooler water that has sunk to the bottom of the tank from which it flows down to the collector. This process will continue as long as the sun is shining and is driven by relatively small density differences, consequently larger than typical piping is necessary to reduce pipe friction (Kalogirou 2009). Systems are often designed to supply two days worth of hot water to account for fluctuations in solar insolation available. The fixed solar collectors are installed at an angle equal to the latitude of the location plus 5 (Kalogirou 2009). This has been determined to be the optimum tilt angle for yearlong performance. To account for extended periods of low solar insolation, such as winter, the systems are outfitted with a backup conventi onal heating element (Kalog irou 2009). The primary benefit of TSTS is that they can operate passively, utilizing zero electricity. The applicability of this technology in hot and

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33 humid climates in the U.S. to aide in achieving NZE is apparent; however TSTS marketability is limited by many factors. The largest barrier to the acceptance of these types of systems in the U.S. is their size. TSTS are relatively tall systems which are aesthetically less attractive than conventional and active solar systems (Kalogirou 2009). To maximi ze efficiency of the system, and prevent reversal of the thermosiphon process at night, it is imperative to place the storage tank well above the solar collector (Kalogirou 2009). Consequently, the systems are quite noticeable when installed on the roof of a residence. Internationally where these systems are popular (the Mediterranean) the built environment is denser than in the U.S. As a result, these bulky systems can more easily be installed out of sight, reducing their visual impact. However, single family homes in hot and humid climates are predominantly 12 stories with a pitched roof. The installation of a traditional TSTS would be very apparent and unattractive to homeowners. Certain TSTS systems can integrate the storage tanks into available a ttic space, however this creates its own set of problems to solve; such as the increased load from the large amount of water, additional piping, maintenance inaccessibility, and so on. The energy efficiency of TSTS is on the high end of the BT DHW subprog ram goal of reducing DHW loads by 50 to 80 % A conventional TSTS, as shown in Figure 26, has been proven to provide a reduction of 79 % in annual DHW energy used with a payba ck time of 2.7 years (Kalogirou 2009).

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34 Figure 2 6. Typical thermosiphon domes tic hot water s ystem Active Solar Thermal System Active solar DHW systems (ASDS) rely on the addition of an electric pump to move the fluid through the system (MREA 2009). As these types of systems are not relying on the natural process of thermosiphoning to move the fluid through the system, implementation is much less aesthetically intrusive as seen in Figure 2 7A (Allproducts 2009). Drainback systems represent a common approach when implementing indirect ASDS. Even in hot and humid climates freezing temperatures occur multiple times throughout the year. The Drain back system shown in Figure 27 B is designed to empty its collectors of water to avoid freezing damage when a freeze is eminent (NCSC 2002). To counteract the use of grid provided electrici ty some variants of ASDS integrate a PV powered pump with its own dedicated collector panels. The pump will consume PV electricity generated onsite when it is available and default to grid sourced power when onsite electrical demand is greater than onsite production (MREA 2009). Pumps used are able to operate directly on DC current, the power output of PV panels, which eliminates the AC to DC derate factor, boosting their efficiency. ASDS are able to reduce the amount of energy needed for DHW production by 40 to 70 % making them a viable alternative for the BA program. The

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35 systems cost ranges between two and five thousand dollars and, with regular inspection, should last for 20 to 30 years (MREA 2009). A B Figure 2 7. A) Typical ASDS i nstall B) Ty pical drainback s ystem Lighting Lighting systems constitute roughly 11% of residential building energy consumption, with the prevailing lighting technology being the archaic incandescent bulb. Consequently, lighting in residential buildings is the third largest direct consumer of electricity. Incandescent bulbs generate large amounts of heat during operation which negatively affects the cooling load of the home. Including this observation, the true consumption of lighting in the residential secto r could be as high as 40% (DOE 2008). To reduce the consumption of lighting in the residential market the DOE established the lighting subprogram of BT and has been researching solidstate lighting (SSL) and its applications in the built environment (DOE 2008). SSL is an emerging lighting technology which uses light emitting diodes (LED) and organic light emitting diodes (OLED) as sources of illumination. The term, solid state, is used as the light is emitted from a solid block of semiconductors, instead of the traditional vacuum or ga s filled tube and filament (DOE 2009e). The main difference between LED and OLED technology is that OLEDs are

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36 based on organic, carbon based materials and provide a diffuse area light source, as opposed to the d irect point source of LEDs (DOE 2009e). The DOE evaluates performance of the alternative lighting systems based on color rendering index (CRI), correlated color temperature ( CCT), and product lifetime (DOE 2008). In addition to these metrics, the program plac es great emphasis on the energy efficiency rating of the device. The metric of said measurement is lumens of light produced per w att of energy consumed (lm/W). The technical name for this measurement is efficacy, and many of todays lighting products are regulated using an efficacy target (DOE 2008). A typical incandescent bulb operates with an efficacy of 14 lumens per w att while readily available compact fluorescent bulb s operate around 60 lumens per w att. SSL technologies have the potential to reach efficacy ratings of 186 lumens per w att by the year 2015 (DOE 2008). Currently, SSL technology has an average operating lifetime of 50,000 hours. This represents lamp life double that of conventional linear fluorescent lighting, five times longer than co mpact fluorescent, and fifty times longe r than incandescent bulbs (DOE 2008). As a result of the longevity of the SSL systems their life cycle cost (LCC) is greatly reduced as compared to incandescent bulbs. In addition to the savings from a LCC perspect ive, the cost of SSL is expected to decrease from $25/klm in 2006 to $2/klm in 2015 (DOE 2008). LEDs have entered the marketplace and been met with great acceptance in the area of colored niche lighting. Areas of common application include traffic signal s, holiday lights, and commercial signage. Attractive characteristics include: energy savings, longer operational life, lower operating costs, improved durability, compact size, greater controllability, and faster on time (DOE 2008). Market penetration i s expected to increase and diversify as efficacy increases and costs decrease, ultimately being implemented into the residential building sector.

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37 Envelope The building envelope is the combination of the roof system, attic, walls, and foundation. The envelope separates the end user from the outdoors and its design and construction significantly impact the energy efficiency of a home. Building a home via traditional residential construction techniques, or to simply meet building code, represents the per vasive sentiment toward the building envelope in the residential sector. Many a homeowner expects to have a monthly utility bill, within a certain range, and has come to accept this as part of owning a home. A conventional residential envelope consists of a roof and truss system with blown in, loose fill fiberglass insulation, wood framed walls with 3.5 fiberglass batt resulting in R 11/R 13 insulation levels an d uninsulated foundation (DOE 2008). The BT R&D program realizes that redesign of the baseli ne envelope can yield significant efficiency gains. To address the advancement of residential envelope systems BT established the Envelope subprogram. The envelope is where the direct interaction between indoor conditioned space and outdoor air takes place. Ideally the envelope mitigates the transfer of thermal loss and gain while maintaining indoor comfort, with the least amount of energy being expended. The Envelope subprogram identifies heating and cooling loads in residential buildings as the number one consumer of primary energy in homes; consuming forty three % of all primary energy (DOE 2008). The magnitude of these heating and cooling loads is directly related to the insulating value of the envelope. The Envelope subprogram has developed and aligned its milestones as necessary to achieve NZE by 2020. The milestones promise to deliver new materials and enabling technologies in a timely manner. One such objective addresses the roof/attic system in single family homes, an area laden with energy loss. By 2015 the subprogram will develop advanced attic systems which will reduce the thermal losses caused by poor attic insulation by fifty % as compared to the BA Benchmark, at no additional operating cost or increa sed envelope

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38 failure risk (DOE 2008). Another goal of the subprogram is to develop advanced wall systems which will achieve R 25 and higher levels of insulation, with 40 % solar reflectivity at little incremental cost (DOE 2008). The Envelope subprogram also focuses heavily on maintaining the durability and reducing vulnerabilities of envelope materials. By 2015 it will have developed innovative materials which will improve the thermal performance of the envelope by 50 % relative to functionally comparable components of the Building Am erica regional ba seline new construction; or resolve durability related problems (moisture, termite, structural, etc.) that may increase envelope failure risk (DOE 2008, p. 2 46). In addition to these goals, the subprogram will encourage private industry investment in created new and innovative products; such as air barrier research and ASHRAE SP 160 Int erior Moisture Conditions (DOE 2008). Finally, the subprogram will advance the often overlooked foundation system by developing construction guidelines f or optimum foundation performance by 2015 (DOE 2008). The Envelope subprograms goal is to implement many of the planned improvements at, no additional operating cost. This is defined as the sum of the mortgage amortized installed cost and the a nnual e nergy cost savings (DOE 2008). The review will now examine the subprograms short term goals for each of the main envelope systems. Attic System Goals The Envelope subprograms short term goal for roofing and attic systems is to achieve twice the efficiency, as compared to the BA regional benchmarks, by 2010 (DOE 2008). The resulting system would achieve, on average, R 45. The subprogram places great emphasis on this building system because there is currently no documentation on how to achieve energy ef ficient attic systems. The attic system is defined as the space between the roof and finished ceiling and in cludes the roof structure (DOE 2008). To achieve this lofty goal by 2010 the subprogram has outlined its strategy which can be viewed in Table 2 2.

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39 Table 2 2 Envelope subprogram roof/attic system g oals by 2010 Envelope Subprogram Strategies for Next Generation Attic Systems by 2010 Integration of PCM, Cool Colors, ASV, Radiant Barrier and Advanced Lightweight Insulations Regionally Op timization of Above Sheathing Ventilation Best Practice for Integration of PCM in Roof and Attic Assembly Demonstration of Dynamically Active Roof and Attic Consolidation of Existing Energy Estimating Tools Sourced from (DOE, 2008) Wall Syste m Goals Next, the achievement of advanced wall systems by 2010 is driven by the development of wall assemblies which are more air tight and energy efficient. Again, the wall system represents another area where major improvements are necessary to achieve the goals of BA. By 2010, the subprogram will meet conventional insulation durability requirements while providing R 20 insulation levels (DOE 2008). Additionally, the wall assembly will achieve double the efficiency of the prevailing BA regional benchma rk. This value ranges from R 12 in warm climates to R 26 in cold climates (DOE 2008). Traditionally, the residential market has resisted adoption of thicker wall assemblies, hindering the potential for development and implementation of energy efficient s ystems. Thus, the subprogram will have to improve the efficiency of the wall assemblies without increasing the wall assembly thickness (DOE 2008). The strategies to achieve these goals are outlined in Table 2 3. Foundation System Goals Designing the fo undation to be more energy efficient represents the cutting edge in energy efficient home design. Consequently, the subprogram goals related to foundation development is to simply have experiments underway by 2010. The subprogram expects the importance o f thermal loss due to an inefficient foundation system to be exacerbated as gains in other system are optimized (DOE 2008).

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40 Table 2 3. Envelope subprogram wall system g oals by 2010 Envelope Subprogram Strategies for Next Generation Wall Systems by 2010 Demonstrate the next generation of exterior insulation finish systems (EIFS) Develop a non organically faced Structural Insulated Panel (SIP) Sourced from (DOE, 2008) New Materials Goals The importance of researching and developing new and innovative materials is obvious. Without material advancements the goal of NZE will be impossible to achieve. Currently, the Envelope subprogram goals for the R&D of new materials focus on field testing, durability assessment, and prototyping for market implementation (DOE 2008). The development of new envelope materials is subject to substantial barriers. The key barriers preventing implementation of energy efficient envelopes are concerns with durability, lack of technical data, and insufficient technical standards. Additionally concerns with moisture, the number one cause of envelope failure, abound as these new technologies have not yet proven themselves (DOE 2008). The goals for the development of new and innovative envel ope materials can be viewed in Table 2 4. Table 2 4. Envelope subprogram new envelope material g oals by 2010 Envelope Subprogram Strategies for Next Generation Envelope Materials Develop improved weather resistive barriers (WRBs) Develop phase change energy storage within li ghtweight building system Determine the feasibility and energy saving potential for dynamic roofing surfaces such as thermochromic materials Sourced from (DOE, 2008) Windows Within the context of BT the term, windows, is used to describe a wide range of fenestration systems. When discussing windows BT includes: combinations of glazing, sash, frames, shading elements, and other energy control features (DOE 2008, p. 252). Windows are used in virtually every building throughout the country and represent major areas of uncontrolled thermal loss and solar gain. The residential sector is responsible for 60 % of all window sales in the nation, of which the distribution is 50 % new construct ion and 50 %

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41 renovation (DOE 2008). Obviously, windows do not directly consume energy however they are responsible for 30 % of overall building heating and cooling loads, or about 4.4 quads annually (DOE 2008). Additionally, the potential to reduce light ing loads through daylighting is significant; nearly 1 quad can be saved annually (DOE 2008). Windows have the unique ability to opera te as a net energy gainer (DOE 2008). Through proper design and selection, windows can help heat a space in the winter, allow for cross ventilation, and provide daylighting. The process of selecting the ideal window for an application is difficult due to the number of variables which must be considered: such as which technology, size, application, orientation, and climate. Thus, the development and proper application of more efficient and specialized windows is essential to achieving NZE by 2020 (DOE 2008). BT approaches the problem in a unique fashion. The program states the first step is to shift windows from being are as of thermal loss, thus energy consumptive, to being energy neutral. Once this is achieved the windows should then shift to cre ate a net energy surplus, through passive he ating, cooling, and so on (DOE 2008). Essential to the development of net energy s urplus window systems is altering the role of windows from static systems to dynamic systems. Once a window system can alter its performance in accordance with the hour, season, and weather condition the role of a net provider of energy can be achieved (D OE 2008). In general, a window should reduce thermal loss in the winter, control solar gain in the summer, and provide enough daylight throughout the day (DOE 2008). Additionally, all these criteria should be met while providing a safe, affordable, durable, aesthetically pleasing, and maintainable window. A major goal of the BT R&D is to implement these, smart, dynamic window systems into the built environment (DOE 2008). The window performance goals outlined by the BT program can be viewed in Figure 28.

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42 Figure 2 8. BT windows subprogram performance g oals (DOE 2008, p. 253) The Windows R&D subprogram has four objectives: dynamic windows, highly insulated windows, enabling technology research for efficient products, and daylighting and advanced faced systems (DOE 2008). The review has briefly examine d each goal and the technologies to achieve them, as identified by BT. Dynamic Windows For dynamic windows the subprogram will attempt to develop optical switching coatings which are able to provide d ynamic control of sunlight over a broad spectrum of conditions. Additionally, the dynamic window systems will be fully integrated into building system controls, allowing for fully automated dynamic windows or remote manual access (DOE 2008). The efficien cy gains and added thermal comfort, if achieved, would be significant. The largest natural energy flow in a building is the absence and presence of sunlight. The Windows subprogram is pursuing the development of reflective hydride dynamic window (RHDW) as the solution to harness this energy (DOE 2008). The first generation of RHDWs are

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43 too small and cost prohibitive for implementation. Consequently, the subprogram is currently researching and developing the second generation of RHDWs, chemical engineer ing applications, and advanced manufacturing processes to reduce the cost and increase market penetration of these syst ems between 2010 and 2015 (DOE 2008). Highly Insulated Windows The next main goal of the subprogram, highly insulating windows, attempts to reduce heat loss rates of windows and develop high solar heat gain windows for northern climates; all the while preserving the traditional characteristics of windows (DOE 2008). When highR glazing systems are implemented in conventional window frames half of the energy lost is through the frame. Thus, the subprogram focuses on the advancement of conventional window frames via examination of: how low conductivity materials are used, the potentials of insulating voids, the use of thermal breaks in sele cted areas, suppression of radiation and convection within voids, interactions of spacers, impacts of hardware, and pr oduct design for function (DOE 2008, p. 257). In conjunction with the development of a more energy efficient window frame, the subprogr am is pursuing the development of low cost, high r value insulating glazing systems. Today, the highest performing windows in the U.S. achieve U values between 0.15 and 0.35. These levels of insulation are achieved via multiple layers of glass and gas fi lled voids, making the systems exceedingly heavy, thick, and expensive. Consequence of the significant additional cost, these systems have not had much market penetration (DOE 2008). The subprogram will address issues of weight and cost; aiming to reduc e them significantly by developing new high performing glazing systems with conventional components and manufacturing techniques, to keep incremental costs low (DOE 2008).

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44 Enabling Technology Research for Efficient Products In order to properly design, test, and rate these new dynamic systems the subprograms goal of, enabling technology research for efficient products, will develop the, tools, test facilities, and data resources needed to accurately predict component, product, and systems thermal, o ptical, daylighting, and energy performance under a full range of operating conditions (DOE 2008, p. 254). Such facilities and procedures will be necessary if market penetration of the new window systems is to be successful. The R&D teams must be able to demonstrate significant efficiency gains while preserving aesthetics, durability, and low incremental cost. Crucial to the success of this goal is the development of design tools to assist manufacturers with efficient product production (DOE 2008). In the past, the process of prototyping was costly and time consuming. Manufacturers had to physically build and test each prototype to gain accurate performance data. Today, computer modeling software allows for relatively quick and cost effective testing of new systems. These modeling programs are able to model heat transfer and solar gain through glazing and heat transfer through framing. The BT programs goal is to extend the capabilities of the available software so that parameters are easily updated to stay current or ahead of material R&D efforts (DOE 2008). Daylighting and Advanced Faade Systems Finally, the daylighting and advanced faade systems goal of the subprogram will attempt to develop technologies which will eliminate 50 to 90 % of day time electrical lighting necessary for building perimeter areas (DOE 2008). The subprogram will also effectively increase the depth which light can penetrate into a building, increasing the building perimeter area. Historically, many of the advancements in window systems have focused on thermal characteristics, typically sacrificing the optics of the systems. The BT Windows subprogram will explore technologies which can improve the transmittance of light into buildings, effectively

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45 reducing artificial lighting needs. The subprogram will also investigate and promote implementation of new technologies dedicated to natural light distribution in buildings, such as light pipes (DOE 2008). Furthermore, this goal addresses the development of innovative faade solutions which will achieve net 60 to 80 % energy and demand savings as compared to typical ASHRAE compliant faades per climate (DOE 2008). Current technologies allow for a semi dynamic building faade with computer controlled shading devices and dynam ic lighting via perimeter sensors. The Window subprogram will advance current control algorithms, create better sensors, and develop these technologies in test facilities. Moreover, new commissioning and operation strategies will be developed to optimize operational efficiency (DOE 2008). Photovoltaics (PV) While BT acknowledges PV technology as the most widely applicable onsite energy producing system, it neglects to describe the current and future state of the technology. Throughout most of the BA defined hot and humid climate region, PV energy is the only feasible source for onsite energy production. The BA program identifies onsite renewable energy production of 30 % of annual energy consumed as the target by 2020 to achieve NZEH. The review will now briefly examine the current state of PV energy production and its residential application. Currently there are two prevailing methods of implementing PV in residential buildings, building attached photovoltaics (BAPV) and building integrated photovol taics (BIPV). Building Integrated Photovoltaics BIPV are fully integrated into the building structure and are essentially permanently installed. Examples of such systems include PV shingles, tiles, slate, and metal. Furthermore, BIPV can be utilized to wholly replace building components such as windows, awnings, skylights, and roof decking systems (Barkaszi and Dunlop 2001). BIPV often employ thinfilm PV panels which can be integrated almost seamlessly with materials and thus are aesthetically

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46 more ap pealing than BAPV. On the other hand, thinfilm technology has traditionally been less efficient than its silicon wafer counterpart. In 2008 the National Renewable Energy Laboratory creating a thin film solar cell capable of converting 19.9 % of the sola r energy into useful energy, without concentrators (REW 2008). However, the average efficiency of thinfilm solar cells is about 11 % depending on installation angle and orientation. Results from a recent class laboratory assignment confirming this efficiency can be viewed in Table 2 5. Thinfilm BIPV have gained in popularity as they are able to be manufactured at a fraction of the cost of traditional silicon wafer solar cells. However, due to noted degradation of performance over time of 15 to 35 % the ir market share is a dismal 7 % Nevertheless, BIPV via thinfilm technology dominates its niche market of applications less than 50W. Combine BIPVs seamless integration and relative low cost with improved efficiency in the future, and you have a very co mpetitive alternative to traditional PV systems (Solarbuzz 2009). Table 2 5. Measured thin film BIPV efficiency, southern o rientation Elevation Solar Flux Volts Amps Power PV Power PV Collector (Degrees) (w/m 2 ) (E) (I) (EI, watts) (w/m 2 ) Efficiency 0 6 25 20.65 3.15 65.05 625 10.41% 15 840 26.83 3.57 95.78 840 11.40% 30 1115 33.27 3.99 132.75 1115 11.91% 45 1250 34.53 4.09 141.23 1250 11.30% Horizontal Solar Flux 625.00 (w/m 2 ) Building Applied Photovoltaics BAPV are considered add on systems an d are attached to the roof via a mounting system. These systems represent the conventional type of technology most people associate PV with. Consequently, this type of system has grasped 93 % of the PV market (Solarbuzz 2009). BAPV are connected firmly to the roofing system of residences via a superstructure whose feet are mechanically fastened to structural members of the roofing system. These superstructures

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47 can be separated into standoff and rack mounted array types (Barkaszi and Dunlop 2001). The m ain difference between the two systems is the angle at which the panels are oriented. Standoff BAPVs are mounted parallel to the slope of the roof, and thus, their efficiency is subject to the angle and orientation of the roof. Rack mounted arrays are ty pically used for flat roof situations and align the panels at the optimum angle and orientation for that specific location (Barkaszi and Dunlop 2001). Efficiencies for BAPV average around 16 % but vary widely; consequence of multiple types of silicon wafe r production technologies, s ite constraints, orientation, angle, and so forth (Solarbuzz 2009). Despite their large market share, BAPV via silicon wafer technologies have many disadvantages. The most obvious disadvantage is cost due to their intensive use of silicon material. Other shortcomings include thickness of the system, aesthetics, and possible shortage of solar grade silicon (Goetzberger 2005). Photovoltaic Constraints As mentioned, the performance of any PV system is highly dependent upon orientation, location, and site conditions. The single most inhibiting factor of PV cell performance is shadows. Even covering a very small % age of the collector area has proven to have significant impacts on system performance (Barkaszi and Dunlop 2001). As a result, great attention must be placed on shielding the PV system from shadows. Shadows can come from nearby buildings, flag poles, vegetation, towers, and so on. When finalizing the location for the PV system is it vital to consider future property development and tr ee growth (Barkaszi and Dunlop 2001). When installed, PV systems ideally will have unobstructed solar access from 9:00 a.m. to 3:00 p.m. (Barkaszi and Dunlop 2001). When determining the final tilt and azimuth angles it is imperative to consider the site latitude and annual energy performance desired from the system. As most PV systems tilt is limited by the pitch of the roof, the generalized rule of thumb is to orient the panels facing south, within +/ 15 degrees of your latitude (Barkaszi and Dunlop

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48 2001). Tailoring the PV tilt to suit the highest seasonal energy demand is an important consideration as well. For northern climates the majority of space conditioning occurs in the winter months, thus PV systems should be installed with higher tilt to take advantage of the low path of the winter sun. Conversely, in the hot and humid climates of the south less tilt should be applied to panels to maximize energy production during the summer months (Barkaszi and Dunlop 2001). Furthermore, mounting technique can impact the cooling and heating load necessary throughout the year. Directly mounted BAPV and BIPV can increase heat transfer between roof surfaces and conditioned space as the panels heat up during the day. This observation is most ly beneficial in northern climates and an obvious detriment in warmer climates. On the other hand, standoff systems can reduce the amount of heat transfer as they shade the roof, a good strategy for hot and humid climates (Barkaszi and Dunlop 2001). Pho tovoltaic Cost The financial feasibility of PV implementation in the residential sector is improving Installed cost per kW is, on average, about $10,000 (GLSL 2009). The cost of the onsite energy systems is, currently, highly subsidized in many areas by the state and federal government. For example, it is possible to install a 5 kW PV system on a residence in Florida for around $6,000, about $32,000 less than its nonsupplemented value. These savings are the results of the implementation of the America n R ecovery and Reinvestment Act of 2009 (ARRA). The details of the financials can be viewed in Table 2 6 (Allsolar, personal communication, May 15, 2009). Additionally, with the recent adoption of net metering and the feed in tariff in the U.S. the payba ck period for PV systems can be drastically reduced. Leading the way in promoting decentralized PV energy production, Gainesville Regional Utilities (GRU) has come up with a promising incentive for homeowners implementing PV. GRU is offering $0.32 per kW h contributed to the grid. This feed in tariff is the first in the U.S. and offers nearly 3.5 times as

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49 much per kWh sold as kWh used (Armistead 2009). The GRU program will likely spur similar incentives around the nation, making the feasibility of PV for early adopters more promising than ever. Table 2 6. Effects of the ARRA on residential PV Allsolar Residential Example Before January 1, 2009 5kW System $ 40,000 FL State Rebate 20,000 30% Tax Credit 6,000 Final Cost after incentiv es $14,000 Current ARRA 2009 5kW System $40,000 FL State Rebate 20,000 30% Tax Credit 12,000 Final Cost after incentives $6,000 Improved Disaster Resistance Weather phenomena in hot and humid climates are some of the most severe i n the nation; specifically hurricanes. An added benefit of designing NZEHs and utilizing PV for onsite energy production is the added function of a more disaster resistant building. In addition to advanced construction techniques, such as connecting the roof to the foundation, a disaster resistant building relies on renewable energy sources to provide the bare minimum amount of energy necessary to maintain the essential life supporting functions of a home in the aftermath of a d isaster (Haggard and Young 2006). Providing the added benefits of weathering the storm and thriving afterwards, represents an added benefit of NZEH design which is difficult to quantify. Regardless this, priceless life and property saving building technique is an important con sideration when building in hot and humid climate zones and consequence of the PV array installed (Haggard and Young 2006, p. 2514).

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50 Progress toward Creating NZEC: Past and Present Projects The review has briefly spotlight ed past and present attempts at creating NZECs. While none of these examples achieved NZE, their contributions to the advancement of energy efficient community design are noteworthy. As mentioned before, the equation to create NZECs is quite simple; a builder/developer designs a home w hich can achieve NZE and multiplies it to the desired community density. Ultimate feasibility of the NZEC concept relies on the selling price of a NZEH falling within said markets acceptable range; all the while providing the expected return on investment for the builder/developer. Premier Gardens Several developments implementing the above strategy have been built since 2001, and many more are currently in early conceptual phases. One of the earliest and most valuable studies in energy efficient communi ties to date is the Premier Gardens community in Sacramento, California. This project is considered to be so valuable because directly across the street a similar community was built by a similar builder without any energy e fficient features, resulting in a apples to apples comparison. Premier Gardens is comprised of 95 entry level homes varying in size between 1280 and 2250 square feet (Parker 2009). These homes were designed and built to very moderate levels of energy efficiency as described by Parker (2009, p. 515): RSI 6.8 (roughly R 40) ceiling insulation and RSI 2.33.4 (about R 13 to R 19) wall insulation, tankless gas water heaters, high efficiency gas furnaces, tightly sealed ducts buried in the attic insulation, fluorescent lighting in all permanent fixtures. Furthermore, each home was equipped with its own 2.2 kW PV array. The Sacramento Municipal Utilities District (SMUD) monitored both communities and concluded that the Premier homes averaged, 34% lower gas consumption and 16% lower elect ricity use without solar power production being considered. With the PV included, the homes averaged 54% lower electrical demand particularly evident

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51 during summer peak periods (Parker 2009, p. 515). SMUD continued to monitor the homes in the development for a year which resulted in an average energy consumption of 70.1 kWh/m2; this figure is less than half of what an average SMUD home consumes, about 144 kWh/m2 (Parker 2009). Consequently, the Premier homes community demonstrated a 50 % reduction in ene rgy use at an average incremental cost of $18,836 without factoring in California specific rebates (Parker 2009). Other Builder/Developer Attempts Due to the relative success of the Premier homes project, three other builders in California and one in Ari zona have mimicked the concept. The builders in California are Shea Homes, Clarum Homes, and Grupe Homes; the one in Arizona is John Wesley Miller (Parker 2009). Shea Homes has monitored their projects and have averaged a 54 % reduction in energy consumption, as compared to their traditional homes. A huge marketing tool for these builders is the significant reduction in the homeowners monthly utility bill. The average utility bill for Armory Park del Sol, the John Wesley Miller community, is $16/month (Parker 2009). Additionally, all three California builders have said the near zero energy homes sell much more quickly than a conventional home. At Grupe Homes community Carsten Crossings, the energy efficient homes were selling twice as quickly as the competitions homes. Therefore the builder has stated a savings of $13 million in overhead (Parker 2009). With such compelling historical evidence it is difficult to imagine the decline of the NZEC concept Gainesville, Florida: NZEC Prospect The NZEC conc ept is currently under development in the hot and humid climate zone. As mentioned, this type of climate represents a significant challenge in achieving reductions in energy consumption due to the existence of large cooling loads. Gainesville, Florida, a n oasis in the desert that is the hot and humid climate zone, is a front runner in energy efficient home

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52 design for the climate zone; implementing the first energy star homes, near zero energy homes, and soon to be one of the first NZEHs in the area. Gai nesville is the home to multiple BA program builders and developers: Atlantic Design and Construction, G.W. Robinson, Richard Schackow, and Tommy Williams Homes to name a few (Baechler and Love 2004). Consequence of the improved energ y performance of the homes, G.W. Robinson targets a 10 % return on investment. The builder has no problem attaining these figures as homeowners are given 1/8 point discounted mortgage rates and are approved for higher priced homes due to the expected lower monthly utility bill (Baechler and Love 2004). The next major advancement for energy efficient homes in the hot and humid climate zone is under development by local builder Tommy Williams Homes. The builder is currently working in conjunction with BA and FSEC professionals to design and build the first true NZEH in the hot and humid climate zone; the home will be in the emerging Long Leaf development. If successful, the home will provide the builder with the solution to the NZE equation, possibly elevating Long Leaf to the status of the first true NZEC in the nation. The Business Case for the Development of NZEC s The final part of this review focus ed on the business case for implementing sustainable ideas in the built environment at the corporate level. The review will t ake a large step back and examine the environmental, social, and economic reasons to adopt sustainable practices at all scales By examining the impacts of sustainable practices at the broadest level the review will indirectly identify why todays builders /developers need to adopt this mentality to not only turn a profit, but make the NZEC concept a reality. Total buy in from all scales of economic and social stakeholders is essential if the NZEC concept is to be a success. A shift in the corporate mindse t is on the horizon. Business leaders around the world recognize that sustainability has moved beyond the corporate social responsibility agenda to

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53 become an integral part of core business strategy and success (of a business) (Bent 2008). Companies are moving away from asking; how do we integrate a sustainability plan into our business? Towards; how do we develop a business strategy from our susta inability plan (Bent 2008)? The biggest obstacle to these types of corporate changes is the lack of a stron g business case for operating sustainably. Multiple entities around the world strive to provide these forward looking businesses with compelling arguments for the adoption of a sustainable development plan. The World Business Council for Sustainable Development (WBCSD) is one such entity. The WBCSD is a coalition of 160 international companies who share in their commitment to sustainable development via the three pillars of economic growth, ecological balance, and social progress (WBCSD 2002). The WBCS D defines sustainable development as, forms of progress that meet the needs of the present without compromising the ability of future generation s to meet their needs (WBCSD 2002). Simply put sustainable development is about ensuring a better quality of life for everyone, now and for generations to come. This umbrella term, sustainable development, is anchored by the three overarching subsections: social, environmental, and economical responsibility. The WBSCD argues that the execution of all three cr iteria, while maintaining a profit, will define the successful business of the future (WBCSD 2002). So, how does the business case for sustainable development relate to the built environment and the NZEC concept ? Simply put, every business has a physical building which contributes to the glutton that is the built environment. The business case for sustainability in the built environment mirrors that of the WBCSD. Buildings and infrastructure which take into consideration social, environmental, and economic concerns will outperform and outlast those which do not. The

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54 ultimate acceptance of sustainable development in the built environment is exacerbated by the magnitude of the impacts it has on the environment and society. The Built Environment consumes 30% of all primary energy in the United States. The associated burden (extracting, processing, transporting) of gathering the energy necessary to satiate this high demand belongs to the Built Environment as well. Additionally, the sprawling unchecked gro wth of the Built Environment has led to increased dependency on automobiles. The Built Environment consumes 40% of all materials annually extracted in the United States, and contains nearly 90% of all materials historically extracted (Kibert 2002). Clear ly there is room to improve. This section highlight ed the business case for reducing the impacts of the built environment from an economical perspective. However, it is important to note that most of these economic benefits also pay dividends in social a nd environmental capacities as well. The business case for sustainability in the built environment is based on a framework of benefits: economic, productivity, risk management, health, public relations and marketing, recruitment and r etention, and fundin g (Yudelson 2008). The arguments which provide the most compelling evidence for acceptance by stakeholders are the economical indicators. One economical benefit of sustainably built buildings is that they generally operate using 25 to 40 % less energy th an comparable code compliant buildings. This reduction in energy use translates to between 40 cents and $1 savings per square foot of electricity us e (Yudelson 2008). These savings come with an additional cost averaging between 1 and 2 % of capital costs with a relatively short payback period (averaging less than three years). To quantify these savings in energy costs, an 80,000 square foot building would save between $32,000 and $80,000 per year, year after year, at todays prices (Yudelson 2008).

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55 A nother advantage of building Green is an overall reduction in operational and maintenance (O&M) costs. According to Jerry Yudelson, Chair of the 2008 Greenbuild International Conference and Expo: More than 120 studies have documented that energy saving buildings that are commissioned properly at 50 cents to $1 per square foot of initial cost (equal to one year of savings) show additional operational savings of 10 to 15 % (and) tend to be much easier to operate and maintain (Yudelson 2008). These savi ngs in O&M costs are a result of comprehensive functional testing of all energy using systems prior to occupancy. Additionally, these testing measures identify potential problems prior to final turnover. As a result of the energy savings and lower O&M co sts the overall value of the building increases (Yudelson 2008). To illustrate this principal lets consider a 75,000 square foot commercial building that saves $37,500 per year. With a capitalization rate of 6 % the building would gain $625,000 in value as a result of Green practices (Yudelson 2008). If a builder/developer were to act as the owner for their first NZEC, renting out the units, one could imagine the amount of savings to be had based upon the figures above. Tax benefits offer further incen tive to build Green. Some states, such as Oregon and New York, and Florida offer state tax credits. Other states, like Nevada, offer property and sales tax abatements for building Green. On top of these state tax credits, the federal government can hel p offset the initial Green investment with their own tax credits (Yudelson 2008). For example, Oregons tax credit is dependent on two variables; building area and Leadership in Energy and Environmental Design (LEED) certification level. A 100,000 square foot, Platinum Level, building in Oregon will receive a net present value tax credit of about $2 per square foot (Yudelson 2008). In Nevada, if your building achieves LEED Silver level you are allotted a property tax abatement of up to 50 % for a period up to 10 years. Assuming the property tax is 1 % of value, the abatement could be worth up to 5 % of the building cost. This would be much

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56 less than the cost to achieve LEED silver certification (Yudelson 2008). In 2005 the Federal Government passed the Energy Policy Act which offers two major tax incentives for Green buildings. According to Yudelson, a tax credit of 30 % on both solar thermal and electric systems and a tax deduction of up to $1.80 per square foot for projects that reduce energy by 50 % compared to 2001 baselines (Yudelson 2008). As illustrated, the economical arguments for sustainability in the built environment are plentiful. The above examples demonstrate only a few areas where building Green makes green. The built environment exists in many scales, ranging from the individual residence to the roads which stitch states and countries together. The next section will document ed the business case for sustainability in the built environment through a variety of these scales. The r eview examine d case studies which demonstrated the benefits discussed above at the scale of: the material supplier, individual residence, and corporate level. Material suppliers are the backbone to the Green building movement. Without sustainably produce d/oriented materials and equipment the notion of a Green building would remain a mere concept. The exponential increase in sustainable material suppliers and options is evidence of the profitability of being label ed Green. While the amount of green w ashi ng on the market can be nauseating, two companies who continue to set the industry standard are Steelcase Furniture and Interface Carpet. Steelcases director of global environmental performance, David Rinard, summarizes the companys outlook on their res ponsibility as a material supplier; If we buy a raw resource and dont turn it into product, we have an opportunity to improve (Quinn 2007). In 2004 Steelcase received the first Cradle to Cradle (C2C) certification for office furniture with its Think Cha ir (Quinn 2007). Since then the company has continued to pursue production facilities. Steelcase built the first LEED certified manufacturing plant and got eight

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57 of its global manufacturing operation ISO 14001 certified. These efforts have resulted in r eductions in a variety of e co metrics. The primary benefits resulting from Steelcases Green efforts is increased marketability, and a well justified premium on their products. Interface Carpets has set the steep goal of becoming a zero impact organizat ion by the year 2020 (Hilgers 2008). The company made this transition, after inquiries about the sustainable nature of their product from the sales floor made their way to Ray Anderson, CEO. Andersons perspective was, That piece of business was slipping away our customers care, so we have to care (Hilgers 2008). Interface has strived to create new and innovative way to recycle carpet nylon. Sabi, one of the companys carpet lines boasts 51 % recycled content, while Terratex is made of 100 % recycle d or renewable fibers. By recycling rather than wasting, Interface has saved $372 million in waste reduction alone (Hilgers 2008). Anderson contributes his companys success to their 100 % buy in to sustainable practices; No amount of advertising could have brought us this much goodwill I have never known a more powerful differentiator than sustainability (Hilgers 2008). Next, the review will examine the business case for sustainability at the scale of the private residence. Building Green at the sca le of a private residence is likely the most difficult scenario to sell. Homeowners lack the capital of large corporations, and might not live in the same residence long enough to fully capitalize on any energy saving systems. However, homeowners are typ ically more receptive of and subject t o the same benefits discussed above A shining example of the potential for savings in a residence is the Z6 house in Santa Monica, CA. The Z6 house served as a prototype for LEED for Homes v.1 and ended up achieving Platinum level certification (Building Green 2007). Z6 stands for the, six zeros, or the design goal for the house: zero waste, zero energy, zero water, zero carbon, zero emissions, and zero ignorance

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58 (Building Green 2007). Financially, it is pretty clear how achieving the six zeros would benefit a homeowner. Highlights of the home include: a 3500 gallon cistern, a 2.4 KW photovoltaic array w/ battery storage, LED lighting, Pre manufactured and assembled onsite, and an indoor garden (Building Green 2007). These systems work together to make the z6 home 80 % more energy efficient than a conventional comparable home, all the while producing 75 % less construction waste (Hanes 2007). It is clear that the z6 home will benefit from a higher resale value, lower operating cost, longer life span, multiple tax breaks, and unparalleled energy cost savings. These savings and benefits, realized at the scale of an individual home, are exponentially increased at the scale of a community Paul Hawken, often descri bed as the father of sustainability, generalized the hurdles which plague all corporations: Business has three basic issues to face: what it takes, what it makes and w hat it wastes. First, business takes too much from the environment and does so in a harm ful way. Second, the products it makes require excessive amounts of energy, toxins and pollutants; and finally, the method of manufacture and the very products themselves produce extraordinary waste and cause harm to present and future generations of all s pecies, including humans (Freese 2007). By reducing impacts in these three areas companies can reap the economic benefits discussed. A prime example for the business case of sustainability in the built environment of corporations involves Ford Motor Com pany. The architect in charge of the renovation of Fords WWII era River Rouge Factory was William McDonough. McDonough says, The key to getting businesses to go green is to make the sustainable technology so profitable that the const conscious executiv es cant afford not to change (Fainelli 2001). The centerpiece of his overhaul at the factory was a 454,000 square foot green roof, complete with native foliage. This simple gesture resulted in a savings of nearly $35 million worth of stormwater treatment per year (Fainelli 2001).

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59 DuPont CEO, Chad Holliday, believes sustainability is good for business to the tune of $6 billion (Johnson 2006). DuPont plans on achieving this through sustainable market offerings, but primarily through revamping industri al processes, Greening production facilities, and converting their global fleet of automobiles to the most efficient system available by 2015 (Johnson 2006). Armstrong World Industries, Inc. is a global leader in the design and manufacture of floors, cei lings, and cabinets for residential and commercial buildings (Eberly 2007). Armstrong takes pride in its environmental position highlighted by ecofriendly product offerings and multiple corporate sustainability programs. In 2006 Armstrong made the decis ion to revamp their corporate headquarters in Lancaster, Pennsylvania according to LEED EB standards. In the end, Armstrong achieved a LEED EB Platinum level, making their headquarters one of only five LEED EB Platinum buildings (2007 statistic) (Eberly 2007). The original building was designed and built in 1998 with extensive Green methodologies which helped to keep costs of LEED EB renovation down. In the end the total out of pocket cost to bring the headquarters up to Platinum levels was $138,000 (Ebe rly 2007). From these efforts Armstrong was able to: save about $25,000 annually in energy costs, save $4,400 annually on cleaning and maintenance products, and save 380,000 gal of water annually to name only a few of the economic benefits (Eberly 2007). The review has examined on a broad scale the economic benefits resulting from Green building practices: reduced energy costs, reduced O&M costs, tax breaks, and increased building value and marketability. All of these benefits are directly applicable to the builders/developers who pursue NZEC. The review has demonstrated how said benefits manifest themselves at the scale of the material supplier, the residence, and the corporation. The business case for

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60 sustainability in the built environment is clear, building Green makes green. However, it is the additional concerns (social and environmental) linked with these economic benefits which are difficult to identify and quantify. The next step in the overall sustainable development movement is to build the business case for social and environmental consideration by all businesses. The successful business of the future will be one which address all three issues of sustainability on equal terms, and does so while generating a profit. Furthermore, the ideal vehicle for builders/developers to achieve these lofty conditions is the NZEC concept.

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61 CHAPTER 3 METHODOLOGY This chapter outlined the process which was followed to address the thesis statement. This thesis examined the feasibility of developing net ze ro energy communities in hot and humid climates. Feasibility was determined against the calculated average single family new home cost per square foot to construct in Gainesville, Florida. Additionally, this study focused on the problem statement from th e perspective of the builder/developer. Accordingly, the advantages to the builder/developer were identified. A detailed synopsis of the analytical steps taken follows. Step 1: Literature Review A literature review was condu cted and focused heavily on the DOE Building Technology (BT) and Building America (BA) programs. Within these programs the review identified the current state of energy efficient home design and examined the future goals of the program; essentially the objective s which must be met if the program is to achieve its intention of NZEHs by 2020. Furthermore, the literature review examined technologies outside the scope of BA which could be implemented to increase the energy efficiency in homes. Step 2: Determine Gainesvilles Baseline Cost /SF The next step determine d the baseline cost per square foot for a new singlefamily home built in a community of Gainesville, Florida. Seide (2009) reports that the average price per sf for new construction of single family homes in Gainesville is curr ently $147. To validate this figure, this work calculated its own baseline cost from readily available information. When determining the baseline cost per square foot BA partner homes were separated from conventional single family homes built in communities. The results indicate that the BA builders /developers are able to deliver a higher performing home at the same cost per s quare f oot on average. The conventional homes cost per s quare f oot to construct was calculated

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62 directly from availabl e new homes listing prices and published square f oot of living space. The determined average cost per s quare f oot to construct a new single family home in Gainesville, Florida was then multiplied by 1500 s quare f oot This size was determined to be the average size of a single family home in Gainesville through an interview with local developer Richard Schackow (personal communication, June 12, 2009). The resulting values were a baseline cost of $146 per s quare f oot and $219,000. The raw data can be viewed in Table 31. Table 3 1. Cost per sf to construct a new single family h ome including l and Non BA Partner Homes 1 Square Foot Listing Price Cost per Square Foot 1 2939 $399,900 $136 2 1577 $243,760 $155 3 1600 $258,000 $161 4 1533 $238,561 $156 5 1845 $263 ,324 $143 6 1553 $235,747 $152 7 1553 $242,236 $156 8 1533 $245,718 $160 9 2914 $382,000 $131 10 1452 $179,900 $124 11 1350 $172,900 $128 12 1235 $171,900 $139 13 1529 $173,900 $114 14 1478 $165,000 $112 15 1245 $159,900 $128 16 1526 $225,000 $1 47 17 2223 $351,500 $158 18 2136 $367,500 $172 19 1749 $253,000 $145 20 2714 $325,000 $120 21 1692 $239,000 $141 22 1600 $259,675 $162 23 1857 $287,985 $155 24 1653 $263,740 $160 25 3159 $578,000 $183 Average $146 BA Partner Homes Tommy Wi lliams 1,508 $216,492 $144 Tommy Williams 1,542 $226,405 $147 Tommy Williams 1,508 $229,200 $152 Tommy Williams 1,802 $263,706 $146 Tommy Williams 1,919 $284,900 $148 Tommy Wi lliams 3,045 $399,400 $131 G.W. Robinson $165 Richard Schackow $134 Average $146 Gainesville Baseline Home First Cost to Homebuyer $219,000 1 Information gathered from: (Hartley, 2009);(Bosshardt, 2009);(Homes,2009);(Trulia, 20 09)

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63 Step 3: Identify the Builder/Developers Advantages & Goals This work then identified the builders/developers advantages and subsequent goals of building energy efficient homes. The builder/developer goals were identified through correspondence and interviews with local builders/developers of energy efficient communities, and a BA case study of local builder G.W. Robinson Builders (McIlvaine et al 2008). Builder/Developer Advantages In todays lean economy it is imperative that a builder/developer maintain a competitive advantage in the marketplace. As the societal buy in of a sustainable lifestyle grows, many consumers are demanding more from themselves and the things they purchase. The single most significant purchase for any individual, their home, is no exception. Consumers are demanding higher efficiency, a healthier indoor environment, and less environmental impact; all the while maintaining conventional aesthetics and cost. Consequently, many of todays leading builders/developers have identified energy efficient, sustainable homes and communities as the key to the future success of their business. There are documented advantages to developing sustainable, energy efficient communities. To begin with, energy efficient communities enjo y fast tracked permitting and approvals from local and state governments. In Delaware, if a builder/developer conforms to the new Super Green program for the development of land and infrastructure (read community) they can shave up to two years off the average planned unit development application process (Binsacca 2009). Due to the often repetitive, prescriptive nature of residential communities the builder/developer has a unique ability to control the economies of scale for materials and labor. By repli cating only a few home styles, the builder/developer eliminates the learning curve associated with unique homes and is able to buy materials in bulk at lower costs. Green builder/developer CJ Crowell supports this notion by

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64 saying, Well certainly be abl e to lower hard costs with the type of hom e and the volume were building (Binsacca 2009, p. 2). Furthermore, builders/developers of green communities benefit from a better public image. Another major advantage for builders/developers is greater market ability and higher than average unit sales. G.W. Robinson of Gainesville, Florida is a BA partner and regularly advertises the fact. G.W. Robinson has been building energy efficient homes in the area since 2000 with a sales price range of $300,000 up to $1,000,000; averaging $165 per square foot (McIlvaine et al. 2008). The local market has responded to the extra efforts of the builder as G.W. Robinson enjoys stronger sales in their CobbleField development at a lower comparable cost to the homeowner. Additionally, the builder/developer enjoyed higher than average home sales at the beginning of the residential market downturn in 2006. G.W. Robinson closed 91 homes in 2005 and 96 in the tough market of 2006 (McIlvaine et al. 2008). The builder/develope r planned the CobbleField development in Gainesville to BA Best Practices standards. The community was one of the first to achieve a 40 % reduction in average energy consumption at very low incremental cost to the homeowner, acting as a pilot community fo r the 2010 BA Best Practices (McIlvaine et al. 2008). Builder/Developer Goals The overall goal of any builder/developer is not so complicated to define. Ultimately, the builder/developer is in the business to make money. The advantages outlined above make a compelling argument for building the first NZEC. Additionally, it has been demonstrated that building green makes green. However, the risk accompanied with the additional costs and relative novelty of the concept is significant. Consequently, it is likely that anyone who invests in the development of the first true NZEC will expect a higher than average return on investment. This fact represents a major hurdle for the financial feasibility of NZECs. However, as local developer Richard Schakow pointed out in an interview, it is very important to consider

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65 the culture of the area which you build (personal communication, June 12, 2009). Schackow highlighted the areas desire and acceptance of energy efficient homes, concluding that it could have a significant impact on the feasibility of NZECs regardless of incremental cost. Step 4: Energy 10 Development This work then identified/quantified the modeling and building parameters for Energy 10. Energy 10 is an energy modeling software created by the National Renewable Energy Laboratory (NREL) and funded by the U.S. DOE. The software is exclusively distributed through the Sustainable Buildings Industry Council (SBIC). The version used for this thesis was v1.8 which includes the ability to accurately size and model PV and Solar DHW systems. The validity of any energy outputs is a direct reflection of the accuracy of information inputted. Subsequently, a significant amount of time and energy was devoted to identifying a scientific framework for modeli ng the homes and converting the system values to their appropriate metrics. Load Profiles The BA 2008 Benchmark (Hendron 2008) was consulted to develop the appropriate load profiles for each of the Energy 10 internal gains. These internal gain load profiles define, on a 24 hr timescale, the % age of peak energy consumption for a given domestic system. There are a total of five profiles, each of which has two operating modes; workday and nonworkday. The five profiles which were defined relate to intern al lights, external lights, people number, hot water, and other (MELs). For the sake of this work, a typical work week of 95, Monday through Friday was assumed. Energy 10 does not allow for as detailed a modeling scenario as the BA 2008 Benchmark outline s. Areas which Energy 10 is lacking are the modeling of individual major appliances and detailed domestic hot water usage. Additionally, the metric for which these systems are measured is difficult to quantify accurately. The unit used in Energ y 10

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66 for most load profiles is w atts per square foot (W/ft2). Consequently, for the load profiles for domestic hot water and MELs the energy efficiency gains were determined by quantifying the average energy savings of the efficiency measures and multiplying the E nergy 10 baseline value by the appropriate reduction in energy. For example, the average reduction when using Energy Star appliances versus conventional ones is roughly 30 % ; the baseline value for MELs in Energy 10 is .36 W/ft2, therefore the reduction i n load would be 30 % of .36 W/ft2, or .252 W/ft2. Additionally, Table 17 of the BA 2008 Benchmark provides a comprehensive list of residential appliances and their annual kWh consumed. This table was consulted to determine the reduction in MELs for the B A 2008 Best Practices home and NZEH. Lighting Load reduction related to changes in lighting type was calculated. The different lighting systems implemented were incandescent, compact fluorescent and solid state lighting (SSL); also known as light emitting diodes (LEDs). The modeled reductions in energy consumption, as compared to the baseline incandescent bulb, are identified in Table 32. Table 3 2. Energy efficiency of l ightin g f ixtures Baseline Lumens/Watt Lumens @ 40w Incandescent 14 560 EE Type Lumens/Watt Watts to Equal Baseline Efficiency CFL 60 9.33 76.67 SSL 80 7.00 82.50 Sourced from (Green 2009) a nd (DOE 2008) Unit Conversion Other metrics used in Energy 10 are not the most widely advertised units. Most HVAC systems are advertised using the Seasonal Energy Efficiency Rating (SEER), Energy 10 requires the efficiency of the HVAC system be express ed as Energy Efficiency Rating (EER). The BA 2008 Benchmark provides an equation for converting SEER to EER. This equation was used and is as follows: EER = 0.02 x SEER2 + 1.12 x SEER (Hendron 2008). Another example of

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67 metric mismatching relates to the tightness of the building. The metric used to determine the tightness of homes is Air Changes per Hour at 50 Pascals (ACH50). This test is performed after a residence is built and is commonly referred to as blower door testing. Energy 10 addresses inf iltration with the Air Changes per Hour (ACH) metric. The values used for the Energy 10 models were derived from two sources; the Gainesville Baseline was assigned an ACH50 value of 6 and the BA Best Practices a value of 4.5 (McIlvaine et al. 2008); the N ZEH homes infiltration value was determined to be ACH50 of 2 (Icynene 2008). The significant reduction in ACH50 is consequence of the Icynene wall insulation system employed. Icynene is a water based, spray on open cell foam insulation. It has the unique ability to expand within the wall cavity creating the tightest of envelopes. As discussed, the ACH50 values were converted to ACH so they could be accurately calculated in Energy 10. The conversion factor for ACH50 to ACH used was: ACH = ACH50/20 (Home Energy 2009). Operating Conditions Operating conditions for the energy models were derived from BA 2008 Benchmark guidelines. The thermostat set point was compliant with the American Society of Heating, Refrigeration, and Air Conditioning Engineers (AS HRAE) Standard 551992. The BA Benchmark identifies these values as 76 degrees Fahrenheit for cooling and 71 degrees Fahrenheit for heating with no setup/setback period. In the case of the NZEH a setup/setback was used. The number of occupants was deter mined using the equation: Number of occupants = 0.5 x Number of Bedrooms +1.5 (Hendron 2008). Step 5: Develop the Gainesville Baseline Home in Energy 10 This work then developed the Gainesville baseline home in Energy 10. The Gainesville baseline home has been modeled to closely match the typified construction materials and methods used in the average home in the study area. The inputs were derived from a

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68 combination of communication with local builders/developers and the baseline as defined by McIlvai ne et al. (2008). The typical home in Gainesville is built slightly more energy efficient than the U.S. average. The HERS Index was developed by the Residential Energy Services Network (RESNET) and is a common rating system for energy efficient residences. The HERS baseline home scores a 100 while a NZEH scores a 0. Each point below 100 represents a single point increase in efficiency as compared to the HERS baseline. The average home in Gainesville is built to a HERS Index rating of 97 (McIlvaine et a l. 2008). The as modeled building characteristics for the Gainesville Baseline home can be viewed in Table 3 3. Table 3 3. Gainesville baseline c haracteristics Thermal Envelope Windows Double-Pane Aluminum Wall Insulation Fiberglass Batt, R-11 Ceiling Insulation R-30 Fiberglass Envelope and Duct Sealing/ACH None/0.3 Wall Framing System Standard 2x4 HVAC System Heating System 80% Gas Capacity 100Kbtu Cooling System SEER 13/EER 11.2 Capacity 5 tons Setup/Setback None Duct Leakage 6% to out Economizer Cycle None Domestic Hot Water Water Heater Efficiency (Gas) 60% Lighting General Lighting Incandescent Step 6: Develop the BA Best Practices Home i n Energy 10 This work then developed the BA 2004 Best Practices home in Energy 10. The BA 2004 Best Practices identifies targeted reductions in baseline energy use of 30 % (Baechler 2005). The BA Best Practices energy model was developing through correspondence with local BA builders/developers, the BA Best Practices for Hot and Humid Climates (Baechler, 2005), the

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69 BA 2008 Benchmark (Hendron 2008), the BT overview (DOE 2008), and the case study by McIlvaine et al. (2008). The Energy 10 inputs for the BA Best Practices energy model can be viewed in Table 3 4. Table 3 4. BA best practices c haracteristics Thermal Envelope Windows Double-Pane Vinyl Low E Wall Insulation Fiberglass Batt, R-13 Ceiling Insulation R-30 Fiberglass Envelope and Duct Sealing/ACH Mastic and Caulk/0.2 Wall Framing System Standard 2x4 HVAC System Heating System 93% Gas Capacity 60Kbtu Cooling System SEER 14/EER 11.8 Capacity 3.5 tons Setup/Setback None Duct Leakage 4% to out Economizer Cycle None Domestic Hot Water Water Heater Efficiency (Gas) 83% tankless Lighting General Lighting Full CFL Step 7: Develop the NZEH in Energy 10 This work then developed the NZEH in Energy 10. The NZEH was developed to the future g oals of the BA program. Thus, the energy model was designed to achieve a 70 % reduction in baseline energy use. The PV system was sized to accommodate the excess energy consumed, the residual 30 % with PVWATTS v1 software. In addition to the future goa ls of the BA program, correspondence with local Near Zero Energy Home developer Richard Schackow and the associated Florida Solar Energy Center (FSEC 2009) case study of the home aided in identifying the Energy 10 inputs. Sizing of the solar thermal DHW ( SDHW) system was performed in Energy 10 using their automated EE strategies. The specified target fraction of hot water load to be met by the SDHW system was set at 80 % A reduction of 50 % in MELs was applied based on the replacement of all applicable appliances with Energy Star rated

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70 replacements, removal of a clothes dryer, and assumed occupant commitment to an energy efficient lifestyle. An automated lighting system was applied via the EE strategies in Energy 10. Subsequently, daylighting evaluation was considered in the energy modeling of the NZEH. The Energy 10 inputs for the NZEH can be viewed in Table 35. Table 3 5. NZEH c haracteristics Thermal Envelope Windows Double-Pane Vinyl Low E Wall Insulation Icynene 5.5" R-23 Ceiling Insulation R-60 Fiberglass Envelope and Duct Sealing/ACH Mastic and Caulk/ 0.1 Wall Framing System 2 x 6 @ 24" O.C. HVAC System Heating System 95% Gas Capacity 12Kbtu Cooling System SEER 19/EER 14.1 Capacity 2 tons Setup/Setback Yes, 66 F and 81 F Duct Leakage 2% to out Economizer Cycle None Domestic Hot Water Water Heater Efficiency (Gas) 80% Solar Thermal DHW Lighting General Lighting Full SSL (LED) Automated Lighting Controls Yes, Perimeter Rooms Appliances Energy Star Appliances Yes, All Applicable Photovoltaic System 7 kW DC, Installed, $8k per kW Yes Step 8: Determine Averages Annual Energy Consumption This work then determine d ea ch energy models average annual onsite energy consumption. Each energy model was run four times, once for each cardinal direction. The average for each of the schemes was calculated. The average for each respective scheme is the number which the baseline and subsequent energy reductions were calculated from/against. In the case of the NZEH the onsite PV system was sized accordingly using PV WATTS v1. The system inputs for the PVW ATTS v1 PV simulations can be viewed in Table 36. Once the

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71 necessary arra y size was determined, the array was simulated in all four cardinal directions. The average of the four values was calculated and used. These measures were implemented to address the issue of non ideal building orientation in communities. Each of the e nergy efficient schemes, BA Best Practices and NZEH, were eva luated against the Gainesville B aseline. Graphical, as well as written parameter, analysis was conducted to confirm the targeted energy reductions were met with the employed energy efficient imp rovements. Table 3 6. PVWATTS v1 i nputs City: Jacksonville State: FL Latitude: 30.50 N Longitude: 81.70 W Elevation: 9 m DC Rating: 7.0 kW DC to AC Derate Factor: 0.75 AC Rating: 5.2 kW Array Type: Fixed Tilt Array Tilt: 30.0 Array Azimuth: Varies Cost of Electricity: 12.0 /kWh Station Identification PV System Specifications Energy Specifications Step 9: Quantify the Incremental Costs This work then identified the incremental cost of the energy efficient schemes. Incremental cost information was gathered in a variety of ways. Information regarding the incremental cost for the BA B est Practices was primarily sourced from McIlvaine et al. (2008). Any cost information which was to still be determined was done so using RS Means Costworks. Costworks is an online version of the RS Means Construction Cost Data book. The NZEH incremental costs were primarily sourced from the FSEC report (2009). Furthermore some of the newer efficiency measure costs, like the Icynene insulation, were sourced directly from the products respective ret ailers through personal communications Each incremental cost was

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72 converted to the subsequent amortized annual cost to the homeowner and incremental cost per square foot to construct. Builder/developer markup of 10 % was factored in. The overall incremental cost, amortized annual cost, and cost per square foot to construct to the builder/developer and homebuyer was determined. Step 10: Determine Feasibility This work then determine d feasibility of the NZEC concept from the perspective of the builder/developer. Feasibility was determined based on cost per square foot to construct to the homebuyer, and whether or not the respective figures were within the acceptable market range. The analysis was conducted in two stages; the first considering the raw cos t to the homebuyer, the second stage accounting for state and federal rebates available to new singlefamily homebuyers. Limitations to the applicability of the rebates and incentives were discussed. A summary was provided, conclusions formed, limitation s discussed, and recommendations made.

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73 CHAPTER 4 DATA ANALYSIS AND RE SULTS This section of the thesis present s the findings from the energy modeling, PV sizing, and incremental cost exercises. The energy models have been compared as follows: Gainesville baseline versus BA Best Practices and Gainesville baseline versus NZEH. Information for each scheme has been presented graphically and the detailed Energy 10 inputs/outputs can be viewed in the respective appendices. The results from the PVW ATTS v1 exer cise have been averaged and graphically represented. The incremental cost exercise compared the two energy efficient homes to the Gainesville baseline and identified incremental cost, annual amortized cost, and increase in cost per square foot to construc t. Gainesville Baseline versus BA Best Practices The typical Gainesville residence was modeled in Energy 10 and simulated against the BA 2004 Best Practices Each of the two schemes was modeled in each of the cardinal directions and the average annual en ergy consumption (kWh) wa s determined. The Gainesville B aseline consumed an average of 22475 kWh through the course of a year. The Energy 10 results for the Gainesville Baseline can be viewed in Table 4 1. Table 4 1. Gainesville baseline Energy 10 r esu lts Orientation (Degrees) (kbtu) (kWh) 0 76677 22466 90 76551 22429 180 76863 22521 270 76738 22484 Average 76707 22475 Annual Energy Use The BA B est Practices consumed an average of 15658 kWh through the course of a year. The Energy 10 results for the BA Be st Practices can be viewed in Table 4 2. The BA B est Practices resulted in a 30.33 % reduction in ener gy use as compared to the Gainesville B aseline.

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74 Table 4 2. BA be st p ractices Energy 10 r esults Orientation (Degrees) (kbtu) (kWh) 0 53466 15665 90 53327 15625 180 53523 15682 270 53449 15660 Average 53441 15658 Baseline Reduction, % Annual Energy Use 30.33 A comparative bar chart of the annual energy output for the two homes has been generated. The bar chart reports on annual heating, cooling, light, other, and total loads in the metric of kWh/ft2. The bar chart represents the average of the Energy 10 results for the four cardinal direction simulations and can be seen in Figure 4 1. The Gainesville baseline homes uses 14.98 kWh/ft2 w hereas the BA Best Practices home uses 10.44 kWh/ft2. The detailed inputs/outputs to Energy 10 and the raw data used to generate the averaged annual energy use bar chart can be viewed in Appendix A. Figure 4 1. Gainesville baseline v. BA best practices averaged annual energy use

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75 Gainesville Baseline versus NZEH The NZEH consumed an average of 6762 kWh through the course of a year. The Energy 10 results for the NZEH can be viewed in Table 4 3. The NZEH resulted in a 69.91 % reduction in energy use as compared to the Gainesville B aseline. Table 4 3. NZEH Energy 10 r esults Orientation(Degrees) (kbtu) (kWh) 0 23172 6789 90 22898 6709 180 23025 6746 270 23217 6803 Average 23078 6762 Baseline Reduction, % Annual Energy Use 69.91 The averaged results for this scheme were analyzed in the same met hod as above. The Gainesville B aseline homes uses 14.98 kWh/ft2 whereas the NZE H uses 4.50 kWh/ft2. The bar chart represents the average of the Energy 10 results for the four cardinal direction simulations and can be seen in Figure 4 2. The detailed inputs/outputs to Energy 10 and the raw data used to generate the averaged annual energy use bar chart can be viewed in Appendix B. Figure 4 2. Gainesville baseline v. NZEH averaged annual energy use

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76 Photovoltaic Sizing As indicated above, the NZEH reduced the averaged annual energy consumption to 6762 kWh per year. The PV array for th e NZEH was designed in PVWATTS v1 to accommodate this yearly load. The array was simulated in all four cardinal directions and the averaged annual energy production can be viewed in Table 4 4. The PV array was determined to have a generating capacity of 7 kW DC and produces an averaged value of 7236 kWh per year. Subsequently, the PV array will generate an averaged excess of 474 kWh per year. The detailed simulation results from PVWATTS v1 can be viewed in Appendix C. Table 4 4. Averaged PVWATTS v1 Simu lation Data, 7 kW DC Month (kWh/m2/day) (kWh) ($) 1 2.81 411 49.35 2 3.19 429 51.48 3 4.34 647 77.61 4 5.47 780 93.63 5 5.74 826 99.06 6 5.58 773 92.73 7 5.42 771 92.49 8 5.02 714 85.62 9 4.36 600 71.94 10 3.64 518 62.13 11 3.02 416 49.92 12 2.45 353 42.3 Year 4.25 7236 868.26 BA B est Practices and NZEH Incremental Costs The incremental cost exercise identified the incremental cost, amortized annual cost, and increase in cost to construct per square foot; comparing the Gainesville Baseline to the BA Best Practices and the NZEH. The cost exercise generated the respective differences in cost for the builder/developer. These raw builder/developer costs were then converted to the homebuyer costs via a 10 % markup. Additionally, the c ost exercise provided the respective cost increases with and without accounting for rebates and incentives.

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77 BA B est Practices When comparing the Gainesville Baseline to the BA Best Practices the raw cost to the builder/developer was as follows: a total i ncremental cost of $620, an amortized annual cost increase of $49.56, and an increase in cost per square foot to construct of $0.41. The final cost per square foot to construct for the builder was $133.14. The first cost to the homebuyer was as follows: an increase in incremental costs of $682.00, an increase in amortized annual cost of $54.52, and an increase in cost per square foot to construct of $0.45. The final cost per square foot to construct to the homebuyer was $146.46. When factoring in the a pplicable rebates and incentives the costs were as follows: a decrease in incremental costs of $8,492.52, a decrease in amortized annual cost of $677.96, and a decrease in cost per square foot to construct of $5.66. The first cost to the homebuyer for the Gainesville Baseline home is $219,000 while the first cost for the BA Be st Practices is $219,686.50. The final cost to the homebuyer, including all rebates and incentives, for the Gainesville Baseline home is $211,000 while the final cost for the BA Be st Practices is $211,193.98. The final cost per square foot to construct the Gainesville Baseline home was $140.67 while the final cost per square foot to construct the BA B est Practices home was $140.80. The detailed results of the cost exercise can be vi ewed in Appendix D. NZEH When comparing the Gainesville Baseline to the NZEH the raw cost to the builder/developer was as follows: a total incremental cost of $73 ,357.60, an amortized annual cost increase of $ 5862.84 and an increase in cost per sq uare foo t to construct of $48.91. The final cost per square foot to construct for the builder was $181.64. It is important to note that these figures represent a 70 % reduction in energy consumption and do account for the photovoltaic array. Local developer Richard Schackow explained that when the

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78 builder/developer is responsible for installing the PV array, both the builder/developer and the homeowner are unable to receive the rebates and incentives ( Schackow, personal communication June 15, 2009). Subsequentl y, the first cost to the homebuyer including the PV array was as follows: an increase in incremental costs of $ 80,693.36, an increase in amortized annual cost of $6,449.12, and an increase in cost per square foot to construct of $53.80. The final cost per square foot to construct the NZEH with PV array to the homebuyer was $199.80. When assuming the home qualified for the rebates and incentives the costs were as follows: an increase in incremental costs of $ 31,556.44, an increase in am ortized annual cost of $2,526.20, and an increase in cost per square foot to construct of $21.04. The first cost to the homebuyer for the NZEH with PV array was $ 299,697.86. The final cost to the homebuyer, including all rebates and incentives, for the NZEH with PV array i s $ 250,560.94. The final cost per square foot to construct the NZEH with PV array was $167.04. The detailed results of the cost exercise can be viewed in Appendix E. Gainesville Baseline, BA Be st Practices NZEH Comparison Comparisons between the three h omes incremental costs were generated. The comparisons fall into two categories; builder/developer costs and homebuyer costs. Builder/Developer Costs There are two metrics which the builder/developer costs have been compared upon; incremental cost and c ost per square foot to construct. Figure 4 3 shows the incremental cost to the builder/developer for each of the modeled homes. It is important to note that these incremental costs for the NZEH include the PV array unadjusted cost. If the builder/developer installs the PV array then the full cost is transferred to the homebuyer as the builder/developer is unable to capitalize on the rebates and incentives. The Gainesville Baseline has no value as it is the value being compared against.

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79 Figure 4 3. Builder/developer incremental costs The cost per square foot to construct for each of the homes can be viewed in Figure 44. Again, it is important to note that in the case of the NZEH this value includes the PV array raw costs 132.73 133.14 181.64 0 20 40 60 80 100 120 140 160 180 200 Cost/SF Gainesville Baseline BA Best Practices NZEH Figure 4 4. Builder/developer cost per sf to c onstruct

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80 Homebuyer Costs The costs to the homebuyer have been compared on the metrics of incremental first cost (Figure 4 5), first and final cost to construct per square foot (Figure 46), rebates and i ncentives (Figure 4 7), and first and final complete costs (Figure 48). Figure 4 5 illustrates the incremental first cost to the homebuyer. This figure was determined by adding a 10 % markup on the builder/developer costs. The figure represents a scen ario in which the homebuyer is purchasing a turnkey NZEH. That is to say that the builder/developer has installed all energy efficient features, including the PV array, prior to being purchased by the homeowner. In this situation the high first cost of the PV array and Solar Thermal DHW system are apparent. Figure 4 5. Homebuyer incremental first c ost Figure 4 6 shows the first and final cost per square foot to construct to the homebuyer. The first costs to the homebuyer assumes the purchase of a turn key NZEH, whereas the final cost per square foot assumes the homebuyer was able to capitalize on the rebates and incentives

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81 available to them. The only entity who may capitalize on the incentives and rebates is the owner. Thus, in order for the homebuyer to make use of the rebates and incentives available they would have to install the applicable energy efficient features under separate contract. Doing so significantly impacts the cost per square foot to construct, as seen below. Figure 4 6. Homebuyer first/final cost/sf to c onstruct Figure 4 7 tallies all applicable federal/state rebates and incentives available for each of the home schemes. This study has assumed the home to be the homebuyers first home purchase, resulting in the Gainesville Baseli nes $8,000 of rebates and incentives. This federal tax credit was applied to all cases. Furthermore, the energy efficient homes includes the savings from the added energy efficiency. The excess energy saved, as compared to the Gainesville Baseline, was given a discount value by multiplying the number of kWh annually saved by the prevaling cost per kWh in Gainesville. In the NZEH case, the excess energy generated by the PV array was sold back to the grid under the Gainesville Regional Utilties Feed In T ariff rate. The detailed data for calculating these costs can be viewed in Appendices D and E.

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82 Figure 4 7. Homebuyer rebates and i ncentives Figure 4 8 shows the first and final complete cost to the homebuyer. These values were determined by multiplyin g the respective costs per square foot to construct by the desired size of 1500 square foot. Figure 4 8. Homebuyer first and final complete c osts

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83 CHAPTER 5 SUMMARY, CONCLUSIONS LIMITATIONS, AND RECOMMENDATIONS Summary This thesis has presented a n overview of the past and present trends in energy efficient home design. The work focused on the U.S. Department of Energy Building Technologies (BT) and Building America (BA) programs. As stated, the BT programs overarching goal is to obtain net zero ene rgy commercial buildings by 2025 and net zero energy homes (NZEH) by 2020. While the author acknowledged the challenge put forth by the BA program, this thesis aimed to determine the feasibility of designing and building multiple NZEHs to create a netzer o energy community (NZEC) in hot and humid climates. The specific location for which feasibility was concluded is Gainesville, Florida. Gainesville was chosen for its demonstrated acceptance of energy efficient homes and large number of BA partner builde rs/developers and subsequent projects. T his feasibility analysis focused on the problem statement from the perspective of the builder/developer; ultimately can they gain an advantage in the marketplace by developing these NZEHs and NZECs and still be able to sell them at a competitive, profitable rate. To determine the prevailing cost per square foot to construct a new single family home in a community of Gainesville a market analysis was conducted. The results of the market analysis identified the tar get cost of $146 per square foot to construct the new single family homes. Furthermore, the market analysis studied prevailing BA partner builders/developers in the area and found that their price per square foot to construct was identical to the non BA homes. These builders/developers have demonstrated the ability to provide, at minimum, a home which is 30 % more efficient at no incremental cost to the homebuyer. Consequently, this thesis identified the greater marketability and subsequent higher sales of the BA homes, as compared to a typical Gainesville home.

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84 The next phase of this work developed energy models, using the National Renewable Energy Laboratory (NREL) Energy 10 software, which represent the typical Gainesville h ome, a home built to the BA 2004 B est Practices standards, and a NZEH in the area. The reason for de veloping and testing the BA 2004 Be st Practices home was to validate that the program works. The BA 2004 Be st Practices identifies the means and methods to reduce energy consumpti on from the baseline by 30 % The result of the Energy 10 simulations was an averaged reduction of about 30 % proving that the program works from an energy perspective. Subsequently, the NZEH was developed to future BA standards; which would result in a 70 % reduction in energy consumption and 30 % production of energy onsite. However, the caveat of the BA program is that the energy goals must be met at little to no incremental cost to the homebuyer. Accordingly, the thesis then identified the incremental costs for each of the modeled energy efficient homes. The added energy efficient features were broken down line by line and evaluated based on incremental cost, annual amortized cost, and increase in cost per square foot to construct. These costs wer e tallied and separated into the cost to the builders/developers and cost to the homeowner; the difference being a 10 % markup by the builder/developer to the homeowner. Conclusions As mentioned above, the BA 2004 Be st Practices home was evaluated to det ermine the effectiveness of the BA publications. The BA 2004 Best Practices manual provides the means and methods to reduce energy consumption in a residence by 30 % with little to no incremental cost. Incremental cost for the BA Best Practices home was determined to be $0.46 per square foot to construct without rebates and incentives. After accounting for these savings, the BA Best Practices home had an incremental cost per square foot to construct of $0.13. The calculated costs and modeled energy savi ngs confirm the validity of the BA program and Best Practices

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85 publications. Moreover, this conclusion helps validate the future studies and publications of the program by demonstrating their effectiveness. Feasibility of NZEHs and the NZEC concept will now be discussed. This thesis approached testing the feasibility of NZEHs and NZECs from the perspective of the builder/developer. By approaching the problem in this manner feasibility is influenced by more than the final cost per square foot to construct While this metric is the primary determining factor, a builder/developer will consider outside metrics when deciding whether or not to pursue these advanced home concepts. Therefore, feasibility has been discussed in two sections. First, this work has evaluated feasibility based on cost per square foot to construct the single family home. Cost before rebates and incentives has been evaluated as well as cost analysis which factors in rebates and incentives; limitations relating to these savings will be discussed. Second, this work attempted to examine feasibility from a more holistic perspective. This analysis discussed the difficult to quantify benefits of building NZEHs and NZECs. Due to the lack of information, t he latter feasibility examination w as included in the limitations section to follow. Financial Feasibility Analysis First Cost Analysis This work has documented the incremental costs of building a single family home in a hot and humid climate to meet the BA standards of a NZEH. BA defines a NZEH as a reduction in baseline energy consumption of 70 % and onsite production of the excess energy used. The incremental cost to the builder/developer to construct a home that results in a 70 % reduction in energy is $11.57 per square foot. Factori ng in the onsite photovoltaic (PV) system, the price is increased by another $37.33. The final cost to the builder/developer to construct a NZEH is $181.64 per square foot. Accounting for the typical builder/developer markup of 10 % the price

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86 per square foot which the builder/developer is able to market the home at is $199.80. The market analysis for Gainesville identified an average cost per square foot to construct a new single family home of $146.00. Comparing the NZEH cost to the Gainesville average and BA Be st Practices the NZEH and NZEC concept is not financially feasible at this time. The NZEH is roughly 36 % more expensive than the Gainesville Baseline and the BA B est Practices The author acknowledged the fact that a premium product is often accompanied by a premium price, the price differential is simply too significant for community scaled implementation of such a home. However, the cost is not so high that a builder/developer may be able to implement a few specifically targeted NZECs and be met with great success. Finding the ideal location for these communities would require additional research. Final Cost Analysis Currently, significant reductions in the cost of many of the energy efficient systems implemented can be had through federal /state rebates and other utility provider incentives. When factoring in all applicable rebates and incentives the cost per square foot to construct the NZEH reduces to $167.04. This cost is $26.37, or roughly 15 % greater than the reduced Gainesville Bas eline home cost per square foot to construct. Considering that many homes, including BA partner G.W. Robinson, in communities of Gainesville sell for $165 per square foot the reduced final price for the NZEH is feasible. A major caveat of the rebates and incentives is that the builder/developer is not entitled to any of the savings. Subsequently, there is no financial incentive for a builder/developer to build a turnkey NZEH. The homeowner is the entity who can capitalize on the rebates and incentives. A shift in the politics relating to the rebates and incentives is necessary for builders/developers to buy into the NZEH and NZEC concept.

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87 Net Zero Energy Ready Communities A slight twist on the concept of the NZEC could ensure its feasibility today. Builder s /developers could construct homes within the communities to achieve the BA identified 70 % energy reduction and require the homebuyer to install a PV array resulting in a minimum of 30 % additional onsite energy within a certain timeframe. These h omes would be marketed as net zero energy ready (NZER) and placed within net zero energy ready communities. There are several advantages to this proposal. First, builders/developers are able to build a home to a HERS Index of 30 (70 % reduction) at a cos t to construct per square foot of $144.30 and sell it to a homebuyer at $158.73 per square foot. While the price increase over the baseline is not negligible, it is reasonable and below the mentioned common price of $165 per square foot in the area. Secon d, the builder/developer could tailor the lots and layout of the community to amplify the energy savings of the employed systems. This thesis averaged the energy models results and PV analysis from the four cardinal directions. While the energy models di d not vary greatly, the output of the PV system fluctuated significantly correlating to exposure direction. Panels which were modeled exposed to the South averaged roughly 60 % higher output than panels exposed to the West. Currently, lot premiums are a ttached to over sized and waterfront lots. In a NZER community the builder/developer would be able to offer premium lots based on orientation. The lots with a Southern exposed roof would require a smaller PV array to supplement the home s energy use, and thus lower overall cost to the homebuyer installing the PV array. Finally, the builder/developer could install a supplemental PV array within the community to aide in community wide energy consumption. Ideally, this would be placed on the builder/developer owned clubhouse; doing so would allow the builder/developer to take advantage of the applicable rebates and incentives as they are the owner. If they builder/developer would

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88 demonstrate this level of commitment to the success of the NZEC concept, they would likely benefit from a greatly improved image and pride in ownership as well. Limitations This thesis was limited by a few factors. First, the metrics by which holistic feasibility could be concluded upon are difficult to identify and quantify. Second, this work was unable to attain quantifiable reductions in the associated cost/time reductions for developing repetitive NZEHs to create NZECs. Third, this thesis has examined feasibility based in first cost only. The work has not considered operation and maintenance cost, or examined feasibility from a life cycle cost perspective. Finally, Energy 10 was discovered to have some limitations which would have impacted the PV array sizing and ultimately feasibility itself. Holistic Feasibility Analysis A holistic approach toward analyzing feasibility of NZEHs and NZECs in hot and humid climates could aide in validating the increase in cost per square foot to construct. To reiterate, the main goal of the builder/developer is to make money. Therefore, so long as the units are selling, regardless of price, the project is feasible to the builder/developer. For the purpose of this thesis, the holistic feasibility analysis has been conducted examining benefits to the builder/developer related to cost, company image, and culture of the project site. Company image can have a significant impact on the public acceptance of said companys product. Consequently, by making the conscious decision to build highly energy efficient communities, such a s NZEC s the bui lder/developer will benefit from improved public acceptance and perceived image. This cost is difficult to quantify but has an obvious impact on marketability. Whether or not this improved image will be beneficial is largely dependent upon the local cult ure. There are nodes throughout the United States which are more receptive to environmentally friendly energy efficient buildings. In these areas consumers are more willing

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89 to pay the premium associated with NZEHs and NZECs. The location of this feasibi lity analysis represents a prime example of such a culture. As identified by Gainesville developer Richard Schackow, Gainesville is quite accepting of energy efficient homes and communities. The level of acceptance is difficult to quantify and requires f urther research. However, this work concluded that given the culture and demonstrated historical buy in of energy efficient trends in Gainesville that NZEHs, NZECs, and NZER Communities are all currently feasible. Quantifying Material and Time Reductions when Developing NZECs As described, the repetitive nature of building and developing communities often yields the builder/developer reductions in the prices of materials and labor. In the beginning there is a learning curve for workers and suppliers, howe ver this learning curve reduces with each successfully completed residence. Additionally, the homes are very similar, requiring many of the same materials in known quantities. This fact allows builders/developers to order bulk quantities of materials whe n erecting multiple homes in different phases of construction. It proved very difficult to find quantifications of said reductions in time and capital. If this work would have been able to include these savings, the feasibility of the concepts presented could have been significantly impacted by including these discounts. Energy 10 Limitations Energy 10 proved to be an easy to use and effective means to model the associated energy models. However, during the exercise some short comings of the software wer e discovered. The most significant hindrance of the software was the inability to model a Solar Thermal Desiccant Cooling System (SDCS). The literature review identified a SDCS as a means to significantly reduce the cooling load of the residence. Howeve r, the only options for modeling HVAC equipment were conventional varieties. Another limitation of Energy 10 identified was the material library for assemblies. This shortcoming became apparent when attempting to model

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90 the ICYNENE wall system in the NZEH While it is possible to create your own materials and assemblies, it requires a fair amount of technical data and expertise not commonly available to the average user. If the next version of the software were to include these abilities the softwares validity would be significantly improved. Recommendations for F uture Research Several recommendations for future research have been identified. First, one of the most valuable metrics which requires quantificatio n is how much of a premium homebuyers are willing to pay to own a NZEH. This information becomes even more valuable when the target population of said research is within the area the NZEH or NZEC will be implemented in. Second, research identifying the goals and expectations of builder/developer s will prove to be invaluable. Third, quantification of additional design fees, and subsequent additional time allotted is needed to accurately represent the incremental cost of NZEHs and NZECs. Fourth, research into the development of prefabricated, modular NZEHs as a means to reduce construction duration/cost and increase tightness/quality would prove valuable. Fifth, life cycle costing and a nalysis exercises should be conducted to test the true viability of Solid State Lighting. Additionally, the information generated from this research should be used to test feasibility of the concepts from a life cycle cost perspective. Finally, configuration of the NZEH envelope should be heavily studied to identify the lowest incremental cost systems which yield the greatest performance increase. Specifically insulated slabs, which the DOE BT program has identified as an area in which energy efficient developments are needed.

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91 APPENDIX A GAINESVILLE BASELINE VS BA B EST PRACTICES ENERGY10 DATA Energy 10 Input/O utput 0 Degrees

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92 90 Degrees

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93 180 Degrees

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94 270 Degrees

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95 Example Comparative Bar Chart

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96 APPE NDIX B GAINESVILLE BASELINE VS NZEH ENERGY10 DATA Energy 10 Input/Output 0 Degrees

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97 90 Degrees

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98 180 Degrees

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99 270 Degrees

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100 Example Comparative Bar Chat

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101 APPENDIX C PV WATTS DATA Solar Radiation AC Energy Energy Value Solar Radiation AC Energy Energy Value Month (kWh/m2/day) (kWh) ($) Month (kWh/m2/day) (kWh) ($) 1 4.27 661 79.32 1 2.86 429 51.48 2 4.3 599 71.88 2 3.32 453 54.36 3 5.41 822 98.64 3 4.43 663 79.56 4 6.1 878 105.36 4 5.49 778 93.36 5 5.84 839 100.68 5 5.75 824 98.88 6 5.52 762 91.44 6 5.57 767 92.04 7 5.45 776 93.12 7 5.27 743 89.16 8 5.38 768 92.16 8 4.97 704 84.48 9 5.14 718 86.16 9 4.36 603 72.36 10 4.81 706 84.72 10 3.63 521 62.52 11 4.5 652 78.24 11 3.08 427 51.24 12 3.76 577 69.24 12 2.41 348 41.76 Year 5.04 8759 1051.08 Year 4.27 7259 871.08 Solar Radiation AC Energy Energy Value Solar Radiation AC Energy Energy Value Month (kWh/m2/day) (kWh) ($) Month (kWh/m2/day) (kWh) ($) 1 1.26 133 15.96 1 2.83 422 50.64 2 1.97 231 27.72 2 3.17 433 51.96 3 3.14 442 53.04 3 4.38 660 79.2 4 4.7 665 79.8 4 5.59 800 96 5 5.52 803 96.36 5 5.85 836 100.32 6 5.57 780 93.6 6 5.67 782 93.84 7 5.31 762 91.44 7 5.64 802 96.24 8 4.58 652 78.24 8 5.16 730 87.6 9 3.47 464 55.68 9 4.45 613 73.56 10 2.36 303 36.36 10 3.74 541 64.92 11 1.46 153 18.36 11 3.05 432 51.84 12 1.1 110 13.2 12 2.54 375 45 Year 3.38 5498 659.76 Year 4.35 7425 891 Average Month (kWh/m2/day) (kWh) ($) 1 2.81 411 49.35 2 3.19 429 51.48 3 4.34 647 77.61 4 5.47 780 93.63 5 5.74 826 99.06 6 5.58 773 92.73 7 5.42 771 92.49 8 5.02 714 85.62 9 4.36 600 71.94 10 3.64 518 62.13 11 3.02 416 49.92 12 2.45 353 42.3 Year 4.25 7236 868.26 7 kW Array Southern Orientation 7 kW Array Western Orientation 7 kW Array Northern Orientation 7 kW Array Eastern Orientation

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102 APPENDIX D BA BEST PRACTICES INCREMENTAL COST Building Gainesville BA 2008 Incremental Amortized* Increase in System Baseline Benchmark Cost Annual Cost $/sf Thermal Envelope Windows Double-Pane Aluminum Double-Pane Vinyl Low E Wall Insulation Fiberglass Batt, R-11 Fiberglass Batt, R-13 Ceiling Insulation R-30 Fiberglass R-30 Fiberglass Envelope and Duct Sealing/ACH None/0.3 Mastic and Caulk/0.2 $350.00 $27.96 $0.23 Wall Framing System Standard 2x4 Standard 2x4 HVAC System Heating System 80% Gas 93% Gas $400.00 $31.92 $0.27 Capacity 100Kbtu 60Kbtu Cooling System SEER 13/EER 11.2 SEER 14/EER 11.8 $350.00 $27.96 $0.23 Capacity 5 tons 3.5 tons -$1,500.00 -$119.76 -$1.00 Setup/Setback None None Duct Leakage 6% to out 4% to out Economizer Cycle None None Domestic Hot Water Water Heater Efficiency (Gas) 60% 83% tankless $900.00 $71.88 $0.60 Lighting General Lighting Incandescent Full CFL $120.00 $9.60 $0.08 Builder Price to Construct per SF $132.73 $133.14 $620.00 $49.56 $0.41 Homebuyer First Cost per Sf With Builder 10% Markup $146.00 $146.46 $682.00 $54.52 $0.45 First Cost to Homebuyer $219,000.00 $219,686.50 Rebates and Incentives Federal New Home Tax Credit Qualifies Qualifies $8,000.00 -$638.64 -$5.33 GRU Tankless Gas DHW Rebate Qualifies $350.00 -27.96 -$0.23 Energy Savings Annual Energy Consumption/Savings 22475 kWh Used 6871 kWh Saved $824.52 -$65.88 -$0.55 Total Rebates and Incentives $8,000.00 $9,174.52 -$732.48 -$6.12 Final Incremental Cost of BA 2008 Benchmark to Homebuyer, with Rebates and Incentives -$8,492.52 -$677.96 -$5.66 Final Cost to Homebuyer to Complete/Adjusted Cost per Square Foot $211,000.00 $140.67 per SF $211,193.98 $140.80 *Amortization assumptions: 30 year loan, 7% Interest Rate, 12 Payments per year

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103 APPENDIX E NZEH INCREMENTAL COS T Building Gainesville BA Net-Zero Incremental Amortized* Increase in System Baseline Energy Home Cost Annual Cost $/sf Thermal Envelope Windows Double-Pane Aluminum Double-Pane Vinyl Low E Wall Insulation Fiberglass Batt, R-11 Icynene 5.5" R-23 $2,096.00 $167.28 $1.40 Ceiling Insulation R-30 Fiberglass R-60 Fiberglass $1,440.00 $114.96 $0.96 Envelope and Duct Sealing/ACH None/0.3 Mastic and Caulk/0.1 $350.00 $27.96 $0.23 Wall Framing System Standard 2x4 2 x 6 @ 24" O.C. $951.60 $75.96 $0.63 HVAC System Heating System 80% Gas 95% Gas Incl. In Package Capacity 100Kbtu 12Kbtu Cooling System SEER 13/EER 11.2 SEER 19/EER 14.1 $4,000.00 $319.32 $2.67 Capacity 5 tons 2 tons Setup/Setback None Yes, 66 F and 81 F Duct Leakage 6% to out 2% to out Economizer Cycle None None Domestic Hot Water Water Heater Efficiency (Gas) 60% 80% Solar Thermal DHW $5,000.00 $399.24 $3.33 Lighting General Lighting Incandescent Full SSL (LED) $1,520.00 $127.68 $1.01 Automated Lighting Controls None Yes, Perimeter Rooms $1,000.00 $79.80 $0.67 Appliances Energy Star Appliances None Yes, All Applicable $1,000.00 $79.80 $0.67 Builder Price to Construct per SF $132.73 $144.30 $17,357.60 $1,392.00 $11.57 Photovoltaic System 7 kW DC, Installed, $8k per kW None Yes $56,000.00 $4,470.84 $37.33 Builder Price to Construct per SF w/PV $181.64 $73,357.60 $5,862.84 $48.91 Homebuyer First Cost per Sf With Builder 10% Markup and PV System $146.00 $199.80 First Cost to Homebuyer $219,000.00 $299,697.86 $80,693.36 $6,449.12 $53.80 Rebates and Incentives Federal New Home Tax Credit Qualifies Qualifies $8,000.00 -$638.64 -$5.33 State of Florida PV Rebate Qualifies $20,000.00 -$1,596.72 -$13.33 ARRA Federal rebate Qualifies $16,800.00 -$1,341.24 -$11.20 GRU High Efficiency HVAC Rebate Qualifies $300.00 -$24.00 -$0.20 Gru Solar Water Heating Rebate Qualifies $500.00 -$39.96 -$0.33 Federal Solar DHW Rebate Qualifies $1,500.00 -$119.76 -$1.00 Energy Savings Annual Energy Consumption/Savings 22475 kWh used 15713 kWh saved $1,885.56 -$150.48 -$1.26 Excess Average Energy Sold back at GRU FIT Rate 473 kWh $151.36 -$12.12 -$0.10 Total Rebates and Incentives $8,000.00 $49,136.92 -$3,922.92 -$32.76 Final IncrementalCost of NZEH to Homebuyer, with Rebates and Incentives $31,556.44 $2,526.20 $21.04 Final Cost to Homebuyer Complete/Adjusted Cost per Square Foot $211,000.00 $140.67 per SF $250,560.94 $167.04 *Amortization assumptions: 30 year loan, 7% Interest Rate, 12 Payments per year

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104 L IST OF REFERENCES Allproducts. (2009). Image Retrieved on May 30, 2009, from: http://www.allproducts.com/environment/booster/Product 2008991021242.jpg Armistead, T. (2009). Distributed Generation: Everybodys in Business. Engineering News Record, June 1, 2009. Baechler, M. Love, P. (2005). Building America Best Practices Series: Volume 1. DOE. Washington, D.C. Balcomb, J.D. (1984). Passive solar research and practice. Energy and Buildings 7: p. 281295. Balcomb, J.D. (1986). Conservation and solar guidelines. Passive Solar Journal 3: p. 221248. Barkaszi, S. Dunlop, J. (2001). Discussion of Strategies for Mounting Photovoltaic Arrays on Rooftops in Proceedings of Solar Forum 2001 Solar Energy: The Power to Choose. Washington, D.C. Bent, D. (2008, August 23). Sustainability as core business strategy New Strait Times pp. 60. Biaou, A. Bernier, M. (2008). Achieving total domestic hot water production with r enewable energy Building and Environment 43, p. 651660. Binsacca, R. (2009). Raising the Bar; Green communities are providing builders and developers with attractive economies of scale and marketing advantages. Retreived on June 14, 2009 from: http://www.ecohomemagazine.com/greenbuilding/green communities provide attractive economies of scalemarketing adva ntages.aspx BuildingGreen.com. (2007). Z6 House High Performance Building Case Study. Retrieved May 28, 2009 from: http://www.buildinggreen.com.lp.hscl.ufl.edu/hpb/overview Eb erly, D. A. (2008). LEED EB Case Study: Achieving Platinum and the Energy Star Label for Corporate Headquarters. Energy Engineering 105(3), 2337. Energy Information Administration (EIA). (2003). Arizona Case Study. Retrieved on May 21, 2009, from: http://www.repp.org/articles/static/1/binaries/Arizona%20Case%20Study.pdf Engebretson, C.D. (1964). The Use of Solar Energy for Space HeatingM.I.T. Solar House IV, i n: Proceedings of the UN Conference on New Sources of Energy, vol 5. Fainelli, M. (2001). Making the business case for going green. Christian Science Monitor, 93(27), 1719.

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105 Feyka, S. Vafai, K. (2007). An investigation of a falling film desiccant dehumidification/regeneration cooling system. Heat Transfer Engineering, 28(2): 163172. Fischer, J., Finnell, J. (2007). Energy and Buildings. Energy Series #9. Freese, W. (2007). The Business Case for Sustainability New Directions for Institutional R esearch, 134(Summer 2007), 2735. FSEC. (2009). Preliminary Performance Evaluation of a Near Zero Energy Home in Gainesville, Florida. Retrieved on May 10, 2009 from: http://ww w.fsec.ucf.edu/en/publications/pdf/FSEC CR179209.pdf GLSL, Green Life Smart Life. (2009). The Cost of PVIs There a Payback? Retrieved on June 3, 2009 from: http://greenlifesmartlife.wordpress.com/2009/02/11/the cost of pvis therea payback/ Goetzberger, A. (2005). Crystalline Silicon Solar Cells Retrieved on May 26, 2009 from: http://users.ictp.trieste.it/~smr1679/Goetzberger_2.pdf Green. (2009). LED Retrofits for Conventional Light Bulbs. Retrieved on June 14, 2009 from: http://www.gr eenandmore.com/LED conventional incandescent retrofit lamps.html Haggard, J. Young, W. (2006). Functional Disaster Resistant Buildings. Florida Solar Energy Center. Cocoa, FL. Halliday, S. Beggs, CB. Sleigh, PA. (2000). The Potential for Solar Desicc ant Cooling in the UK. Dublin. Hanes, T. (2007, July 7). First platinum house in U.S. certified last year The Toronto Star, pp. H14. Hendron. R. (2008). Building America Research Benchmark Definition. Retrieved on May 22, 2009 from: http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/44816.pdf Hilgers, L. (2008, October 6). Interface sets the pace for going green Plastics News Home Energy. (2009). Infiltartion: Just ACH50 Divided by 20. Retrieved June, 14 2009, from: http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/94/940111.html Ic ynene. (2008). ICYNENE LD R 50 and LEED for Homes. Retrieved on June 11, 2009, from: http://www.icynene.com/assets/documents/pdfs/ICYNENE LD R 50and LEED for Homes FINAL.pdf

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106 Johnson, J. (2006, October 23). DuPonts Focus; reducing emissions, conserving water part of companys mission. Waste News. Kalogirou, S. (2009). Thermal performance, economic and environmental life cycle analysis of thermo siphon solar water heaters. Solar Energy 83, p. 3948. Kibert, C. J. (2002). Policy instruments for a sustainable built environment. Retrieved May 15, 2009, from: http://www.law.fsu. edu/journals/landuse/vol17_2/kibert.pdf Mago, J. Chamra, L. Steele, G. (2006). A simulation model for the performance of a hybrid liquid desiccant system during cooling and dehumidification. International Journal of Energy Research, 30 51:66. McIlvai ne, J. Chandra, S. Fonorow, K. (2008). 40% Community Case Study G.W. Robinson Builders DOE BA Program. Midwest Renewable Energy Association (MWRA). (2009). Solar Domestic Hot Water; Midwest Renewable Energy Association Fact Sheet. Retrieved on May 24, 2009, from: http://www.the mrea.org/download/SolarHotWaterFactSheet.pdf North Carolina Solar Center (NCSC). (2002). Passive and Active Solar Domestic Hot Water Systems. Raleigh N.C. Palmiter, L. (1981). Optimum conservation for northwest homes, in: Proceedings of the 6th National Passive Solar Conference Portland, OR. Palmiter, L., Hanford, J. (1985). Measured performance of three superinsulated homes in Montana, in Cons ervation in Buildings: A Northwest Perspective. National Center for Appropriate Technology. Butte, MT. Parker, D. 2009. Very low energy homes in the United States: Perspectives on performance from measured data. Energy and Buildings 41: p. 512 520. P arker, D., Dunlop, J. (1994). Solar photovoltaic air conditioning of residential buildings, in: Proceedings of the 1994 Summer Study on Energy Efficiency in Buildings. Quinn, Barbara, (2007, November 12). The business case for sustainable thinking. Poll ution Engineering. REW. (2008). NREL sets thin film record. Retrieved on May 30, 2009 from: http://www.renewableenergyworld.com/rea/news/article/2008/03/nrel sets thin filmrecord 51958 Seidi, K. (2009). Longleaf: Gainesville Real Estate Report. Retreived on June 12, 2009 from: http://www.we promise.com/blog/?p=405

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107 SERI. (1984). Passive S olar Performance Summary of 19821983 Class B Results. SERI/SP2712362. Golden, CO. Solair. (2009). Desiccant Cooling Systems. Retrieved on May 22, 2009 from: http://www.solair project.eu/146.0.htm l Solarbuzz. (2009). Solar Cell Technologies. Retrieved on June 1, 2009 from: http://www.solarbuzz.com/Technologies.htm Toolbase Services. (2009). Desiccant Cooling. Retrieved on May 24, 2009 fr om: http://www.toolbase.org/Technology Inventory/HVAC/desiccant cooling U.S. Department of Energy. (2008). Building Technologies Program: Planned Program Activities for 2 0082012. Energy Efficiency and Renewable Energy. Washington, D.C. U.S. Department of Energy. (2009a). Whole House Approach Benefits Builders, Buyers and the Environment Building America Program. Washington, D.C. U.S. Department of Energy. (2009b). A bout Building America. Retrieved on May 19, 2009 from: http://www1.eere.energy.gov/buildings/building_america/about.html U.S. Department of Energy. (2009c). Building Ameri ca Puts Residential Research Results To Work Building America Program. Washington, D.C. U.S. Department of Energy. (2009d). Publications. Retrieved on May 17, 2009 from: http://www1.eere.energy.gov/buildings/building_america/publications.html U.S. Department of Energy. (2009e). Glossary of LED Terms. Retireved on May 18, 2009 from: http://www1.e ere.energy.gov/buildings/ssl/terms.html WBCSD. (2002). The Business Case for Sustainable Development: Making a difference toward the Johannesburg Summit 2002 and Beyond. Switzerland. Yudelson, J. (2008). The Business Case for Green; with multiple bene fits, green buildings make good business sense. HPAC Engineering, 80(3), 7 8.

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108 BIOGRAPHICAL SKETCH Robert Lamb graduated from Mariner High School (Cape Coral, Florida) in 2003 with honors. From there he attended the U niversity of Florida pursuing an und ergraduate degree in a rchitecture. Throughout those four rigorous years he learned a tremen dous amount regarding design. Robert received his b achelor s de gree in 2007, graduating Magna c um Laude. There is nothing in this world he would trade those f our years for; however, when the time c ame to pursue graduate studies Robert made the switch to the M.E. Rinker Sr. School of Building Construction at the University of Florida. He maintain s an immense appreciation for the process subjectivity, and resul ts of design, but he r ealized that he was not going to be the next great architect and left it at that. During his time in design Robert Lamb became intrigued by the emerging sustainable building movement. Throughout his graduate studies he has focused on the, Green, building movement and how it is reshaping our bui lt environment. Consequently, Robert obtained his United States Green Building Council Leadership in Energy & Environmental Design Accredited Professional credential (LEED AP) in 2009. R obert has obtained his Master of Science in Building Constr uction with a concentration in sustainable construction. He hope s to implement his passion for sustainable building and design in the construction industry throughout his career, all the while advoc ating upand coming sustainable cons truction means and methods. Robert aspires to one day return to the University of Florida for his doctorate degree and the opportunity to profess at the college level.