1 S IMULATING THE IMPLEMENTATION OF ENERGY EFFICIENCY MEASURES, TECHNIQUES AND TECHNOLOGIES ON RESIDENTIAL AND COMMERCIAL BUILDINGS By JILLIAN S. BECKER A MASTERâ€™S RESEARCH PROJECT (MRP) PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN ARCHITECURAL STUDIES WITH A CONCENTRATION IN SUSTAINABLE DESIGN UNIVERSITY OF FLORIDA 2015
2 2015 Jillian S. Becker
3 To my friends, family , and, most especially, to Jenny and Toby for being my constant companions throughout the many hours of work it took to complete this project.
4 ACKNOWLEDGMENTS I would like to extend many thank s to the faculty and staff of the MSD program for thei r contributions to my education throughout this year , and especially to Dr. Ries and Professor Walters for serving on my committee and helping in the process of completing my MRP. Your thoughts, ideas and comments have been invaluable contributions to the completion of this project.
5 TABLE OF CONTENTS p age ACKNOWLEDGMENTS..4 TABLE OF CONTENTS..5 LIST OF TABLES.8 LIST OF FIGURES ... 9 LIST OF DEFINITIONS ..11 LIST OF ABBREVIATIONS .. . 12 ABSTRACT .. 13 INTRODUCTION.. ..15 LITERATURE REVIEW . 19 Sustainability ...19 Evolution of the Built Human Environment in the United States .19 Current Status of Buildings in the United States 1 Building Energy Use...22 Impacts of Building Energy Usage...24 Reducing Building Energy Consumption.2 5 Benefits of Improving Building Efficiency ....27 General Methods o f Improving Building Efficiency ....28 Energy Modeling Software.30 Case Studies 33 Complexities Involved with Improving Building Efficiency and Alternate Points of View .35 Summary ..39 METHODOLOGY 1 Existing Residential Energy Modeling .42 New Construction/New Design Residential Building Energy Modeling ..46 Existing Commercial Building Energy Modeling 8 New Construction Commercial Building .50 SURVEY OF ENERGY EFFICIENCY MEASURES, TECHNIQUES AND T ECHNOLOGIES ..52 Introduction and Intent ..52 Existing Residential Buildings ..52
6 Building Shell 2 Roofing ..53 Exterior Walls and Foundation. ..55 Win dows . 6 Exterior Doors . ..62 Attic . 3 Heating, Ventilation and Air Conditioning . 5 Natural Gas Furnaces . 7 Boilers ....68 Central Air Conditioners . 8 Heat Pumps . 0 Ducts . 0 Energy Recovery Ventilator ...71 Appliances ....72 Water Heater ... .73 Refrigerator ...74 Dishwasher 5 Clothes Washer and Dryer .75 Small Appliances ..76 Lighting ..77 Compact Fluorescent Lightbulbs ...77 Light Emitting Diodes ...78 New Construction Residential Buildings ...78 Orien tation .9 Building Envelope/Shell ..80 Roofing ..81 Exterior Walls/Foundation.....82 Attic 4 Windows ..4 Doors ...85 Heating, Venti lation and Air Conditioning ..86 Geothermal Heat Pump.. .86 Appliances..86 Lighting . 87 Existing Commercial Buildings . 88 Building Shell ..88 Roofing 89 Exterior Walls . 89 Windows/Doors ..89 Heating, V entilation and Air Conditioning. . 90 Appliances ..91 Lighting 92 New Construction Commercial Buildings . . 93 Conclusio n . . 94 ENERGY MODELING FINDINGS AND DISCUSSION.. ..... 96
7 Existing Residential Building .96 New Construction/New Design Residential Building 06 Existing Commercial Building ..113 New Construction/New Design Commercial Building ..121 CONCLUSIONS AND FUTURE WORK ........ 127 Existing Residential Building .127 Future Improvements to Research..127 New Construction/New Design Residential Building .128 Future Improvements to Research ..29 Existing Commercial Building ...130 Future Improvements to Research..131 New Construction/New Design Commercial Building ...133 Future Improvements to Research..134 Overall Conclusions 35 APPENDICES.. 139 I: Existing Residential Inputs..139 Analy sis and Results150 II: New Construction Residential Inputs66 Analysis and Results .. . 173 III: Existing Commercial Inputs..180 Analysis and Results...98 IV: New Construction Commercial Inputs.216 Analysis and Results . ..231 L IST OF REFERENCES. 237 LIST OF FIGURE REFERENCES .247 BIOGRAPHICAL SKETCH. 249
8 LIST OF TABLES Table p age Table 5.1 Table of efficiency improvements and estimated costs .98 Table 5.2: Summary of Findings for the Four Efficiency Retrofit Packages 03 Table 5.3 Energy Efficiency Retrofit Characteristics by Measure.104 Table 5.4 New residential consumption findings summary table..111 Table 5.5 New residential cost findings summary table.112 Table 5.6 Existing commercial energy consumption..116 Table 5.7 Ranking of existing commercial improvements by savings .119 Table 5.8 Cumulative Electricity and Gas Savings .120 Table 5.9 Electric and gas consumption with window variations ..124 Table 5.10 New construction commercial energy end use by percentage..126
9 LIST OF FIGURES Figure p age Figure 2.1 U.S . Energy Consumption by Sector..22 Figure 2.2 U.S. Electricity Consumption by Sector.22 Figure 2. 3 U.S. CO2 Emissions by Sector3 Figure 4.1 Selecting Energy Efficiency by Climate Zone8 Figure 4.2 Window Charact eristics for Different Climates . .59 Figure 4.3 Effective R values of vari ous types of window treatments. . .61 Figure 4.4 Recommended insulation levels for retrofitting woodframed buildings .65 Figure 4.5 Share of homes primary space heating fuel and Census Regi on, 2009.66 Figure 4.6 Water heating fuel by census division, 2005..3 Figure 4.7 Optimal orientation of a building to utilize passive solar benefits81 Figure 5.1 Analysis of annual energy consumption of exist ing residential building ....96 Figure 5.2 Annual Savings for Retrofits under the â€œTotalâ€ Package . 100 Figure 5.3 Annual Savings for Retrofits under the â€œBaseâ€ Package . 00 Figure 5.4 Annual Savings for Retrofits under the â€œShellâ€ Package . .101 Figure 5.5 Annual Savings for Retrofits under the â€œApplianceâ€ Package . 02 Figure 5.6 Enduse categories for new residential e nergy consumption and costs .. .106
10 Figure 5.7 Base model and window orientatio n results, new residential.108 Figure 5.8 Existing commercial energy enduse.....115 Figure 5.9 New construction c om mercial energy enduse....123
11 LIST OF DEFINITIONS Sustainability The principle of living in accordance with natureâ€™s boundaries, so as to not deplete the planetâ€™s resources and to allow future generations to have access to these same resources. Green Building Built structures that are more environmentally friendly than standard buildings, consume less energy and resources and are also associated with improved health and productivity. Energy Modeling The simulation of a buildingâ€™ s energy demands and consumption based on that buildingâ€™s characteristics. Energy Efficiency Products or design strategies that require less energy to operate Measures than standard counterparts, which reduce building energy needs.
12 LIST OF ABBREVIATIONS HVAC â€”Heating, ventilation and air conditioning SHGCâ€”Solar heat gain coefficient CO2 â€”Carbon dioxide CFL â€”Compact fluorescent lightbulb LED â€”Light emitting diode AFUE â€”Annual fuel utilization efficiency SEER â€”Seasonal energy efficiency ratio HSPF â€”Heating seasonal performance factor BTU â€”British thermal unit kWh â€”Kilowatt hour
13 Abstract of the Masterâ€™s Research Project Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements f or the Degree of Master of Science in Architectural Studies with a Concentration in Sustainable Design S IMULATING THE IMPLEMENTATION OF ENERGY EFFICIENCY MEASURES, TECHNIQUES, AND TECHNOLOGIES ON RESIDENTIAL AND COMMERCIAL BUILDINGS By Jillian S. Becker June 2015 Chair: Robert Ries Cochair: Bradley Walters Major: Master of Science in Architectural Studies with a Concentration in Sustainable Design The energy consumptive United S tates building sector serves as a unique opportunity for improvement in the effort to reduce energy consumption and associated environmental impacts, including global climate change. Existing and newly designed buildings in the residential and commercial sectors can be retrofitted or designed with efficiency in mind to contri bute to these muchneeded reductions in usage. Many energy efficiency measures, techniques and technologies exist that can be implemented into existing and newly designed residential and commercial buildings to enhance their efficiency and reduce operating costs. By examining an array of basic energy efficiency measures, an understanding of building efficiency can be developed, and by modeling the implementation of these measures into theoretical buildings, a case can be made for their relative effec tiven ess and appropriateness of being utilized in certain situations.
14 Research was conducted t o provide background information on the variety of efficiency measures, techniques and technologies applicable to existing and new design residential and commercial buildings. Many of these measures were then modeled as being implemented into existing and newly designed residential buildings in REM/ Rate , and commercial buildings in eQUEST. Overall, it was found that certain individual energy efficiency measures, as wel l as specific combinations of m easures , performed better than others in the four building types, and the implementation of efficiency measures was found to be beneficial in almost every case. While it should be noted that the exact results of the energy modeling performed in this study cannot be applied generally as only one geographic location was examined , the utilizatio n of energy efficiency technologies in buildings can provide energy saving and cost benefits on a much broader scale as well .
15 CHAPTER 1 INTRODUCTION We live in a continuously and rapidly changing world. The view from your bedroom window looks different today than it will months and years from now. It is drastically different from the way it was 50, 100, 1,000 and more years ago; for views to evolve and be altered is natureâ€™s way. Without natural changes and evolutions, we would have no mountain ranges, Grand Canyon, or complex forms of life. However, in recent years the view from your bedroom window may very likely look different because of changes made by humans. Fields and woods are paved over and replaced with shopping centers, new housing, roads filled with cars, and all means of development suited to human needs and desires. This type of development has increased in the last several human generations, transforming the way our world looks. Just consider the differences between the natural cave dwellings of so many ancient civilizations and familiar modern residential dwellings . The two serve the same basic purpose, but modern homes have a much greater impact on their surroundings , from construction throughout the operation of the building and its eventual demolition, since they are built and powered by manmade technologies . In contrast, cave dwellings were created by nature and did not require large amounts of energy to operate. This comparison exemplifies the idea that w ith increased advances in development has traditionally come greater impacts on our surroundings, and along with that, a host of environmental issues; pollution, loss of habit at and resources, and global climate change. Climate change is arguably the most pressing of these issues, caused by an increase in the concentration of carbon dioxide in the earthâ€™s atmosphere ( US EPA, 2014) . It is very
16 widely accepted in the global sci entific community that pollution from human activities is the cause of the heightened levels of carbon dioxide we see today. This leads one to wonder: if humans are the cause of the environmental problems we face, should we not also be the solution? As a population, humans need to make it a priority to act on our capability to make smarter decisions that do not inflict harmful changes on our surroundings. We need to do what we can to work with the earthâ€™s natural systems and ensure that our lifestyles fit within these systems, creating more of a symbiotic relationship than what has existed for the last several decades. A multitude of arenas exist in which we can focus our efforts and begin making these smarter decisions â€”transportation, alternative energy generation, and water conservation are just a few examples. Another area of importance that holds a lot of promise for reducing impacts on the environment is the building sector, on which this research topic is based. Americans spend an average of 90% o f their time inside buildings (US EPA, 2008), and consequently, buildings require a lot of energy to operateâ€”40% of all energy consumed in the United States, for instance (US EIA, 2013). This statistic may seem surprisingly high to some, however it provides an obvious opportunity for improvement, offering the potential for huge reductions in energy consumption in the U.S. building sector, and thus in the country as a whole. Knowledge of this vast potential for improvement in the building sector brings us to a series of relevant questions. What specific methods, technologies, and general improvements can be imposed on buildings to help achieve reductions in building energy consumption? How do these methods, technologies, and improvements vary
17 between the residential and commercial building sectors? How much energy could these individual energy saving measures actually save when implemented in residential and commercial buildings? These questions are the basis of what will be discussed and discovered in this research study. The variety of different measures and techniques that can be implemented in existing as well as new ly designed residential and commercial buildings will be explored and discussed in the first part of the research. This will be undertak en to give the reader an idea of the many possible ways that a building can be altered to reduce energy consumption and operating costs, some of which could be easily implementable in their own home or commercial building. After this â€œinventoryâ€ of energy ef ficiency measures is taken, many of them will be simulated in various combinations (in both new and existing residential and commercial buildings) using building energy modeling software in an attempt to determine quantitative values for the amount of e nergy and money saved in theoretical buildings in the Washington, D.C. area . The main argument of this paper is that all types of buildings will realize a reduction in energy consumption and operating costs when efficiency measures are modeled , whether they are implemented individually or in various combinations . The intention of this research is to attempt to contribute to an existing body of research and experimentation on building efficiency. This will be accomplished by providing quantitative numbers that will help strengthen the argument made by building performance advocates that enhancing a buildingâ€™s efficiency will save money and energy. If enough studies similar in nature to this one are performed that reach the same conclusions, the hope is that building performance will be made more of a priori ty in the United States and efficiency programs can take root in more places throughout
18 the country, and in turn reducing the 40% energy expenditure in the building sector. The information provided in this study is also, however, relevant on a much smaller, individual scale as well as a nationwide scale. Those looking to reduce their individual contribution to carbon emissions, save money, or improve aspects related to comfort in their building would be nefit from knowing more about building efficiency and by investing in efficiency measures could improve upon all three of the aforementioned concerns. Impacts from reductions in building energy consumption can be felt at many levels. This reduction has t he capacity to transform the experiences of individual people and building users, as well as reducing overall pollution, global climate change potential, and the need for coal fired power plants , among other implications . In the chapters that follow, a review of the existing literature concerning building performance and modeling techniques and software will be discussed to provide more context and background to this research study. Following the literature review will be a description of the methods us ed in the process of modeling the energy efficiency measures, followed by the inventory or survey of building efficiency measures, techniques, and technologies mentioned before. The findings from the energy modeling simulations, as well as a discussion and analysis of these findings, can be found following the survey. Finally, concluding remarks and ideas for future research and experimentation can be found in Chapter 6.
19 CHAPTER 2 LITERATURE REVIEW Sustainability M any operational definitions exist of the increasingly heard and studied term â€œsustainability.â€ Randolph and Masters define it as â€œpatterns of economic, environmental and social progress that meet the needs of the present day without reducing the capacity to meet future needsâ€ (Randolph, 2008). Williams terms it as â€œcontinuing, evolving and adapting to renewablesâ€ (Williams, 2007). John Randolph cites the Brundtland Commission definition of sustainable development as â€œpaths of economic, social, environmental, and political progress that aim to meet the needs of today without compromising the ability of future generations to meet their needsâ€ (Randolph, 2012). The United States Environmental Protection Agency ( US EPA) bases their definition â€œon a simple principle: everything that we need f or our survival and well being depends, either directly or indirectly, on our natural environmentâ€ ( US EPA, n.d). These definitions all have similar foundations, but the latter quote from the EPA stands out somewhat distinctly, because it highlights huma n dependence on the natural environment. This dependence will ultimately always dictate human limitations as long as our species inhabits the Earth. However, our relationship with nature, including the way we live in, react and conform to it, has changed fundamentally over time. Evolution of the Built Human Environment in the United States The early human built environment was inherently sustainable. People only had access to local, naturally sourced materials that were adapted to and suitable for the
20 o ccupied climate, such as animal hides, adobe and native vegetation and woods, to build their dwellings. These dwellings served a useful purpose without requiring construction materials that had wideranging environmental or ecological impacts. Early buil dings were built and adapted to fit into the local climate as well. The ancient Anasazi people of the present day southwestern United States were able to achieve a level of thermal comfort by orienting their adobe dwellings to the south to gain thermal hea t from the sun in the winter (Tzikopoulos et al, 2005). Their stone cliff dwellings, pueblos, were also built into the cliffs to allow overhangs that kept hot summer sun out of the interior (Tzikopoulos et al, 2005). Thermal storage in floors and walls was often used to heat and cool buildings when needed (Syed, 2012), but there wasnâ€™t a focus on thermal comfort, and other than biomass and animal fat, fuel was largely not used to influence the interior condition of the dwelling. As societies developed and became more technologically advanced, however, these sustainable building attributes were used less frequently in the built environment. Imported and manufactured building materials started being used more than locally sourced materials, which contribute to carbon dioxide (CO2) emissions (Reddy and Jagadish, 2003). Heating and lighting fuels such as kerosene were introduced that reduced the necessity of passive heating and employing natural light. The discovery of electricity and the invention and pr oliferation of the air conditioner and wholehome heating, ventilation and air conditioning (HVAC) systems was arguably a major turning point in the operation of buildings. As these technological advances occurred, buildings began to be more closed off and separated from nature and its sustainability principles. Local construction materials were no longer needed, because there were other, more
21 advanced options. Occupants of buildings didnâ€™t need to rely on the sun for light or warmth, because they had el ectricity and heating fuel. But once mechanically powered means of conditioning buildings in the form of air conditioners supplanted natural ventilation, humansâ€™ relationship to buildings really changed. We no longer needed to rely on sustainable principles to achieve comfort indoors. The aforementioned changes that took place in the built environment, especially in the second half of the 20th century, encouraged an evolution in American culture and lifestyle that we are now dependent upon, and that lar gely consists of being indoors in buildings powered by unsustainable resources. Current Status of Buildings in the United States Typical buildings in the United States today are very much separated and independent from the surrounding natural environment . Electricity and central heating and cooling are the norm, with artificial lights, electronic appliances, refrigerators, dishwashers, ovens, clothes washers and dryers, water heaters and other home appliances present in the vast majority of residential buildings, and to a certain extent, in commercial buildings as well. Buildings now exist for almost any conceivable human need, from sleeping to working to exercising . The development of different types of buildings that can meet so many of our needs and the now expected comfort and livability of the built environment has had a sizeable impact on human life. The built environment is a major component of our lives; as a country, Americans spend 90% of their time indoors ( US EPA, 2008 ). Our non sustainable buildings require electricity and other fuel sources to operate and provide the comforts that we have grown accustomed
22 to, and this high percentage of building use means that substantial amounts of energy are consumed by the building sector. Building Energy Use The building sector is in fact the largest consumer of energy in the United States, accounting for nearly half of the energy usage in 2014 , according to data from the U.S. Energy Information Administration (EIA) and presented in Figure 2.1 below ( US EIA, 2015). Also, according to the EIA and illustrated by Figure 2 .2 below , nearly 75% of all electricity produced in the U.S. annually is used by buildings for day to day operations ( US EIA, 2015 ). In fact, 8090% of building energy use is consumed by building operations (Ramesh et al, 2010). Through this high usage of energy, the building sector was found to be responsible for over a third of all carbon dioxide emissions in the country in 2014, seen in Figure 2. 3 on the following page ( US EIA, 2015 ) . Figure 2.1 U.S Energy Consumption Figure 2.2 U.S. Electricity Consumption by by Sector. Data obtained from U.S. EIA. Sector. Data obtained from U.S. EIA. Buildi ngs 41% [VALUE] QBtu's Indust ry 32% [VALUE] QBtu's Trans portati on 27% [VALUE] QBtu's Buildi ngs 74% [VALUE] QBtu's Indust ry 25.8% [VALUE] Trans portati on <1% [VALUE]
23 Figure 2. 3 U.S. CO2 Emissions by Secto r Data obtained from the U.S. EIA While these statistics are important in and of themselves, it is also useful to know how the energy that is being consumed in buildings is produced. In 2013, 67% of electricity in the United States was generated from fossil fuels, and 39% of that was from coal (EIA, 2014). Natural gas produced 27% of all electricity in the U.S. that same year, while petroleum produced 1% (EIA, 2014). Around 50% of the primary energy for day to day operational demand in buildings comes from the heating, ventilation and air conditioning (HVAC) system, which accounts for 20% of overall energy consumption in the United States (Perez Lombard et al, 2008). Natural gas, electricity and petroleum products are used in heating buildings, which comprised around 25% of energy use i n buildings in 2006 (Randolph, 2008). However, over 80% of homes built since 1970 use either electricity or natural gas for heating, and petroleum products are less commony used (EIA, 2012). More specifically , 99% of homes consume electricity for general purposes, 61% consume Buildin gs 39% [VALUE] MMT CO2 Industr y 27% [VALUE] MMT CO2 Transp ortation 34% 1832 MMT CO2
24 natural gas, 43% use propane, 12% use wood, and 7% use fuel oil (EIA, 2012). Natural gas accounted for 75% of primary consumption of fossil fuels in the residential building sector in 2013, and petroleum products accounted for 15% (EIA, n.d). Overall, the residential sector used 21% of the total primary energy in 2012, accounting for 20% of carbon dioxide emissions (EIA, 2015). In the commercial sector in 2012, 1% of fossil fuel primary consumption was used by coal, 80% was used by natural gas, and 15% was used by petroleum products (EIA, n.d). All of these sources of energy (coal, natural gas, and petroleum) that account for 75% of energy used in the building sector (DOE, 2012) are nonrenewable fossil fuels that contribute to a h ost of environmental problems, and the majority of our energy production relies on their use. If the majority of our energy production relies on the burning of fossil fuels, that means that the majority of our buildings are powered by these resources. I mpacts of Building Energy Usage Many far reaching implications result from this high use of nonrenewable energy by the building sector. Air, water and land pollution from the extraction to the burning of fossil fuels have degraded the quality of the envi ronment, impacting wildlife, humans, and landscapes alike (Karl et al, 2009). Each form of pollution brings about different negative consequences and externalities that cannot necessarily be seen or measured. A lso important is the significant contributio n to global climate change via the carbon dioxide emissions emitted to ultimately power buildings (Architect 2030, 2013). The potential impacts of global climate change include drought, intensified storms, sea level rise, human and animal displacement, am ong others (Karl et al, 2009). These impacts will be felt around the world in varying degrees, and will likely necessitate an increase in
25 energy consumed by buildings for cooling (Karimpour et al, 2015). It c ould even take the form of increased heating and cooling demand, depending on geographic location; although a reduction in heating loads was predicted for certain climate zones (Wang, 201 4 . A growing movement to curb carbon dioxide and other greenhouse gas emissions in an attempt to offset some of the impacts of global climate change is having varying success worldwide. S everal arenas are available to focus on that would help combat climate change, but in the United States, the energy intensive building sector has a great deal of room for improvement. And within the building sector, the energy it takes to operate each building on a day to day basis is substantial, accounting for 8090% of its lifecycle energy consumption (Ramesh et al, 2010). It stands to reason t hat this is the phase of the buildingâ€™s lifecycle that should be focused on if a sizeable reduction in energy usage is to be achieved. Reducing Building Energy Consumption Because Americans have grown accustomed to a certain lifestyle in which buildings a nd comfort play a large role, it would be impractical to suggest returning to a fully sustainable lifestyle, designing and constructing buildings to operate without any energy consumption. Si nce we canâ€™t easily go back, two methods can be employed to reduce energy consumption in the building sector: Conservation Efficiency Conservation entails cutting back on energy consumption as a whole, which would require individuals to use less energy in their residences , and for businesses operating
26 commercial buildings to do the same. Seligman and Darley determine from their study that â€œresidents can play an important role in energy conservation that complements engineering solutionsâ€ (Seligman et al, 1978). But this is dependent upon willful parti cipation, and many people would not want to sacrifice their comfort even if it meant saving energy and money on their utility bills. Another method of reducing energy use in buildings is by improving efficiency. The overall efficiency of buildings can b e improved by enhancing the performance and efficiency of its components, like lighting, heating, ventilation and air conditioning (HVAC) and major appliances, ducts, and the shell or envelope of the building. Making these types of changes to the building â€™s efficiency would make it inherently use less energy, and improve its overall sustainability. A n important distinction exists between efficiency and sustainability. Efficiency is a step towards sustainability, but they are not the same thing. Even highly efficient buildings use some energy to operate, a nd if this energy is obtained from combustion sources that directly create pollution and carbon dioxide emissions, the building is by definition not sustainable. S ustainable buildings are more or less self sustaining, utilizing natural, resident energies (Williams, 2007). This would include utilizing sunlight for illumination an d in passive heating, wind for natural ventilation and cooling. Williams notes that â€œthere are varying degrees of green design, but sustainable design is an absolute---the building can function unplugged. If the building or community is highly energy eff icient but cannot function unplugged, it is not sustainableâ€ ( p. 258). A truly sustainable building wouldnâ€™t be as comfortabl e by modern American societyâ€™s
27 standards in many climates , but efficiency improvements do a good job of bridging the gap between where we are now, and a sustainable society. Benefits of Improving Building Efficiency A few core benefits can be realized when a building is improved to consume less energy. The first benefit relates back to the concept of conservation to reduce energy consumption; unlike conservation, improving energy efficiency doesnâ€™t require a major lifestyle change. A higher efficiency building will consume less energy than a standard or lower efficiency building, even if the user behavior is exactly the same in both scenarios. A case for improving operating efficiency is made by Ramesh et al (2010) , who found in their building life cycle energy analysis that â€œbuildingâ€™s life cyle energy demand can be reduced by reducing its operating energy significantly through use of passive and active technologiesâ€ ( p.1 ). Another obvious benefit that also happens to be the purpose of high efficiency buildings is that they consume less energy and thus have less of an impact on the environment. One research study found that building higher efficiency buildings could decrease carbon dioxide emissions by upwards of 60%, or around 1.35 billion tonnes of carbon (Tzikopoulos et al, 2005). In consuming less energy, efficient buildings also cost less money t o operate. Lastly, comfort i s usually improved in buildings of higher efficiency as compared to standard or low efficiency buildings bec ause the efficiency elements wor king in conjuction with one anot her allow the building to retain conditioned air for lo nger periods of time, and keep unconditioned air out. It can be more difficult, however, to keep a low efficiency building conditioned appropriately depending on the time of year.
28 General Methods of Improving Building Efficiency All components of a building can be improved to reduce energy consumption, although some specific measures are better suited for different types of buildings, like residential or commercial, and existing or new construction. There are, however, general components of building s that can be enhanced for all four types of these buildings (existing residential, existing commercial, new construction residential and new construction commercial). These components are: Building shell Heating, ventilation and air conditioning (HVAC) and distribution system Lighting Appliances Water heating New construction buildings can also benefit from being oriented to take advantage of passive solar, and can be optimally and intentionally designed to operate passively. Randolph reports Michael Cor bettâ€™s findings that incorporating passive and efficient design principles could â€œbe done with little or no added investment, because of cost savings from downsized furnaces and air conditionersâ€ (Randolph, 2012: p. 351). A buildingâ€™s shell, which include s the walls, windows, doors, roof and foundation, can be improved in a few ways. Air sealing cracks and openings in the shell can reduce energy transfer via infiltration, and insulating the walls, roof and foundation reduces energy transfer via conduction. Multiple types of insulation can be used for different applications, from traditional fiberglass batts to more newly developed materials such as aerogel insulation (Baetens et al, 2011). In addition to aerogel insulation, newer state-
29 of the art thermal building insulation like insulated panels, phasechange materials and nano insulation materials could potentially be used in the future (Jelle, 2011). Windows and doors can also be replaced with high efficiency products that reduce energy leakage and prev ent heat gain and loss. Green roofs can be implemented and have the potential to assist in heating and cooling a building, although this dep ends on the climate as well as the buildingâ€™s characteristics (La Roche and Berardi, 2014). Of all the energy used in buildings , 37% was consumed by heating and cooling appliances in 2006 (Randolph, 2008). Continuing advances in efficiency and performance of HVAC systems have led to different ranges of high efficiency appliances, and upgrading a buildingâ€™s HVAC syst em to high efficiency appliances can improve the overall performance of the building. In 2014 , lighting a ccounted for around 15% of energy used in buildings and 11% of all electricity in the United States ( US EIA, 2014 ). Traditional incandescent bulbs are inefficient, losing 90% of the energy they consume as waste heat (Randolph, 2008). Fluorescent, compact fluorescent, and light emitting diode (LED) bulbs use a fraction of the energy that incandescent bulbs use, and last at least 10 times as long (DOE, n.d). Home appliances like refrigerators and electronics use 16% of energy consumed by buildings (Randolph, 2008). The US EPA created the Energy Star program in the early 1990s, which has developed high efficiency appliances that consume a fracti on of the energy as regular efficiency refrigerators, washers, dryers, TVâ€™s, laptops and numerous other types of home appliances. (Energy Star, n.d).
30 Water heating comprises 11% of energy demand in U.S. buildings (Randolph, 2008). H igher efficiency alt ernatives exist for water heaters, such as p ower vented, heat pump and tankless/demand water heaters , that can be used to improve the overall efficiency of a building (Energy Star, n.d). This brief overview of efficiency measures gives an idea of the extent of potential solutions for improving a buildingâ€™s efficiency , and more information can be found in Chapter 4. These methods can be used alone or in different combinations to improve the efficiency and performance of buildings, and there are a multi tude of evaluating steps a building can go through to determine which upgrades are necessary. A preretrofit survey, energy audit and performance assessment are the first steps for evaluating existing buildings, followed by the determination of different retrofit options (Ma et al, 2012). For new construction buildings or buildings under design, energy performance assessments need to be based on calculated ratings (Wang et al, 2012). A series of different energy modeling programs exist that can determine quantitative estimated energy and monetary savings after retrofit implementation, effectively comparing standard efficiency buildings with those that have had efficiency upgrades applied to them. Energy Modeling Software Early building modeling software d ates back to the mid 1970s and has progressed and become more sophisticated over the years to eventually include energy modeling components (Eastman, 1992). Different approaches to building energy modeling have been developed over this time period, including bottom up modeling systems that use extrapolation of data from â€œhighly representativeâ€ building samples to
31 similar buildings, and topdown modeling systems which seeks to predict the energy demand based on a buildingâ€™s function and floor area (Aksoezen et al, 2015). Steady state and dynamic energy models have also been developed, which are concerned with the climatic variations in estimating a buildingâ€™s energy performance (De Lieto et al, 2015). Software programs exist that can model the annual energy demand or consumption of individual residential or commercial buildings , or that can address peak demand by integrating comprehensive spatial and temporal data in addition to building data (Dirks et al, 2015). Similarly , smart building energy manag ement systems are capable of monitoring real time weather conditions and adjusting a buildingâ€™s energy operations based on this information, serving as a kind of real time energy modeling program (Rocha et al, 2015). This type of application could prove t o be most useful in commercial buildings where energy demand and consumption is greater and building controls require more involved management. Many different energy modeling software programs exist, some of which are open access and other that must be purchased. The U.S. Department of Energy has a range of programs with varying capabilities that can be used to predict building energy consumption, such as: EnergyPlus whole building energy modeling , energy simulation and building performance Open Studiow hole building energy modeling using EnergyPlus and Radiance, suitable for buildings in the design process RadianceUsed for lighting, daylighting, and solar control design Auto Tunewhole building energy modeling calibrated with actual energy usage
32 Other programs with building energy modeling capabilities include: EQuest energy performance and building simulation REM/Rate residential building energy simulation VisualDOE energy performance and simulation Home Energy Saver Autodesk Green Building Studiobuilding information modeling and energy performance A more comprehensive list of programs can be found at the U.S DOEâ€™s Energy Efficiency and Renewable Energy Building Energy Software Tools Directory (USDOE) . Alternatives to these simulation soft ware tools include data mining, as described by Chou and Bui (2014). They discuss utilizing various artificial intelligence inference models to more accurately predict building heating and cooling loads than more traditional building energy software progr ams (Chou and Bui, 2014). More frequently, building energy modeling programs are being used in specific case studies and real life applications to aid in determini ng the best course of action to improve the efficiency of a building or series of buildings. It can be seen that there is a large variety of different programs to choose from, and each program has benefits and drawbacks based on their capabilities and functionality. Certain programs may be more appropriate and suitable depending on the needs of the user, but there seems to exist a wide array of options to meet these various needs. Even if energy modeling programs are not utilized in every situation, a number of case studies can still be examined to
33 make the ca se for the implementation of energy efficiency measures to reduce energy demand and consumption. Case Studies Building efficiency has been paid attention to increas ingly in the past several years, whether it is concerning an existing or newly designed building. Over the years, countless case studies have been published relating to both building types that report energy and monetary savings from either energy efficiency retrofitting or implementing energy efficiency measures from the outset of building design. In addition to this, numerous case studies have been undertaken in energy modeling to determine potential savings from efficiency upgrades. Ma et al (2012) summarize several previous energy modeling case studies where energy conservation measures range in complexity from replacing bulbs to implementing a green roof (p. 11). For instance, they cite a Canadian office building that was modeled in EnergyPlus to be retrofitted to implement heat recovery, daylighting, a boiler efficiency economizer, prehe at upgrade, and lighting load reduction, which found a potential for a 20% reduction in electricity demand, and a 27% average reduction in natural gas demand (Ma et al 2012). Energy modeling was performed on the Empire State building that determined a pot ential 38% reduction in energy use if window upgrades, insulated reflective barriers, daylighting, plug load reduction, chiller plant retrofit, air handler unit retrofit, demand control ventilation, and energy management were implemented in the building (M a et al 2012). Multiple studies found that improvements to a residential building shell (air sealing, insulation and window replacements) could save an average of 10% on energy costs in most locations (Ma et al 2012). Yet another study of an older residential home found
34 that adding roof, wall, foundation wall and floor insulation; air sealing and window and door replacements; installation of energy efficient appliances; and the adoption of renewable energy could be paid off in as little as 2 years, based on a life cycle energy analysis (Ma et al , 2012). Another study cited by Ma et al found that ceiling and wall insulation were cost effective in single family buildings studied, with savings ranging from 12 to 21% (Ma et al , 2012). Simply replacing traditional incandescent lightbulbs with higher efficiency compact fluorescent bulbs (CFLâ€™ s) in the entire residential sector would have the potential to save $37 million with 25% of residential bulb replacement, $74 million with a 50% replacement rate, and $111 million with a 75% replacement rate (Ma et al, 2012). Yet another study cited by Ma et al found that â€œcooling load reductions for noninsulated buildings and insulated buildings with green roofs installed were 1549% and 633%, compared to that without using the green roof, respectivelyâ€ (p. 11). Ramesh et al, 2010 also list useful case study information that reports reduction in operational energy consumption associated with various combinations of passive and active energ y savings measures when applied to residential and commercial buildings (p. 7). For instance, one study found a 20% reduction in operating energy requirements for a residential building in Switzerland that was heavily insulated in the exterior walls, atti c and slab, and had a geothermal heat pump and heat recovery system (Ramesh et al, 2010). Another study cited found a 21% reduction in operating energy by a residential building in Norway that used an exhaust air heat pump that preheated ventilation air a nd hot water. The same study by Ramesh et al (2010) found that even with the implementation of active and passive energy efficiency improvements, office
35 buildings always consume more energy than residential buildings, which is to be expected due to their l arger size and higher occupancy rates (p. 89). These are just a few of the hundreds, potentially thousands of case studies that exist that serve as a testament to the benefits of building efficiency improvements. This type of information has been studied by governmental and private organizations to develop a case for enhancing building efficiency, in addition to independent studies performed by these organizations. A recent report by the Energy Information Administration indicates that improvements in building energy efficiency have â€œreduced energy intensity enough to offset more than 70% of the growth in both the number of households and the size of dwellingsâ€ (EIA, 2015). This has allowed for the decrease in household energy consumption. They have also found that the percentage of energy consumption used by heating and cooling has decreased in recent years, which is attributable to improvement i n equipment efficiency and the installation of better insulation and windows (EIA, 2013). Even in the face of these case studies that provide evidence that building efficiency improvements are a good way to reduce energy consumption and save money, there are still some complexities associated with and disagreements about building efficiency improvement. Complexities Involved with Improving Building Efficiency and Alternate Points of View According to Ma et al, many different elements impact building retrofits including â€œretrofit technologies, policies and regulations, client resources and expectations,
36 building specific information, human factors, and other uncertainty factorsâ€ (Ma et al 2012: p. 3 ). These factors can contribute to o r detract from the success or ease of improving building efficiency in different ways, but they all interact during the process of implementing efficiency measures. For example, retrofit technologies, or as Ma et al (2012) refer to them, energy conservati on measures (ECMs), are key to reducing energy consumption in buildings, but can be costly and c omplex to install or implement. It is true that not all buildings will benefit from the implementation of efficiency components; the effectiveness of these ins tallations varies depending on the building type, how it is used and by whom, where it is located, what it is located near, and myriad other factors. It is not unheard of for a building energy simulation to model low savings based on any number of factors , which would render the installation of efficiency measures nonfeasible as far as a financial payback goes. However, improving the efficiency a building, for example its shell, reduces energy transfer between the conditioned interior and the exterior in heating and cooling months and inherently improves comfort in the building. This may not always be measureable in energy saved in every case, but occupant comfort would still be improved. This is much the same situation as window replacement s go. High efficiency windows are expensive, and if all the buildingâ€™s windows are replaced, there is generally a high price tag. Energy and monetary savings from window replacements are typically not high at all according to building science professionals, however highly efficient windows suitable for a buildingâ€™s particular climate can improve comfort in the building. So while efficiency measures may not always achieve desired energy savings or provide a
37 reasonable payback period in every situation, they will improve occupant comfort as long as they are installed correctly. Another complexity related to building energy performance relates to building life cycle energy consumption. Diffe rent building life cycle analyses have come to the conclusion that the â€œtotal e nergy needed in a low energy building may be even higher than in a building with a higher amount of energy needed for operationbecause large amounts of energy are needed for production and maintenance of the technical equipmentâ€ (Thormark, 2005: p. 1 ). In a related finding, Ramesh et al (2010) found that low energy buildings tend to consume less energy than net zero buildings in the overall lifecycle of the building. This is due to the fact that an increase in the embodied energy due to energy saving meas ures in low energy buildings is small compared to its decrease in operating energy, while net zero or self sufficient buildings have high embodied energy that exceeds the life cycle energy of some low energy buildings (Ramesh et al, 2010). They indicate that â€œthere is a limit for life cycle energy savings through reduction in operation energy by installing complex and energy intensive technical installationsâ€ (Ramesh et al, 2010 : p. 7 ). There are clearly tradeoffs when it comes to considering building energy efficiency, and it seems wise to consider each building individually on a caseby case basis to determine the best course of action for the particular building in question, keeping in mind the precedents set by other building efficiency studies. Beyo nd resear chers in the building performance field who may have found issues or alternative points pertaining to building efficiency, opponents of building efficiency may exist for a variety of reasons. For instance, people with a vested inter est
38 in fossil fuels, such as fossil fuel company executives or employees , lobbying groups or certain politicians, may not necessarily want to see reductions in energy consumption. Efficient buildings consume less fuel by virtue of their efficiency; using less natural gas, propane or fuel oil for space heating, cooking or clothes drying. These buildings also use less electricity, which as was discussed earlier is largely produced by coal fired power plants. A widespread reduction in the use of these fossil fuels would mean less business for these companies, and could do serious damage to their pr ofits unless they changed their business model or product. Other potential opponents of building efficiency are utility companies that would also see fewer profits if less electricity, gas, oil, and propane are being consumed. It is important to note, h owever, that there are many state governments in the U.S. that have passed efficiency acts which require utilities to reduce their energy production. For instance, the EmPOWER Maryland Energy Efficiency Act of 2008 set a 15% target reduction in electricit y consumption and peak demand from a 2007 baseline to be reached by the year 2015 (MEA, 2013). Utility companies must comply with this directive and in this case set up home performance rebate programs. It is also possible that citizens or businesses could be mistrustful of building efficiency since it can be closely linked with the environmental movement, which some people tend to oppose for various reasons . It is true that many involved with building performance possess a concern for environmental iss ues associated with overconsumption of energy in buildings, but b uilding efficiency has ample room to stand on its own because of its potential to save building owners money. Even if a person
39 does not have any environmental concerns, they could still be i nclined to improve their buildingâ€™s efficiency if it meant they would pay less to operate it . Summary In conclusion, the face of the built environment has changed drastically over time as humanity has changed. Technological advances hav e rendered buildings less sustainable that they were in the past, especially when it comes to day to day operational energy consumption. R esidents of the United States have generally grown accustomed to a lifestyle that , with the advent of electricity and mechanical air conditioning, doesnâ€™t fully support living in truly sustainable buildings , as renewable energy systems are not yet a commonplace characteristic of American buildings . A great deal of research has been conducted that shows that buildings consume a sub stantial amount of energy that comes from nonrenewable fossil fuels, and i s damaging to the environment. However, t he efficiency of buildings can be improved to reduce their consumption of energy, and can be achieved by different technologies and measures applied to individual buildings. These efficiency measures also improve comfort of occupants, and reduce operational costs in the form of energy bills . Energy modeling exists to model theoretical energy efficiency upgraes and determine the best expendit ure of money to save the most amount of energy. Countless case studies have been performed with varying results, some more successful in reducing energy consumption than others , but generally supporting the trend that building efficiency can be improved by implementing various efficiency measures . However, there will seemingly always be some interest groups that oppose energy improvements on different grounds, claiming that these efforts will hurt the economy to promote science
40 that has not been indisputa bly proven. Case studies can make an impact on our future efficiency goals by demonstrating to governments that building efficiency can make a difference in energy consumption t hroughout the country. This could influence governments to further develop incentives programs to help people pay for efficiency upgrades, which could reduce our overall energy cosumption as a nation. If the overarching goal that we wish to achieve is sustainability, increasing the efficiency of buildings is a step in the right di rection.
41 CHAPTER 3 RESEARCH METHODOLOGY The purpose of this research was to determine the impacts of various energy efficiency measures, techniques and technologies on four theoretical buildings to examine the impacts of the implementation of efficiency measures in commercial and residential buildings. T he most commonly used energy efficiency measures were identified and documented . Next , simulations were conducted using two established energy modeling software program s that modeled t he efficiency measures in various combinations to determine their potential for energy savings in specific building scenarios in one geographic location. The anticipated outcome was a contribution to the existing body of work that has studie d the addition of energy efficiency upgrades to new and existing residential and commercial buildings. The study synthesizes secondary sources to identify efficiency measures and simulates four theoretical buildings (one existing residential, one new residential, one existing commercial and one new commercial ) located in the Washington, D.C. area before and after energy efficiency measures are implemented. Noresco LLCâ€™s REM/ Rate 14 software and the Quick Energy Simulation Tool (eQuest) sponsored by t he Department of Energy were utilized for energy modeling . These buildings were chosen to give a broader range of results applicable to more scenarios . The location of the buildings was chosen because this region experiences both cold winters and hot sum mers and so there are noticeable benefits to improving building efficiency in many instances . The population of Washington, D.C. and the surrounding metropolitan areas is also quite substantial and continues to grow and the area contains many older, ineff icient buildings that could benefit from energy efficiency retrofits. Also, t o
42 accommodate a growing population and more affluent demographic, new buildings are continuously being developed, though not always with efficiency in mind. The REM/ Rate and eQ uest program s were chosen because of their capabilitie s, reliability and because they are well known and widely used among building efficiency practitioners for residential and commercial energy modeling, respectively . The data resulting from each simulat ion is output in energy consumption/savings, as well as monetary savings, which assisted in the ease of analyzing the data. Energy efficiency falls into several categories such as building orientation; building materials; envelope /shell ; heating, ventilation and air conditioning (HVAC) equipment and distribution systems; major appliances; lighting; and roofing. The new buildings were modeled largely to determine the effect that building orientation had on the performance of the buildings, as well as to provide quantitative energy usage numbers for highefficiency new construction buildings that could be useful for some prospective building owners to reference. Existing Residential Energy Modeling The existing residential building was modeled first using the REM/ Rate software (REM/Rate). A new scenario was created and Washington, D.C. was selected as the buildingâ€™s location, which automatically generated heating degree and cooling degree days of 4459 and 10034, respectively. The International Ener gy Conservation Code climate zone, ASHRAE factor, and design heating and cooling temperatures were also automatically generated based on the building location , which can be seen in Appendix I. The cost per kilowatt hour (kWh) of electricity and cost per therm of natural gas was manually input based on the average price of electricity and gas found for
43 Washington, D.C., which was $0.14/kWh, and $1.25 per therm (BLS, 2015) . Default electric and gas providers were selected, as can be seen in Appendix I . Th e conditioned area was manually set at 2,500 square feet (SF) (40 feet x 62.50 feet) with 8.5 foot ceilings, for a total conditioned volume of 21,250 cubic feet. The year built was set to 1965, and the building type selected was single family detached, one floor above grade, three bedrooms, with a slab foundation. These characteristics were chosen based off of commonly seen residential buildings of an average size and age. More information can be found on this in Chapter 6. The longer sides of the building were modeled as facing east and west, while the shorter sides faced north and south. This undesirable orientation was chosen so that energy savings could be attributed to the efficiency measures alone as they are coupled with a poor orientation, instead of promoting potential synergistic effects between efficiency measures and a more optimal orientation. Images of all the parameters set in this program can be found in the Appendix section of this report. This includes the next several categories of t he building characteristics, which were entered in order of appearance in REM/ Rate : slab floor properties summary, floor properties summary, abovegrade wall properties summary, window and glass door properties summary, door properties summary, ceiling pr operties summary, mechanical equipment properties summary, duct system selector, whole house infiltration, lights and appliances audit summary and drywall thickness. Skylights, solar systems, and sunspaces were excluded from the building model even though they appear as options in the modeling program. The â€œMandatory Requirementsâ€ and â€œDOE Zero Energy Ready Homeâ€ sections were also left blank as they are not pertinent to the aim of this particular energy model. The parameters for the
44 building were set ov erall to imply low levels of energy efficiency, which is reflective of a subsection of the existing residential housing stock throughout the country , as well as in the Washington, D.C. area. After these parameters were input, an energy analysis was run to determine design loads, annual loads, annual consumption and annual energy costs for the building . The energy consumption resu lts from this baseline model were then recorded and compared to the models run after efficiency improvements were modeled. The improvement analysis was run after pricing research was conducted to determine appropriate cost s of implementing each improvement , combining capital and labor costs . The prices used for air sealing and insulation measures were obtained from a residential energy auditing company located in the metropolitan D.C. area ( Ecobeco LLC, personal communication, 2015) . The prices used for windows, doors, and appliances were based off of pricing found on the internet. T he following efficiency improvements were add ed to the improvements library in REM/ Rate to be run: R 7 added to the slab perimeter at $1.30 per linear foot (Ecobeco LLC, personal communication, 2015). R 19 added underneath the floor at $1.50 per square foot (Ecobeco LLC, personal communication, 2015). R 22 added to the exterior wall at $3.60 per square foot (Ecobeco LLC, personal communication, 2015). Double pane, low emissivity, argon filled, vinyl framed windows installed at $200 per unit (Loweâ€™s, n.d).
45 Steel, poly urethanecore exterior doors with storms installed at $400 each (Loweâ€™s, n.d). R 30 block insulation added to the attic at $1.60 per square foot (Ecobeco LLC, personal communication, 2015). 94 AFUE gas furnace installed for $5,000 (Home Depot, n.d). 14 S EER air conditioning unit installed for $3,000 (Home Depot, n.d). Demand (tankless) water heater installed for $1,300 (Home Depot, n.d). Programmable thermostat installed for $100 (Home Depot, n.d). Duct insulation for $300 (Ecobeco LLC, personal communic ation, 2015). Duct sealing for $1,850 (Ecobeco LLC, personal communication, 2015). Whole house air sealing to a 30% reduction in air leakage for $1.10 per square foot (Ecobeco LLC, personal communication, 2015). High efficiency lighting for $10 per unit (Home Depot, 2015). High efficiency refrigerator for $1,200 (Loweâ€™s, n.d). High efficiency dishwasher for $1,000 (Loweâ€™s, n.d). Low energy ceiling fans for $200 each (Home Depot, n.d). High efficiency clothes washer and dryer for $2,000 (Loweâ€™s, n.d) . Reduction in plug loads These efficiency improvements were categorized and divided into various pac kages that were run separately. These v arieties of combinations of improvements we re modeled to give a wider range of potential retrofit options that c ould be applicable to different building owners, depending upon their interests or budgets:
46 The â€œt otal packageâ€ was run w ith all listed improvements included T he â€œbase packageâ€ was run with slab insulation, exterior door replacements, attic insulation, programmable thermostat installation, duct insulation, air sealing, high efficiency lighting, plug load improvements and ceiling fans The â€œshell packageâ€ included slab, floor, exterior wall and attic insulation, air sealing, and window and door replacement s The â€œappliances packageâ€ included heating, cooling and water heater replacements, programmable thermostat installation, duct insulation and sealing, high efficiency lighting installation, and refrigerator, dishwasher, ceiling fan, washer/dryer and plug l oad replacements. These various scenarios were examined and analyzed, as will be discussed in the â€œFindings and Discussionâ€ section of this report. After this portion of energy modeling was completed, the new construction/new design residential building was modeled. New Construction/New Design Residential Building Energy Modeling Similarly to the existing residential building, REM/ Rate was used to model a new construction/new design residential building. Basic inputs were kept constant to the existing residential building, such as location, size, dimensions and volume, electricity and gas prices, and other primary characteristics , which can be found in the previous section of this chapter . The building characteristic inputs that varied fro m the last scenario were efficiency related; this building was modeled to exist at a higher state of efficiency with no need for any efficiency improvements . The long sides of the building were oriented to face south and north, the highest possible insulation and
47 ef ficiency values were selected for the slab, floor, abovegrade walls, exterior doors, attic, mechanical HVAC equipment, duct system and major appliances to reflect the more standard ways in which a building could be constructed to be more energy efficient. The whole house infiltration was set to 80% of the building airflow standard (BAS), making this building relatively tight without causing potential air quality issues . The windows selected were also the highest performance that the software has availabl e, and the orientation of the windows was set so that the majority of the windows were on the southern wall, with comparatively minimal glazing on the northern, eastern and western walls ; the building was oriented to operate passively . Overhangs were input above the southern windows to prevent solar heat gain in the winter, and a large overhang, likely in the form of a porch, was modeled as existing on the western side of the building. A thermal mass floor was also modeled as existing in the southern port ion of the home. Screenshots of all the inputs from this scenario can be found in Appendix II. A usage analysis was then performed to determine the annual loads, consumption and energy costs, which can be found in the Results chapter of this report. Variations on the efficiency parameters were run next to provide alternative scenarios for savings comparisons and to determine which elements, if any, can be optimized or should be minimized in this particular scenario in this geographic location. In the se additional scenarios, most elements were kept constant and certain characteristics were changed to determine their impact on energy savings. The characteristics that were changed in their own individual scenarios while keeping the original inputs the s ame are as follows:
48 Window orientations were altered in additional scenarios, keeping all other parameters the same as they were originally set : o South facing Southeast and Southwest facing, respectively o North facing Northwest and Northeast facing, res pectively o East facing Northeast and Northwest facing, respectively o West facing Southwest and Southeast facing, respectively Window amounts were altered by changing the southernwall glazing whi le keeping glazing on the other windows and all other parameters constant: o 12 Southfacing windows 4 Southfacing windows (10% of wall area) o 12 Southfacing windows 8 Southfacing windows (20% of wall area) o 12 Southfacing windows 16 Southfacing windows (41% of wall area) o 12 Southfacing windows 20 Southfacing windows (51% of wall area) o 12 Southfacing windows 24 Southfacing windows (61% of wall area) HVAC systems were altered while keeping all other parameters the same as they were initially set: o H i gh efficiency furnace and AC 4 ton Geothermal system o High efficiency furnace and AC I ntegrated space/water heating These results were then analyzed; t he Findings, Analysis and Discussion chapter shows the results from these various scenarios, and provides a discussion of the implic ations of the findings. Existing Commercial Building Energy Modeling Following the modeling of the new construction residential building, a similar process was completed in order to model energy savings on an existing commercial
49 building. The Department of Energy sponsored eQUEST (Quick Energy Simulation Tool) was utilized in this portion of the process since REM/ Rate is not designed for commercial building applications . The program was first downloaded from http://www.doe2.com/equest/ and set up on th e computer. A new scenario was created using the eQUEST Schematic Design Wizard; the building was modeled as a standalone, 25,000 square foot twostory office building in Washington, D.C. The building was oriented with the longer sides facing east and w est to mimic poor energy performance in a worst case scenario, just like the existing residential building . All applicable building inputs were set as detailed in Appendix III. Poor efficiency inputs were selected for existing roof, wall, and floor insulation, and inefficient windows were modeled as existing. No window shading was modeled as existing. Building occupancy was set, as well as HVAC system characteristics and control settings and water heating characteristics. The baseline scenario was saved and the building was completed in eQUEST. Next, energy efficiency measures were created in the available categories of building envelope (roof ins ulation, exterior wall insulation, ground floor insulation, window glass type and shading) , daylighting, thermostat management, HVAC efficiency, and water heater efficiency. The highest available efficiency options were selected to be run as improvements to the existing building in each of these categories, and an impr ovement analysis was then run to determine the new building energy consumption after the modeled installation of the energy efficiency improvement measures, and the results were compared with the baseline results. eQUEST generated a series of reports outlining the results of the analysis, which will be discussed in the Fi ndings chapter of this report.
50 New Construction Commercial Building Lastly, eQUEST was again utilized to model a new constr uction commercial building. The same standard building characteristics were input as the existing commercial building; Washington, D.C. was set as the location of a standalone, 25,000 square foot twostory office building with a slab foundation. LEED NC (new construction) compliance analysis was performed on the new commercial building to ensure that a specific level of efficiency was achieved. The new commercial building was modeled with the longer sides facing south and north to determine the impact o f orientation on building performance. In this scenario, the building was modeled as having high efficiency components such as insulation, windows and doors, and HVAC equipment. Efficient lighting was also modeled as existing in the new construction comm ercial building, but with the same lighting loads as the existing commercial structure . The thermostat set points was set the same as the existing commercial building --76 degrees Fahrenheit in the summer months and 70 degrees Fahrenheit in the winter months during occupancy . Appendix IV outlines the exact inputs that were utilized in this modeling scenario. The inputs stated in the appendix were saved and the model was run and output the estimated building energy and gas consumption. These results are noted and discussed in the Results and Analysis chapter of this report. In addition to this base building model, three different new construction commercial building scenarios were modeled, each having slight variations pertaining to window quantities a nd positions . This was undertaken to determine potential differences in building efficiency due to this variable and to see if any model attains better energy savings than the others. All of the alteration s to the bas e model involved
51 modeling a smaller percentage of windows taking up the north, east and west walls, while holding the number of windows on the s outhfacing wall constant. Energy simulations were run after each alteration to the base model, and the results will be discussed in a later chapter.
52 CHAPTER 4 SURVEY OF ENERGY EFFICIENCY MEASURES, TECHNIQUES AND TECHNOLOGIES Introduction and Intent The purpose of this chapter is to familiarize the reader with an assortment of energy efficiency measures, techniques and technologies for the four building types. Different categories of these measures will be presented for each building type, including building shell; heating, ventilation and air conditioning (HVAC); appliances; and lighting, as well as orientation and passive solar pr inciples for the new construction buildings. Many of the measures and technologies are applicable to different types of buildings, and will not be described in full in each pertinent section. Measures for existing residential buildings will be discussed f irst, followed by new construction residential, existing commercial and new construction commercial. The residential buildings referred to throughout this report are singlefamily, standalone buildings. Existing Residential Buildings Building Shell The building shell or envelope, which for the purposes of this project will be considered to be comprised of exterior walls, roofing, attic space, foundation, windows and exterior doors, is a critically important component when it comes to improving a building â€™s energy efficiency. Because of pressure differentials between the interior and exterior of a building, unconditioned outside air will leak into a building through its envelope as conditioned interior air leaks out. The transfer of conditioned and unconditioned air causes additional energy expenditure and utility costs as HVAC
53 systems are forced to condition even more outside air, and constitutes a waste of energy and money since air that was already conditioned is able to escape the building. An efficie nt building shell can vastly improve a buildingâ€™s efficiency, and can even reduce required HVAC capacity. Potential to improve the entire building envelope exists in the form of various efficiency measures and technol ogies. Roofing. According to Hall and Jones, roofing comprises 5070% of a buildingâ€™s total enclosure loads (Hall and Jones, 2010). Depending on the shading of the building, roofs receive a substantial amount of solar radiation and can directly contribute to its energy consumption (Hall and J ones, 2010). Many modern day traditional homes in the United States are roofed with dark er colored asphalt shingles that take in solar energy due to their high absorptive capacity. This solar energy is transferred through the roof and heats up the attic space below, which in turn transfers through often improperly sealed and insulated attic s (discussed in the coming sections) and into condi tioned living space. While this could provide heating benefits in many places in the winter months, this process leads to discomfort in hot summer months and requires a greater cooling energy expenditure in most U.S. cities that generally negates any heating benefits (US EPA, 2013) . Lighter colored roofs can be up to 70 degrees Fahrenheit cooler than darker roofs, and according to the Lawrence Berkeley National Lab and the Florida Solar Energy Center, light colored, reflective roofs reduce the need for cooling energy by up to 40% compared to darker roofs (Randolph, 2008). Roofing materials with high thermal emissivity (efficiency with which the roof emits thermal energy) and solar reflectance or albedo (ability to reflect away thermal energy) are able to release absorbed heat more easily and thus keep the roof ( and attic space beneath it ) as much
54 as 50 to 60 degrees Fahrenheit cooler than traditional roofs (US EPA, 2013) . According to the Energy Star website, roofs with high emissivity can help to reduce a buildingâ€™s cooling load; however benefits of highly emissive roofs are still being researched in many places since low emissivity helps to retain heat and can reduce heating loads (EnergyStar, n.d). There are a variety of roofing products that can reduce solar heat gain by virtue of their high emissivity and reflectance (albedo) levels. Existing roofs can be retrofi tted with specialized heat reflective materials, the roof can be covered with tile coating or other cooler materials, or the roof can be repl aced with a â€œcool roofâ€ ( DoE, n.d). Cool roof coatings or singleply membranes are generally applied to low sloped roofs found on commercial buildings and have a solar reflectance of 65% or higher and a thermal emittance of 90% or more (US EPA, 2013). Certain newer roofing materials that are lighter in color have also been developed for steepsloped roofs found more commonly on residential buildings, with solar reflectance values of 25 to 70%, depending on the color (US EPA, 2013). Cool colored metal roofing products have solar reflectance levels of 2090% (US EPA, 2013). The purpose of these roofing materials is to increase the overall solar reflectivity and thermal emissivity of the roof, reflecting and emitting as much infrared radiation as possible and reducing overall solar heat gain through absorption by virtue of the lighter color of the material (Randolph, 2008). However, energy savings associated with reflective roofing is dependent upon many factors, such as climate, insulation used, building location, duct placement, attic configuration and envelope efficiency (US EPA, 2013) . If the building envelope is highly efficient, it is not considered to be as beneficial to upgrade to a higher efficiency roof, since solar energy
55 absorbed by the roof would be blocked from entering conditioned space anyway through a well sealed and insulated attic ( Energy Star, n.d) . Efficient, reflective roofing can still, however, make a difference in reducing cooling needs overall , with average energy savings of 20% (US EPA, 2013) . Exterior Walls and Foundation. Exterior walls serve in conjunction with the roof as the other maj or barrier to outside air and encloses the conditioned space which comprises the building. Unconditioned air is able to enter conditioned space through the exterior walls through the processes of conduction (lack of adequate wall insulation) and infiltrat ion (through unsealed gaps and penetrations in the walls); the U.S. Department of Energy estimates that more than 1/3 of air infiltration occurs through the building envelope (DoE, n.d). Much like roofing, the material of the exterior walls plays a role i n the absorbance of heat which then transfers through the walls. Darker colored materials absorb more heat, while lighter colored materials absorb less, and there exists various exterior wall materials that can improve building efficiency. This will be d iscussed in the â€œNew Construction Residentialâ€ section. Where existing buildings are concerned, the most common energy efficiency improvements that can be made to exterior walls are air sealing and insulation. Exterior wall penetrations and other gaps that lead from the interior to exterior of a building can b e sealed to prevent energy leakage. Basement rim joists or sill plates are another source of air leakage that can be sealed from the interior to reduce air leaks. Exterior walls can also be insulated to combat energy transfer, reduce heating and cooling l oads, and improve comfort in buildings. Two of the most common types of insulation that are applied to an existing residential building are dense packed cellulose and spray
56 foam insulation. Exact methods of installing this insulation vary on a caseby ca se basis, but it is common to drill holes in exterior walls to fill them with dense packed cellulose. Spray foam is less commonly utilized in exterior walls of existing buildings, as it is generally (and most realistically) applied to unfinished walls , al though injectable spray foam can be performed (DOE, n.d) . Spray foam is generally always the more expensive type of insulation, but delivers high R values, is very effective when applied correctly, and acts as an air barrier that also seals gaps and crack s in exterior walls. Dense packed cellulose is not as effective as spray foam in terms of thermal efficiency , but is more feasible to install in homes that are not undergoing a major retrofit and is also much less expensive. Fiberglass batts are the most common type of existing exterior wall insulation in residential homes, but similarly to spray foam, cannot be installed in finished walls, is susceptible to moisture, and degrades over time as air leaks pass through the insulation, reducing its efficiency (DOE, n.d) . Where foundations are concerned, basement walls can be treated with insulation and air sealing as noted above. Basement rim joists, as mentioned earlier, generally need to be air sealed and insulated by using either spray foam insulation or fiberglass batts. Crawlspaces can either be enclosed by adding fiberglass batt or spray foam insulation or insulating foamboard to t he walls, or can be treated by installing insulation or foamboard to the ceiling; t his is determined on a caseby case basi s. Houses on a slab foundation can have the perimeter of the slab caulked and insulated to reduce energy transfer and save an estimated average of 1020% on heating bills (DOE, n.d) . Windows. Windows are an essential part of residential buildings, as they supply light and opportunities for ventilation. They also provide opportunities for solar heat
57 gain, which may be a positive attribute during cold winters, but which adversely impacts the performance of buildings in the summer. The U.S. DOE estimates that 10% of energy leakage in an existing residential building can be attributed to leakage through windows (DoE, n.d). This contributes to occupant discomfort and higher energy bills due to the loss of conditioned air and the requirement for the HVAC sys tem to condition additional air that leaks in from the outdoors. T wo main solutions exist for reducing air leakage through windows; treating the existing windows, and installing new, energy efficient windows. Existing windows can be improved in several different ways, the first of which is by the addition of storm windows. These provide an additional barrier to the exterior of the home and help to prevent air leakage (DOE, n.d). Window caulking can be used for cracks, gaps, or joints around the window less than inch wide that allow for air leakage to occur (DoE, n.d ). Weatherstripping can be used on the moving components of windows to tighten the seal around the window . Window treatments can also be installed either on the interior or exterior of th e building to help block sunlight from entering, or prevent energy leakage. Exterior awnings are installed to shade windows and can, according to the U.S. Department of Energy, â€œreduce solar heat gain in the summer by up to 65% on southfacing windows and 77% on west facing windowsâ€ (DoE, n.d). Window blinds also block sunlight from entering the home; products with high reflectivity have been found to reduce summer solar heat gain by up to 45% (DoE, n.d). Curtains and drapes can also be effective at blocking direct solar gain as well as preventing heat loss in the winter, reducing heat gain by up to 33% and reducing heat loss by around 10% (DoE, n.d). Other treatments of existing windows include window films and solar shades with
58 high reflectivity, insulated window panels (pop in shutters), window screens, shutters and shades, and roof overhangs. Treating the buildingâ€™s existing windows using the above methods is usually found to be more cost effective than all out window replacement and can make a difference in solar heat gain and interior comfort , but is not necessarily as effective as replacements in every situation. These improvements are likely to improve comf ort in individual rooms, but will likely not provide much in terms of energy and monetary savings. The other option to reducing energy leakage through windows is to replace them with high efficiency alternatives. Several different types of efficient windows are available for installation, with a variety of glazing and glass options. The best options for an individual building are dependent upon the climate in which the building is located, as shown in Figure 4.1 below . These different zones require varying performance criteria for windows, namely, the U factor and Solar Heat Gain Coefficient (SHGC). A windowâ€™s Ufactor is a measure of its thermal conductance, or the amount of thermal energy that is able to transfer through it ; how well it insulates (Randolph, 2008). Figure 4.1: Selecting Energy Efficiency by Climate Zone. Obtained from U.S. Department of Energy on June 6, 2015.
59 In effect, U factors measure â€œhow well a product prevents heat from entering or escaping a buildingâ€ (NFRC, 2012). Lower U factors are indicative of windows that are more effective insulators ( D OE, 2010 ). The SHGC is â€œa measure of the fraction of solar energy that hits the windows that is transmitted into the interior of the buildingâ€ (Randolph, 2008, p. 272). In other words, it measures how much solar heat is blocked from entering the building (NFRC, 2012). Lower SHGCâ€™s indicate windows that are more effectively blocking solar heat gain (DOE, 2010) . According to Randolph, higher SHGCâ€™s are a good quality for passive solar heating, however a balance must be struck to account for too much heat gain in summer months, depending on where the windows are being installed (Randolph, 2008). Figure 4.2 below demonstrates the variations in window characteristics that should be installed based on climate. Figure 4. 2: Window Characteristics for Different Climates. Obtained from the U.S. Department of Energy on June 6, 2015. Different types of windows employ different technologies and materials to attain varying U factors and SHGCâ€™s, which are appropriate in their own respective zones. Tinted glass windows work to absorb some of the incoming solar radiation and effectively reduce the SHGC, as well as glare (DoE, 2015). To lower the U value in these types of tinted windows, additional layers or selective coatings need to be added to the inner portion of the window. Insulated windows are windows that have more than one pane of glass, where the space in between panes is sealed and has an
60 insulating air space, ranging from double pane all the way up to quadruple paned windows. These spaces can also be filled with argon or krypton gas, which have a higher resistance to heat flow than air and improve the U factor (DoE, 2015). A number of different coatings can also be applied to the window glass, such as low emissivity coatings, reflective coatings, and spectrally selective coatings. Low emissivity coatings lower the U factor of the window, and come in varieties that control for the desired SHGC (DoE, 2015). Reflective coatings serve to limit the transmission of solar r adiation and in effect block more light than heat, and lower the SHGC (DoE, 2015). According to the U.S. Department of Energy, the use of reflective coatings is limited since the reduction in cooling load is sometimes offset by the fact that more electric ity is needed for lighting, since natural daylight is blocked by the reflective coating (DoE, 2015). Spectrally selective coatings are a form of low emissivity coating that filters out between 40 and 70% of solar heat but allow for the transmission of lig ht; they reflect solar heat while allowing visible light to enter, providing a low U factor and SHGC (DoE, 2015). The Department of Energy reports computer simulations that have found a 40% reduction in cooling requirements in new homes in hot climates th at have windows with spectrally selective coatings (DoE, 2015). Randolph reports the thermal resistance of a number of different types of windows, from the least efficient singlepaned windows (R 1) all the way up to â€œHeat Mirror Superâ€ windows (R 12.5) with quadruple panes, 3 kryptonfilled airspaces, two â€œheat mirrorsâ€ (layers of low emissivity coatings on polyester films suspended inside an insulating glass unit) (Randolph, 2008). This figure is shown on the following page, in Figure 4.3, and illustra tes the potential improvements that can be made from switching
61 from lower efficiency windows to hig h efficiency windows. Increasing the effective R value, which is the inverse of the U factor, of windows helps to strengthen the thermal envelope, or buildi ng shell, reducing energy leakage and thermal conduction. Figure 4. 3: Effective R values of various types of window treatments. Data obtained May 16, 2015 f rom Randolph, 2008, pg. 231. Window frames also have an impact on windowsâ€™ overall efficiency, especially its U f actor. Traditional aluminum or metal frames are good heat conductors, and do not contribute to window insulation. The U.S. Department of Energy notes that in order to improve the efficiency of aluminum or metal frames, a ther mal break or insulating plastic strip should be incorporated into it (DoE, 2015). Frames that have a better thermal resistance than aluminum or metal frames include fiberglass, vinyl and composite frames. Fiberglass frames and vinyl frames contain insulated air cavities, which improves the overall efficiency of the window, and composite frames , made of particleboard and laminated strand lumber are often found to have better thermal 0 2 4 6 8 10 12 14 Single Double Double Low-e Air Double Low-e Argon Double Low-e Krypton Heat Mirror Plus Heat Mirror Super 1 2 3.1 3.7 4.3 9.1 12.5 R value Window Type Example Center of Glass RValues of Various Glazing Types
62 properties than conventional wood frames (DoE, 2015 ). All window components need to be operating efficiently in order to reduce energy leakage through them. Retrofitting an existing residential building with new Energy Star rated windows can potentially lower residential energy bil ls by an average of 12% nationwide depending on climate, window orientation, and other factors ( Energy Star, n.d) and treating existing windows as noted above can improve comfort an d provide some energy savings. Since win dows can comprise a sizeable portion of the building shell and are known sources of air leakage, they should be improved in some way to prevent unnecessary energy leakage and strengthen the exterior thermal envelope of the building. Exterior Doors. Similarly to windows, exterior doors are a source of energy tra nsfer; the U.S. Department of Energy found that approximately 11% of air infiltration occurs through exterior doors (DoE, n.d), and old, inefficient doors can contribute to energy transfer through conduction as well. As with windows, ex terior doors can ei ther be treated as is to reduce this air leakage, or replaced with new, higher efficiency alternatives. The perimeter of exterior doors can be weatherstripped to help block energy transfer, and storm doors can be added to provide an additional layer between the interior and exterior. Storm doors with metal frames can have insulation in the frames, and highefficiency storm door s often employ low emissivity glazing (DoE, 2012). High efficiency replacement doors come in different varieties, but the most common, most energy efficient type are those with polyurethane foam insulation cores, which have R values up to R 6 (DoE, 2012). Inset windowpanes are typically glazed in
63 high efficiency doors and contain multiple panes to reduce heat flow through the wind ow (Energy Star, n.d). Highefficiency doors are also equipped with magnetic weatherstripping and generally have a tighter fit than the door it is replacing, which effectively reduces air infiltration (Energy Star, n.d). Sliding glass and patio doors can be improved by employing some of the same window improving techniques discussed above, like installing shades, light blocking drapes, and awnings. Improving the efficiency of exterior doors, like windows, fortifies the building shell and thermal envelope. Retrofits to exterior doors can improve the efficiency and comfort of residential buildings, and can be a cost effect ive â€œlow hanging fruitâ€ to begin the process of improving the homeâ€™s efficiency and performance. A ttic. Attics are among the most easily treatable unconditioned spaces in an existing residential building that provides noticeable efficiency and comfort benefits . As mentioned earlier, unconditioned outside air leaks into attics through the roof, which heats up and leaks into the adjacent co nditioned space. In order to optimize the energy efficiency of an ex isting residential building, attic s should be adequately air sealed and insulated to create an effective barrier between the living space and unconditioned attic. Any small openings or penetrations in the attic floor or living space ceiling are a source of air leakage and should be sealed, usually from the attic. These types of penetrations include plumbing, wiring, electrical and duct penetrations; recessed lights, ceiling fans and other fixtures; plumbing or duct chases that lead to lower levels of the home; framing voids; skylights; and dropped soffits, although more types of penetrations can be found in a typical attic. Once all gaps, cracks and penetrations in the attic floor are air sealed, the attic should be insulated. M any dif ferent types of insulation can be
64 applied to attics, including but not limited to spray foam (which effectively encapsulates the attic and does not necessitate air sealing the attic floor), loose fill fiberg lass, loose fill cellulose, rockwool and fiberglass batts. These different types of insulation offer their own advantages and disadvantages and t hey vary in terms of cost, effectiveness and environmental impact. Loose fill cellulose insulation is considered to have a relatively low environmental impact as it is typically made up of shredded paper products or other reclaimed materials, and has an R value of 3.6 per inch. Loose fill fiberglass and fiberglass batts have a lower R value at 3.14 per inch and are a skin and lung irritant, but are typically cheaper than loose fill cellulose. Spray foam insulation has a much higher R value at R 6 per inch, but has a very high embodied energy associated with it, as well as a much higher installation cost. The ty pe of insulation to be used in any given home depends upon the homeownerâ€™s desired use for the attic space, their budget, and any concerns they may have with health and safety risks of any given type of insulation. The optimal level of insulation to be installed varies depending on where the building in question is located, which can be seen in Figure 4.4 on the following page. Adequate ventilation in the attic is also key to keeping the space cooler and reducing opportunities for energy transfer. As evidenced by the preceding pages, there is a substantial amount of retrofit work that can be performed on the building shell alone that is typically found to have a sizeable benefit on the energy efficiency of the building. The next chapter of this report will include results from the energy modeling scenarios, and will describe the savings potential of many of the building shell efficiency measures described in this section.
65 Figure 4. 4 : Recommended insulation levels for retrofitting existing woodframed buildings. Obtained on May 14, 2015 from â€œRecommended Levels of Insulationâ€ Energy Star, n.d Heating, Ventilation and Air Conditioning (HVAC) Heating, Ventilation and Air Conditioning (HVAC) systems are critical for maintaining indoor air quality via ventilation and filtration and in providing thermal comfort in a building ( US EPA, 2012). As has been discussed earlier in this paper, HVAC systems use as much as half the energy consumed by residential buildings (Energy Star, n.d). While an efficient building shell is critical to keeping unconditioned air out of a building, an efficient heating, ventilat ion and air conditioning system is necessary to provide conditioned air to the buildin g with as little energy input as possible. Highly efficient HVAC systems are able to effectively heat and cool a residential building to the desired temperature, and an efficient building shell is able to retain that heated and cooled air for longer periods of time, which prevents excessive
66 strain on the HVAC system, keeps the house more comf ortable, and saves the occupant s money on additional heating and cooling costs. Depending on where the home is located, different fuel types may be used for space heating. It is more common for oil heating to be used in colder, more northern climates, while electricity powered heat pumps are seen more commonly in milder climates ( US EIA, n.d). Natural gas is implemented in approximately 50% of homes nationwide, as c an be seen in Figure 4.5 below ( US EIA, n.d). Figure 4. 5: Share of homes primary space heating fuel and Census Region, 2009. Obtained on May 16, 2015 from Energy Information Agency â€œToday in Energyâ€ n.d For the purposes of this study, natural gas powered furnaces and boilers, electric heat pumps, and central air conditioning units will be examined and discussed . To improve energy efficiency and reduce energy bills, each type of appliance in existing residential homes can either be cleaned and tune d up on a regular basis to optimize efficiency and performance, or replaced with a highefficiency appliance. It is also imperative for the building operator to check and repl ace the HVAC air filter r egular ly, as
67 these become clogged and reduce the effecti veness of the system, even potentially leading to system failure (Energy Star, 2009). It is possible to reduce HVAC usage by practicing energy conservation behaviors, like setting the buildingâ€™s thermostat(s) to 68 degrees in the winter and 78 degrees in the summer â€”an average of 121 pounds of carbon dioxide emissions a year can be saved for each degree a thermostat is adjusted (Bongiorno, 2008). Smaller energy efficiency measures such as smart or programmable thermostats adjust the temperature of the hous e throughout the course of the day, which can also cut down on energy consumption and costs. Natural Gas Furnaces. Furnaces are one means of providing space heating to buildings. Space heating is the single largest source of energy expenditure in most homes, accounting for 35% to 50% of energy bills and more than one billion tons of carbon dioxide in the United States annually (Amann, 2007). Furnaces in particular work, in short, by burning fuel (in this case, natural gas) in a combustion chamber, which heats a heat exchanger and transfers the heat to the air, which is brought into and circulated through the duct system via the furnace fan (Amann, 2007). The efficiency of furnaces is measured in terms of Annual Fuel Utilization Efficiency (AFUE), which ac counts for the â€œamount of useful heat produced per unit of input energyâ€ (Amann, 2007, p. 65). This accounts for all energy losses that occur by nature of the operation of the appliance. An 80 AFUE furnace indicates that 8 0% of the fuel used turns into heat for the home, while the other 20% is lost to inefficiencies and other energy expenditures not directly related to space heating (DoE, 2015). Over time, the efficiency of the appliance degrades if it is not properly maintained and tuned up. Regular m aintenance is recommended, as mentioned previously, including cleaning
68 and/or replacing the air filters, cleaning registers and keeping them clear of furniture and other obstructions, and checking/adjusting the duct dampers, which control heat flow to diff erent parts of the home (Amann, 2007). If a replacement furnace is desired, manufacturers have now reached efficiency levels of 97 AFUE, providing a much higher, more efficient fuel utilization than standard efficiency appliances (DoE, 2015). High efficiency furnaces also have variable speed motors, which are able to move at different speeds and better control the flow of heated air throughout the house. These motors require less energy input than standard motor s and improve heating efficiency (Turkel, 1 999). Consultations wi th HVAC professional s are beneficial to homeowners looking to upgrade their furnace, since many different efficiency technologies exist and are appropriate in some houses more than others. Boilers. Boilers operate similarly in many ways to furnaces, and the same efficiency rating is used to describe boilers (AFUE). The main difference between furnaces and boilers is that furnaces transfer heat through the air, while boilers distribute heat via water circulating through radiators, baseboards or other distribution devices in the house (Amann, 2007). Boilers also contain a combustion chamber where fuel is burned, but instead of heating air, water is heated, and instead of traveling through ducts, the water travels through pipes and int o radiators or other devices. These appliances should also be tuned up annually to optimize efficiency and performance, or replaced with a highefficiency alternative. Central Air Conditioners. Well over 75% of American homes have central air conditioners (ACâ€™s), and energy consumed by air conditioners accounts for around 5% of all electricity produced in the United States (Amann, 2007). It is estimated that
69 around 1015% of energy use in the average home is attributed to cooling systems (Randolph, 2008), but upgrading to highefficiency AC units, in conjunction with air sealing and insulation described in the previous section, can reduce cooling loads by 2050% (Amann, 2007). AC units work, in short, by pumping a refrigerant, which is capable of absorbing and releasing heat, through the various components of the AC system. Warm interior air blows across the indoor component of the AC unit and transfers its heat energy to the refrigerant, which effectively cools the air, and is then distributed throughou t the house through the duct system. The heat that was absorbed by the refrigerant is carried outside the house. Air conditioners essentially remove heat from the building and â€œexhaustâ€ it outside, which in turn cools the interior (Amann, 200 7 ). This pr ocess requires, as mentioned before, a significant amount of electricity, but high efficiency AC units have been and continue to be developed to reduce the required amount of electrical input while still effectively cooling the building. The efficiency o f AC units is measured in Seasonal Energy Efficiency Ratio (SEER), which is the result of the seasonal cooling output divided by the seasonal energy input (Amann, 2007). High efficiency units range up to 18 SEER, in comparison to older AC units with SEER ratings under 10 (Energy Star, 2015). Energy Star estimates that new, high efficiency AC units are more than 15% more efficient than new, standard efficiency models (Energy Star, 2015). If a new AC unit is installed, highly efficient units can improve comfort, while costing less to operate. It is strongly recommended, however, that the unit be appropriately sized to the building. If an AC unit is too small, it will not be able to adequately cool and dehumidify the space as needed; but if the unit is t oo large, it can short cycle and decrease the efficiency and life span of the appliance.
70 Existing central AC units that are not being replaced should be tuned up and cleaned regularly to optimize performance as described previously . Heat Pumps . Heat pum ps have the capability to heat and cool a building, and operate essentially the same way as an air conditioner. In the summer, heat pumps remove heat from the cooler interior and empty it to the hotter exterior; in winter, the process is reversed and they extract heat from outside air and empty it into the interior (Amann, 2007). Heat pumps work best in climates with milder winters, as mentioned earlier, where the outside air stays above a certain temperature in the winter. If the outdoor air gets cold e nough, there is not enough heat to extract from the air to bring inside, and the unit must run on auxiliary heating mode where heat is conducted via an electric strip, which is an energy intensive process (Amann, 2007). Heat pumps should also be tunedu p on a regular basis if they are not replaced with a high efficiency appliance. The efficiency of heat pumps is measured in Heating Season Performance Factor (HSPF) for the heating portion, and SEER again for cooling. HSPF is measured by the total heating output of a heat pump during a normal heating season, compared to the total electricity consumed during the same period of time ( Energy Star, 2007). As with SEER and AFUE, higher values indicate a higher efficiency appliance, and the highest efficiency heat pumps typically available range up to 10 HSPF/18 SEER. Energy Star estimates that high efficiency heat pumps are around 9% more efficient than new regular efficiency models (Energy Star, 2015). Ducts. A major part of the HVAC system is the distribution system, comprised of ducts that distribute air heated by furnaces and heat pumps and cooled by central air conditioning. Energy Star has found that about 20% of the conditioned air that moves
71 through the duct system is lost to unconditioned space bec ause of holes, gaps, leaks, and inadequately connected ducts ( Energy Star, 2009). This means that even if a buildingâ€™s HVAC appliances are highly efficient in theory, maximum efficiency cannot be achieved with a leaky distribution system. This leads to higher than necessary energy bills and discomfort, which can be avoided if the duct system is adequately sealed and insulated. Apparent holes and leakage sources in the ducts should be repaired as possible in accessible attic, garage and basement/crawlspac e ducts , wherever they are located. The duct system should also be inspected to ensure that the ducts are connected to the vents and registers where they meet the floors, walls, and ceilings. If there are leaks or disconnects, these should be fixed to im prove the performance of the duct system (Energy Star, 2009). Any ductwork that is crushed or impeded in any way should also be repaired. If the duct system is tested and still found to be leaky once the obvious problems with the ductwork have been fixed, wholesystem duct sealing can be undertaken to seal smaller duct leaks from the inside of the ducts themselves. D uct sealing has the benefit of reducing direct air leakage, and prevents conditioned air from being lost to unconditioned spaces. It is als o recommended that ducts in unconditioned spaces be insulated to levels of R 6 or g reater ( Energy Star, 2009). This helps reduce energy transfer through the ducts themselves, keeping conditioned air inside the ductwork so that it can be conveyed to the co nditioned interior of the building. A well sealed and insulated duct system is an important part of an efficiently functioning HVAC system, and should be considered in energy efficiency retrofits. Energy Recovery Ventilator. While not necessary in all homes, Energy Recovery Ventilators (ERVâ€™s) can be a necessary addition to homes that have
72 undergone a deep energy efficiency retrofit that has left the building very airtight. In this scenario, an inadequate amount of air changes between the interior and exterior of the building take place inside the building , which can lead to indoor air quality issues. ERVâ€™s work by bringing in fresh air while also exchanging heat between conditioned indoor air (exiting the house) and unconditioned outdoor air (entering the house) so that the air does not need to be re heated or cooled by the HVAC system (Amann, 2007). These systems can be expensive, so it is generally recommended that buildings not be air sealed below a certain threshold to avoid needing to install an ERV if possible. Applicable federal, state and local incentives exist for investing in highefficiency HVAC systems and overall building efficiency , which can be researched online through EnergyStar.gov, electric and gas utility websites, DSIREUSA.org, local websites and other sources . Appliances Most existing residential homes have a number of major appliances in continuous use that function to help meet the needs of the occupants. These appliances range from water heaters, to major appliances like refriger ators, dishwashers, clothes washers and dryers, down to televisions, laptops and smaller electrical devices. These appliances all together account for around 25 30% of an average residential buildingâ€™s energy demand (Randolph, 2008). They not only draw electricity in order to operate, but many of these older appliances emit latent heat that heats up the building, contributing unnecessarily to cooling loads in the summer months. It is possible to implement energy efficiency strategies when considering eac h of the appliances above, as well as replacement with higher efficiency, Energy Star rated products.
73 Water Heater. Water heating accounts for an average of 15% of the average householdâ€™s energy use (Energy Star, n.d). As can be seen in Figure 4. 6 below , water heaters are generally powered by natural gas or electricity, although oil and propane water heaters can be found as well . Figure 4. 6 : Water heating fuel by census division, 2005. Obtained on May 16, 2015 from Ryan, 2010 Water conservation is a simple and effective way of reducing energy consumption required by water heaters , especially when paired with the installation of an insulating tank wrap and insulating water pipe wrap on traditional storage tank water heaters . Le ss water needs to be heated if less is being consumed throughout the house, and insulating tank and pipe wrap keeps energy from transferring to the ambient air through the tank and water pipes , which prevents the system from needing to reheat water that has cooled down, also known as standby losses (Energy Star, n.d).
74 If an appliance upgrade is desired or needed by the homeowner, there are many different kinds of highefficiency water heaters that can be installed that use between 10 and 50% less energy t han regular efficiency models ( Energy Star, n.d). For instance, high efficiency storage tank units are available that use 14% less energy than regular efficiency storage models (Ryan, 2010). Condensing water heaters capture heat from the combustion process and utilize it, reducing energy loss and thus improving its efficiency. This type of water heater has been found to be 30% more efficient than conventional storage units (Ryan, 2010). Alternative water heater types are also available, including tankl ess or ondemand units. As implied by the name, these water heaters do not have a storage tank, which eliminates standby losses, and heats water as it is needed by the occupant. This type of water heater uses 30% less energy than regular storage tank wat er heaters, but is more expensive than other highefficiency models. Heat pump water heaters have an added benefit of being able to cool and dehumidify the space in which it is installed, and use 55% less energy than conventional storage water heaters (Ry an, 2010). Solar water heaters are also available and most beneficial f or buildings with high water usage, using up to 50% less energy than standard water heaters (Ryan, 2010). Refrigerator. Approximately 7% of the average homeâ€™s utility bill is spent on powering the refrigerator, which can be cut down in a nu mber of ways (Bongiorno, 2008). The evaporator coil on the back of the refrigerator should be kept clean to help improve the efficiency of the appliance. The temperature settings of the refrigerat or and freezer can be set to 3540 degrees Fahrenheit and 05 degrees Fahrenheit, respectively to reduce energy consumption . The refrigerator doors should also be
75 checked to make sure they properly seal shut and do not leak cooled interior air into the ki tchen. New, high efficiency refrigerators are also available that are around 10% more energy efficient than standardefficiency models because of better insulation and compressor technologies (Energy Star, n.d). Energy Star estimates that if all refrigerators sold in the U.S. were high efficiency Energy Star certified products, 8 billion pounds of greenhouse gas emissions could be prevented each year, which is equivalent to the emissions of 750,000 vehicles (Energy Star, n.d). Dishwasher. Older dishwashers use more energy and water than their newer, higher ef ficiency counterparts, but certain user behaviors can lower energy and water consumption by these appliances if repl acement is not an option. This includes turning off the drying cycle to save energy and running only full loads to cut back on energy and water use. High efficiency, Energy Star certified dishwashers are around 5% more energy efficient and 15% more water efficient than standard efficiency models ( Energy Star, n.d). Clothes Washer and Dryer. Clothes washers and dryers have become commonplace in homes in the United States, but they account for a significant amount of energy as well as water usage. Energy and water use associated with clothes washers can be reduced by using cold water to wash clothes, as well as running fuller loads to prevent water waste if settings on the appliance are limited. New highefficiency, front loading Energy Star certified clothes washers use 25% less energy and 40% less water than standard efficiency washer s, and Energy Star estimates that more than 19 billion pounds of greenhouse gas emissions could be prevented annually if all clothes washers purchased in the U.S. were high efficiency models (Energy Star, n.d).
76 Behavioral changes can be made to reduce energy consumed by clothes dryers as well. Air drying laundry instead of using the clothes dryer is an easy way of cutting down on energy consumption, as well as utilizing the moisturesensor option (if present) on the clothes dryer to shut off the appliance when it senses that clothes are dry (Bongiorno, 2008). Energy Star has also recently begun to certify highefficiency dryers which use 20% less energy than standard models and contain features like low heat settings, which saves energy even though the dr ying cycle is lengthened (Energy Star, n.d). Small Appliances. Although there are available Energy Star labels for many smaller household appliances like laptops and TVâ€™s, energy conservation can also be practiced when it comes to these appliances, which can account for up to 10% of a buildingâ€™s primary energy usage (Randolph, 2008). Unplugging appliances that have display lights when they are not in use can save on electricity, since the power cords still draw energy when they are not in use. One rule of thumb to follow is that if the appliance is warm, it is drawi ng electricity and can be unplugged when it is not needed. There are also â€œsmartâ€ power strips that can be used to regulate whether or not items plugged into it are drawi ng any electricity based on whether or not the â€œmainâ€ appliance also plugged into the power strip is turned on or off. Household appliances draw enough electricity (and some use enough water) to make a small but noticeable difference in a homeâ€™s energy consumption when they are used more efficiently or replaced with more efficient alternatives. There are other types of appliances not mentioned in this section that can be similarly managed to reduce electricity and water consumption.
77 Lighting Between 10 and 20% of a buildingâ€™s electricity usage goes to lighting (Randolph, 2008) , which is a necessary amenity that can be managed much more efficiently to reduce associated energy usage. Conservation can be practiced in any building by firstly turning out lights that are not needed and only turning lights on in rooms that are occupied. Ope ning up blinds and allowing daylight to enter during daytime hours can eliminate the need for artificial lighting until sunset, or until the occupant can no longer see easily. Because they operate by taking an electric current and heating a filament until it gets so hot it glows, traditional incandescent bulbs lose most of their energy to waste heat, which contributes to latent heat in buildings and can contribute to higher usage of air conditioning in the summer. Knowing this, turning off excess lights c an also help to save energy associated with HVAC usage. Light timers and motion sensors can also be installed in buildings , although this is usually a technique implemented in larger commercial buildings. Aside from practicing conservation, homeowners have the option to purchase alternative lightbulbs, which are much more efficient than traditional incandescent lightbulbs. Compact Fluorescent Lightbulbs (CFL). CFLâ€™s were the first successful, widely used alternative to incandescent bulbs. Electric current enters a tube inside the bulb which contains argon and small amounts of mercury vapor, which generates ultraviolet light (which we cannot see) that â€œexcitesâ€ the phosphor fluorescent coating on the interior of the tube (Energy Star, n.d). This then emit s visible light, and at much lower temperatures than incandescent bulbs. CFLâ€™s also use 2/3 less energy than incandescent bulbs , and last around 6 7 times longer (Bongiorno, 2008). CFLâ€™s cost
78 more initially than incandescent bulbs, but because of their lower energy requirements and longer life, have a low enough payback period to justify their use. Light Emitting Diodes (LED). LEDâ€™s are a very efficient form of lighting, wherein semiconductor devices produce visible light when an electrical current is r un through them (Energy Star, n.d). LED bulbs use a fraction of the energy that incandescent bulbs use, and even use less than CFLâ€™s; they use 68 watts of electricity to produce each unit of light, compared to 1315 watts for CFLâ€™s , and 60 watts for incandescent bulbs (Energy Star, n.d). LEDâ€™s last around 40 times longer than incandescent bulbs and 6 times longer than CFLâ€™s. Like CFLâ€™s, LEDâ€™s are presently much more expensive than other bulbs, but use substantially less energy than the other types of bulbs, and also last significantly longer, making them an entirely economically feasible option for a buildingâ€™s lighting needs. The preceding pages have outlined a variety of different efficiency measures, techniques and technologies which can be used in retrofitting an existing residential building to reduce energy consumption. The next section will detail similarly how the energy efficiency of a new construction residential building can be improved. New Construction Residential Buildings Nearly all the measures, techniques and technologies that were discussed in the â€œExisting Residentialâ€ section preceding this one apply to newly designed and constructed residential buildings. These repeating measures will be referenced in this section but their descriptions will not be discussed in detail again. H owever, many additional strategies can be implemented in new construction buildings that are not applicable to existing buildings that will be included in this section. Many of these
79 strategies embrace the concept of passive solar design, which can be much more easily controlled for in new construction buildings than existing ones because many passive elements require implementation at the outset of building design. Passive solar essentially allows for a buil ding to be heated up in the winter using sunlight, which passes through windows and other glazed openings to reduce the need for mechanical space heating requirements (Randolph, 2008 ). According to the Passive House Institute US, passive buildings incorporate an airtight envelope with continuous insulation, have high performance windows, heat and moisturerecovery ventilation, minimal space conditioning systems, and take advantage of and manage solar gain (PHIUS, n.d). Many of the subheadings in this sect ion will directly relate to passive solar design; namely orientation and many of the techniques discussed in the envelope/shell section. Orientation Optimal orientation of a newly designed building is key to maximizing benefits from passive solar principles, assuming that the designers and builders have control over this important attribute. Appropriate building orientation has the following benefits related to passive design: Control solar heat gain to maximize passive solar heating in the winter , while minimizing it in the summer (additional techniques to accomplishing this will be discussed in the â€œEnvelope/Shellâ€ section) Take advantage of prevailing breezes to reduce cooling requirements and improve ventilation in the building Assist with natu ral d aylighting to reduce electric lighting demands
80 Due to sun movement and angles of the sun throughout the year, it is most beneficial in the northern hemisphere to orient building s along the East West axis so that the sides of the building with the larg er area face North and South, and the sides with smaller areas face East and West (VA DMME, 2005). However, slight variation off the East West axis can be necessary to help capture prevailing breezes, which Randolph states should enter the building from an angle rather than directly to improve ventilation efficiency (Randolph, 2008). The East West orientation optimizes the ability of the building to capture solar heat in the winter, while minimizing solar heat gain in the summer. The larger sides of the building should face North and South because these areas are the most easily controlled for solar gains (as will be discussed in the coming pages), and the East and West facing walls should be minimized as they are exposed to direct morning and afternoon s unlight in the summer months (Randolph, 2008). Vegetation can also be utilized on the East and West sides of the building to minimize summer solar heat gains. These strategies (among others that will be discussed shortly) will help ensure passive solar heating through the Southfacing wall in the winter, when the sun rises in the southeast, travels low in the sky along the southern wall, and sets in the southwest, and minimize solar heat gain in the summer, when the sun rises in the northeast, travels hig her in the sky, and sets in the northwest, as seen in Figure 4.7 on the following page. Building Envelope/Shell The envelope of a new construction residential building can be designed and built to reduce energy consumption by utilizing many of the same strategies as in the
81 Figure 4. 7 : Optimal orientation of a building to utilize passive solar benefits. Obtained on May 17 2015 from Randolph, 2008, p. 271. â€œExisting Residentialâ€ section, but also has greater potential for energy savings based on the fact that the building is being constructed from scratch, as opposed to retrofitted. The driving principle behind an efficient building shell remains the sameâ€” a better insulated, less leaky shell improves comfort in the home by retaining conditioned air for longer, while at the same time reducing the need for mechanical heating and cooling, which saves energy and money (VA DMME, 2005). Coupled with passive solar benefits provided largely by the orientation of the building, an efficient shell is able to retain solar heat in the winter, reducing the need for mechanical space heating, and keep out solar heat gain in the summer, reducing the need for air conditioning. Roofing. The same efficient roofing products as were outlined in the â€œExisting Residentialâ€ section can be installed on newly constructed buildings as well; this discussion started on page 47. Because new construction homes can be customized as desired, there are alternative options to traditional and high efficiency traditional roofs, namely living, vegetated or green roofs. Green roo fs can be incorporated onto flatter low sloped roofs which can be chosen for a new construction building , and have a number of benefits. The first, and most relevant to the purposes of this research project, is reduced heating and cooling costs. Green roofs in essence provide an
82 additional layer of insulation, provide shade and remove heat from the surrounding air through evapotranspiration ( EPA, 2013). This not only reduces the temperature of the roof, reducing heat transfer into the attic and in turn, into conditioned space, but also reduces the temperature of the surrounding air as well. According to the EPA, the surface temperature of a green roof on hot summer days can actually be lower than the ambient air temperature (EPA, 2013). This coupled with the fact that the plants on the roof serve as an a dditional layer of insulation means that less energy is needed to heat and cool the bui lding. A dditional benefits to green roofs include reduction of stormwater runoff by providi ng rainwater storage, improved air quality and provision for occupant health and comfort. Exterior Walls/Foundation. Newly constructed homes have the advantage of being air sealed and insulated as part of the construction process, which means that many of the air sealing and insulation options discussed in the â€œExisting Buildingâ€ section can be more easily implemented in new buildings. Refer to the previous section for more i nformation on this. Other materials c an also be implemented in new construction buildings to improve the efficiency of the exterior walls and foundation. Str uctural Insulated Panels (SIPs) are one such material that can be used to construct an entire building. SIPs are generally two plywood panels with a layer of insulating foam in between, and have the advantage of being relatively air tight with built in in sulation. SIPs have been found to improve energy savings by 1214% (DOE, n.d). Insulating concrete forms are another efficient building material, wherein concrete is poured between two insulating layers. This building material is also capable of providi ng energy savings because it is air tight and provides excellent insulation, much
83 like SIPs (DOE, n.d) . Vacuum Insulated Panels (VIPs) are yet another type of efficient material that may become available in the coming years for building construction, made up of an enclosed core panel in an airtight envelope to reduce heat loss ( US GSA , 2014). Oak Ridge National Laboratory has found that VIPs can have an insulation value up to R 50 and can reach 810% energy savings when applied as roofing (US GSA , 2014). Another type of energy efficient building material is e arth walls, which are essentially bricks or walls made of earth, often incorporating straw and other sustainable materials like sheepâ€™s wool (Goodhew, 2005). Earth walls have also been found to have excellent insulating capabilities, and harken back to earlier methods of building construction throughout the world. This and other types of building materials are also good examples of thermal massing, which is another important principle of passive solar design (VA DMME, 2005) . Thermal massing can take the form of a wall or flooring that is made of tile, concrete, earth, water or other dense materials that absorbs excess heat in the daytime, preventing the building from heating up too much in the winter, and releasing it to the interior space at night as the building starts to cool down (Randolph , 2008). Appropriate amounts of thermal massing need to be implemented in conjunction with the amount of southfacing windows that have been installed to take advantage of solar heat gain (Randolph, 2008). Thermal massing also needs to be incorporated appropriately with the passive design elements of the building. For instance, if a â€œdirect gainâ€ passive solar system is implemented, thermal massing just needs to be installed in adequate amounts as appropriate to walls and flooring to store excess heat entering through southfacing glass. Thermal mass walls can also be placed directly behind the windows
84 with an air gap, and slows down the time that it takes for solar heat to radiate into the conditioned space (Randolph, 2008 ). The â€œsunspaceâ€ approach to passive heating depends on having an attached greenhouse, or sunspace, with thermal massing incorporated to separate the conditioned space from the sunspace, as well as within the sunspace itself (Randolph, 2008). It can be seen that new construction buildings have a great deal of opportunities to ensure efficient exterior walls that existing buildings do not have without ex tensive renovation and retrofit . Inn ovative materials and design ideas can be incorporated and carried out in the construction of these buildings, provided they are financially feasible and properly designed from the outset of the process. Attic. Se e attic section. Windows. Windows play an integral role in the ability of a new construction house to operate using passive solar principles. As discussed in the orientation section, in the Northern hemisphere southfacing walls receive more solar insolation in cold winter months than east and west facing walls, and less solar insolation than east and west facing walls in hot summer months (Randolph, 2008). Walls and windows facing e ast and w est, in contrast, are exposed to nearly direct sunlight in summer mornings and afternoons and cannot be easily shaded with overhangs (Randolph, 2008). As such, a principle feature of passive solar design is to maximize glazing on the southfacing walls to a feasible extent for each individual project, balancing this with appropriate thermal massing (VA DMME, 2005) . This will increase and help optimize passive heating in the winter, reducing energy consumption by space heating appliances. In order to combat solar heat gain through the southfacing windows in the
85 summer, overhangs can be installed above the w indows to shade them from the higher angled summer sun. Appropriate types of glazing should also be implementedâ€” for passive solar houses, windows with high SHGC that are doubleglazed will be more beneficial as they attain greater solar gains than thermal losses in the winter (Randolph, 2008). The appropriateness of different glazing types will depend on the climate the building is located inâ€”low emissivity windows with high SHGCâ€™s, as just mentioned, are appropriate for passive heating in northern climates, however â€œsouthern low eâ€ windows have low SHGCâ€™s and are typically more appropriate in milder climates that emphasize summer cooling (Amann, 2007). These varying, climatedependent requirements can be balanced out by implementing overhangs and shading or implementing fewer windows, to name a few examples. See the previous windows section for more detailed information about window types; this information is also applicable in this section. Doors. See the exteri or doors section. The envelope of new designnew construction residential building s can be designed and built to operate more efficiently by implementing passive solar design (orient the house properly, optimize shell efficiency, implement southfacing windows, install overhangs, incorporate t hermal mass) and by utilizing efficient, energy saving materials (green roofs and efficient wall materials). These two features of new design buildings provide advantages that cannot be provided to existing buildings, and can enhance the energy efficiency of the building beyond what can be achieved in older, existing buildings. However, it should be noted that the use of passive techniques like types, numbers, and placement of windows coupled with thermal massing vary in
86 appropriateness depending on the building location and need to be individually designed for each specific building. This section serves to provide information about these techniques, but does not provide guidance on how and in what circumstanc es they should be implemented. Heating, Venti lation and Air Conditioning (HVAC) Please refer to the previous HVAC section for a full discussion of the different HVAC measures and techniques that apply to both existing as well as new construction residential buildings. These include behavioral changes like setting thermostats to more efficient temperatures, and installing new, high efficiency HVAC appliances. Geothermal Heat Pump. Geothermal heat pumps, or groundsource heat pumps, can be a feasible alternative to traditional HVAC systems in cases where a site is already in need of excavation, such as in a newly constructed sit e. These appliances operate the same w ay as heat pumps ( see â€œHeat Pumpsâ€ in the previous HVAC section) but instead of relying on outdoor air for heat transfer, utilize heat from underground, where temperatures are more stable throughout the year (Amann, 2 007). Geothermal heat pumps are much more efficient than heat pumps at extracting heat, operating between 2545% more efficiently than new air source (traditional) heat pumps (Amann, 2007). However, geothermal systems are more expensive to install and can be costly to maintain. Appliances See the previous appliances section for a discussion of home appliances that apply to both existing and new construction residential buildings.
87 Lighting The same conservation methods and high efficiency products can be implemented in new construction buildings as in existing buildings; for a full discus sion, see the previous lighting section. New construction buildings also have the advantage of being designed to bring in natural daylight in ways that are not necessar ily easily implemented in existing buildings due to aesthetics and difficult or tedious retrofit installations. Natural daylight can be brought into new construction buildings via mirror ducts, light shelves, and light pipes. Mirror ducts utilize highly reflective ducts to bring natural light into an interior space without the use of an external power source or mechanical parts (BCA, 2010). Collectors placed outside the building capture daylight, which is â€œchanneled into horizontal reflective ducts and exits through ceiling apertures above the userâ€ (BCA, 2010). Exterior light shelves are highly reflective surfaces that are capable of reflecting sunlight into interior rooms ( BCA, 2010). They also have the added benefit of shading windows against direct solar insolation. Light pipes are pipes that extend from the buildingâ€™s roof to the interior of a room, and channels light directly from outside into the interior space ( BCA, 2010). These types of natural daylighting mechanisms have clear benefits in tha t they reduce the need for electricity consuming artificial lights. Light ducts and light pipes can be incorporated into a new building design or an existing building renovation, while light shelves could be implemented on any type of building. Resident ial buildings in the design phase are able to be customized to operate using less energy, which was discussed in this section. They can be oriented to capture sunlight when it is needed, catch prevailing breezes and equipped with means to
88 improve natural daylighting. More efficient building materials can be used to help improve the energy efficiency of the building, and the interior can be equipped with high efficiency appliances, all to improve operating efficiency and reduce operating costs. These meas ures can all save occupants money over the life of the building, and many different federal, state and local incentives programs exist to provide opportunities for more residential building owners to take advantage of energy efficiency in their home, as di scussed briefly in the previous section. Existing Commercial Buildings Commercial buildings account for around 20% of energy consumption in the United States according to the US Buildings Energy Data Book ( US DOE, 2012 ). In 2010, these buildings used an estimated 19 quadrillion BTU (Nock, 2010). Energy Star estimates that around 30% of this energy is wasted, and that around 10% can be saved with minimal to no additional costs (Energy Star, n.d). The following sections will discuss information pertinent to retrofitting existing commercial buildings, but will refer to previous sections of this chapter as necessary. Building Shell Optimizing the efficiency of the existing commerc ial building shell is an integral component for improving the overall efficiency of the building for the same reason that the building shells of residential buildings need to be efficient. Heating and cooling requirements will be lower if less conditioned air is able to leak out of the buildingâ€™s envelope and behavioral use stays the same and does not increase. Heating and cooling comprises around 3 7% of commercial building energy us e, and improvements to the building shell will reduce this substantial requirement (Vandepool n.d).
89 Roof ing. Commercial buildings typically have flat ter, low sloped roofs that have the potential to be retrofitted to decrease energy usage. Incorporating green roof s pace can reduce heating and cooling loads, as can retrofitting the roof with a light colored h ighly reflective product. See the previous roofing section for an in depth discussion of the different types of roofs that can be installed to decrease heating and cooling loads. Cavity space between the exterior and interior of the roof should also be ai r sealed and insulated as possible to reduce energy transfer via conduction and infiltration. Flat roofs on commercial buildings have the additional capability of supporting solar photovoltaic and solar thermal arrays, which can provide electricity and hot water to the building and reduce reliance on fossil fuel generated electricity, although these strategies are out of the scope of this project . Exterior Walls. See the previous exterior wall section for a discussion of the different ways exterior walls can be treated to improve building efficiency. Windows/Doors . Windows and doors can be weatherstripped as discussed in the first section of this chapter to reduce air leakage and infiltration. Occupant behavior can be adjusted to utilize windows to prevent solar heat gain in warmer months and introduce it in colder months, like by using blinds and shades appropriately depending on the season. Solar screens, awnings and vegetation can also be used to help shade windows and doors and reduce energy gain, which can help to reduce HVAC requirements. These smaller improvements may help with energy savings and comfort in the building, but window replacements ar e also an option as discussed previously . The type of windows that should be installed in commercial buildings depends, like residential buildings, upon the energy consumption patterns that the building typically
90 experiences. Buildings with substantial cooling loads, for instance, would benefit from having low solar heat gain coefficient (SHGC) windows installed (Randolph, 2008). Efficient windows provide not only an opportunity for energy savings, but also comfort and occupant well being . If it is also possible to install operable windows in the building, ventilation and cross breezes can be captured, which can improve comfort in the building on mild days. Heating, Ventilation and Air Conditioning Heating and cooling accounts for a combined 3 7% of ener gy used in commercial buildings (US DOE, 2012) , and can be improved in a variety of ways. One of the most cost effective ways to manage energy use associated with HVAC equipment is to alter o ccupant behavior . T hermostat temperatures can be set slightly h igher in the summer and lower in the winter months , even more so when the building is not in use. Environmental management systems can also be installed to monitor the energy use of the buildings and adjust temperature settings accordingly (Benson, n.d). HVAC requirements can be reduced by improving the performance of the building shell, as discussed previously , however it is usually recommended that occupant related behavior be managed first to take advantage of less costly means of achieving energy savi ngs . The HVAC equipment can also be tuned up for ef ficiency and the duct system inspected and sealed and insulated if necessary , as d iscussed previously . HVAC filters should also be changed routinely as part of this maintenance, and inspections can be performed to make sure that vents are unblocked to allow for conditioned air to enter the building. Utilizing natural ventilation, if possible, can reduce HVAC requirements on milder days as well. These kinds of operations and maintenance practices can be
91 undertaken routinely to ensure that these systems are operating correctly and efficiently and to reduce energy consumption. After improvements to the operations and maintenance procedures in the building as well as to the building envelope, energy requirements from the HVAC system(s) will likely be reduced, and the building owner can decide whether or not to replace them based on the age and performance of the system(s), and the cost benefits from doing so. HVAC replacement options can be found earlier in t his chapter, but additional systems can be feasible to install in commercial buildings, such as heat recovery systems, economizers/heat exchangers to preheat water, and chillers with heat recovery capabilities (Wulfinghoff, 2004). Appliances Water heating accounts for around 7% of commercial building energy use, and other appliances comprise around 15% (Vandepool, n.d). A discussion of techniques and technologies that can reduce water heating requirem ents can be found earlier in this chapter , such as ins ulating water tanks and pipes, and setting the water heater temperature to 120 degrees Fahrenheit. Also pertinent to commercial buildings is the installation of low flow faucet and flush fixtures, automatic controls on fixtures, and encouraging building u sers to remain cognizant of their water consumption, which can help to reduce the amount of hot water that is needed and reduce the energy associated with pumping water into and out of the building. Repairing water leaks will also reduce energy consumptio n associated with pumping water in and out of the building. Similarly to residential buildings, high efficiency appliances can be installed to replace their standard efficiency counterp arts, as discussed earlier .
92 Where office equipment is concerned, u ser behavior can also be altered by implementi ng consumer awareness education and training building occupants on energy management and energy saving practices . Building users can be incentivized to turn off computers and other electronic appliances when t hey arenâ€™t needed, or power management systems can be activated on office computers to put monitors to sleep when they are not being used. Energy Star appliances like laptops and printers with lower energy requirements can also be purchased when older appliances are being phased out, and can help to cut down on energy consumption associated with these appliances. Lighting Lighting can account for as much as 26% of commercial energy usage and presents one of the biggest opportunities for e nergy reduction (Vandepool, n.d). A discussion of lighting techniques and technologies can be found in the earlier lighting section , but it is worth mentioning again the benefits of implementing light timers and motion sensors throughout the building to ensure that light s are only operating when they are needed. Building users should also be encouraged to turn off lights when they are not needed, which can reduce lighting expenses from 1040% depending on usage (Energy Star, n.d.). The use of natural daylight should also be en couraged when feasible and when i t will not substantially increase cooling needs in warmer months, and task lighting can be implemented to reduce the need for additional overhead lighting. Overall, commercial buildings benefit firstly from managing operations and management procedures from a more energy conscious perspective. Energy consumption can be reduced by employing â€œlow hanging fruitâ€ options discussed in this
93 section, and if it is properly tracked building owners can decide which steps to take to further reduce the buildingâ€™s energy consumption. Operations and maintenance improvements throughout the whole building can be followed by upgrades to lighting, plug load sources, and the building envelope, which can synergistically work to reduce the HVAC requirements of the building and potentially allow for a smaller capacity system to be installed (Energy Star, n.d.). Energy management systems can track where energy is being consumed in the building and provide insight as to where and how consumption can be reduced (ACEEE, n.d.). Retrocommissioning is a practice that can also be undertaken at the start of the efficiency improvement process to determine operational and maintenance improv ements that can be made in the building, and to develop a plan to implement these improvements and monitor them over time (ACEEE, n.d.). New Construction Commercial Buildings Commercial buildings can also be designed and constructed to use less energy, e mploying the same basic principles as discussed for new construction resident ial buildings . As with new construction residential buildings, the projected energy usage of commercial buildings can be modeled in the design phase using a variety of building m odeling and simulation software, which can help determine the best methods for energy reduction ( ACEEE, n.d.). New commercial buildings can also undergo commissioning processes, which begins at predesign phases and continues through early operation of the building (ACEEE, n.d.). The purpose of commissioning is to make sure the building systems and operating equipment are installed and tested to perform
94 the way the building owner desires (ACEEE, n.d.), and in this case essentially provides a means to assure that building efficiency goals will be met. Appropriate siting and orienting of the building to employ passive solar can, if properly implemented, inherently reduce heating and cooling loads, whic h is the largest use of energy in commercial buildings. Passive solar techniques also assist in daylighting, which, when coupled with natural lighting technologies discusse d earlier, cuts down on energy use associated with lighting, the second l argest energy user in commercial buildings. The remainder of the energy efficiency measures, techniques and technologies that can be applied to new designed commercial buildings have been discussed in this chapter already. Refer to the previous three secti ons of this chapter for more indepth discussions of the different measures, techniques and technologies that can be implemented into new construction commercial buildings. Newly designed/constructed commercial buildings have the benefit of easier implementation of energy efficiency st rategies as compared to existing commercial buildings. It can be more cost effective to incorporate many of the efficiency measures into the building during construction, and the hope is that more new construction buildings will implement these strategies and help drive the cost of energy efficiency measures down. Conclusion The means of achieving energy efficiency in new construction and existing residential and commercial buildings are largely the same, however some methods and technologies are more appropriate in some situations over others. For instance, it is much more cost feasible to insulate exterior walls of a new construction building than an
95 existing building, which can vastly improve the energy efficiency of the building. New construction buildings also have the added benefit of having efficiency built into the design, as evidenced particularly by the fact that they can be oriented to operate passively, and if carried out correctly can achieve very high levels of energy efficiency. Despite the foundational differences between new construction and existing buildings, many of the same specific efficiency technologies can be employed in all four building types. This chapter highlight s the major types of efficiency measures, techniques and technologies and illustrates where various options can be implemented. It should be reiterated, however, that the appropriateness of these energy efficiency measures varies from building to building, based on its age, geographic location and climate, l ayout, occupant behavior and many other factors. Certain energy efficiency measures will not be as effective in some buildings as compared to others, which is why it is generally a good idea to have a building inspection or audit performed. This would in clude running a building energy model, which can give a reasonable estimation of the predicted energy and monetary savings associated with individual and combined energy efficiency measures. The next chapter of this report does just that, and reports the findings of energy efficiency models run on four different theoretical buildings, one existing residential, one new construction residential, one existing commercial and one new construction commercial.
96 CHAPTER 5 ENERGY MODELING FINDINGS AND DISCUSSIO N Existing Residential Building A s discussed in the Methodology c hapter of this report, the 2,500 square foot, onestory detached low efficiency 1965 existing residential building m odeled in REM/ Rate was subjected to an energy analysis to determine the amount of energy used and theoretical money spent per year to operate the building. It was determined by the modeling software that under the modeled conditions, the building could be projected to consume 304.5 million BTU or 89,240 kWh equivalent per year through heating, cooling, water heating, lighting and appliances, or $4,743 per year spent on all energy costs. Space heating was found to comprise the majority of this usage and expenditure, followed by cooling, lights and appliances, and water heating. A screen shot of the as is energy analysis can be seen below: Figure 5.1 Analysis of the annual energy consumption of the existing residential building
97 It can be seen from this image that space heating was modeled as consuming nearly 88% of the total energy usage, and around 73% of total energy costs. This can be at least partially attributed to the inefficient state of the building shell and the building in general and less window space on the south facing walls than on the east and west facing walls , coupled with a moderately high thermostat setting in the winter months. These inefficient parameters were intentionally imposed on the building to figure out the most effective ways of improving its efficiency. However, the high proportion of energy us age and cost consumed by space heating could also have been influenced by program or user error, as it was not apparent in the energy modeling program that accurate weather data was utilized in the model, which could have b een a contributing factor to arti ficially inflated usage numbers. As mentioned in the Research Methodology chapter, four different â€œpackages,â€ each of which contained different combinations of efficiency upgrades, were run on the existing residential building. The first package included all of the possible and applicable upgrades, such as exterior wall, slab and attic insulation; window and door replacements; duct insulation and sealing; whole house air sealing; heating, cooling and water heater replacements; high efficiency lightbulb i nstallation; refrigerator, dishwasher, ceiling fan, clothes washer and dryer replacements; and plug load reductions. The second analysis, called the â€œbase packageâ€ analysis, included slab, attic and duct insulation; door replacements; whole house air seali ng; high efficiency bulb installations; ceiling fan installations; and plug load reductions. The third â€œshellâ€ package included slab, exterior wall, and attic insulation; window and door replacements, and whole house air sealing. The fourth â€œapplianceonlyâ€ package
98 included only replacing heating, cooling, water heating, and major appliances; as well as duct insulation and sealing; and highefficiency bulb installations. These analyses were run using pricing obtained from a home efficiency contractor in the DC area, and various home improvement stores like Loweâ€™s and Hom e Depot , as seen in the table below. Table 5.1 Table of efficiency improvements and estimated costs Upgrade Cost Source R 7 to slab $1.30 per linear foot Ecobeco LLC R 19 to floor $1.50 per square foot Ecobeco LLC R 22 to exterior wall $3.60 per square foot Ecobeco LLC Double pane, low e argon filled windows $200 each Loweâ€™s Polyurethane core exterior door $400 each Loweâ€™s R 30 to attic $1.60 per square foot Ecobeco LLC 94 AFUE gas f urnace $5,000 Home Depot 14 SEER AC unit $3,000 Home Depot Tankless water heater $1,300 Home Depot Programmable thermostat $100 Home Depot Duct insulation $300 Ecobeco LLC Duct sealing $1,850 Ecobeco LLC Air sealing $1.10 per square foot Ecobeco LLC High efficiency lighting $10/bulb Home Depot High efficiency refrigerator $1,200 Loweâ€™s
99 High efficiency dishwasher $1,000 Loweâ€™s High efficiency ceiling fan $200 Home Depot High efficiency clothes washer and dryer $2,000 Loweâ€™s The â€œtotal packageâ€ was estimated to cost $35,849 with $3,267 total savings per year, and an overall payback period of around 11 years. The annual expenditures for operating the home dropped from $4,741 to $1,475. The annual savings to investment ratios r anked, from high to low, highefficiency lighting, plug load reductions, slab insulation, east and west window replacements, exterior wall insulation, north and southfacing windows, attic insulation and whole house air sealing, door replacements, water heater, cooling, heating, refrigerator ceiling fan, dishwasher and clothes washer/dryer replacements. The duct sealing and insulation measures did not appear to have significant savings to investment ratios in this scenario either. The highest annual savi ngs came from exterior wall insulation, while the lowest came from duct insulation, and Fig ure 5.2 on the following page shows the overall ranking of the efficiency upgrades by annual dollar savings , which are listed at the top of each bar. The â€œbase packageâ€ (slab and attic insulation, door replacements, duct insulation, whole house air sealing, highefficiency bulb installation, plug load reductions, ceiling fans) attains annual savings of $833 and would cost an estimated $9,626, for an overall simple pay back period of 12 years.
100 Figure 5. 2 Annual Savings for Retrofits under the â€œTotalâ€ Package With this package option, $3,908 would still be spent on energy costs per year, down from $4,743. The highest savings to investment ratio is again achieved by highefficiency lighting, followed by plug load reductions, slab insulation, attic insulation, w hole house air sealing, door replacements, ceiling fan replacements, and duct insulation. The highest annual savings are achieved by slab insulation, followed by attic insulation and whole house air sealing. The bar chart below shows the annual savings f or the base package retrofits, with the projected annual savings amount above each measure. Figure 5. 3 Annual Savings for Retrofits under the â€œBaseâ€ Package
101 The â€œshellâ€ package (slab, exterior wall, attic insulation; window and door replacement, whole h ouse air sealing) was estimated to cost $19,289 and save $2,678 per year, with an overall payback period of just over 7 years. The annual expenditures for the home dropped from $4,741 to $2,063 per year. From high to low, the savings to investment ratios ranked: slab insulation, east and west window replacements, exterior wall insulation, north and southfacing window replacements, attic insulation, whole house air sealing, and door replacements. The highest annual savings came from exterior wall insulati on, and the lowest came from door replacements. The overall ranking of the efficiency measures are again shown in the bar chart below. Figure 5. 4 Annual Savings for Retrofits under the â€œShellâ€ Package Lastly, the appliance package (heating, cooling, water heater, refrigerator, dishwasher, dryer/washer and ceiling fan replacements; duct insulation and sealing; high efficiency bulb installations; and plug load reductions) was estimated to cost $16,560 and save an annual $1,653, for an estimate payback period of 10 years. The annual energy expenditures dropped from $4,741 to $3,088 in this scenario. The savings to investment ratios ranked, highest to lowest, highefficiency bulbs, plug load reduction, duct leakage, duct insulation, heating, cooling, wat er heater, refrigerator, ceiling fan, dishwasher, clothes dryer and clothes washer replacements. The highest
102 annual savings come from duct insulation, and the lowest comes from the clothes washer. Once again, the bar chart on the following page shows the overall rankings of the efficiency measures. Figure 5. 5 Annual Savings for Retrofits under the â€œApplianceâ€ Package A summary table on the following page compiles the findings from these four package scenarios, and the full results and printouts from the REM/ Rate can be found in Appendix I. Many findings can be deduced from this table. The most expensive packages (total and shell), in this particular scenario, correspond with the highest annual savings, and the lesser expensive packages correspond with slightly lower annual savings. The payback periods for the total, base and appliance packages are comparable, while the payback period for the shell only package is around 3 years shorter. The base package has the highest payback period with the lowest upfront cost due to the comparatively low annual energy savings realized under this package. It is interesting to note that the two most expensive packages (total and shell) have the highest savings, which seems to be largely attributed to the addition of exterior wall insulation which, incidentally, is not included in the base or appliance packages.
103 Table 5. 2 : Summary of Findings for the Four Efficienc y Retrofit Packages Package Name Installed Measures Total Package Cost Annual Package Savings Payback Period Highest Saving Retrofit Total/Full Slab, exterior wall, attic insulation; window and door replacements; heating, cooling water heater replacements; duct insulation and sealing; wholehouse air sealing; highefficiency bulb installation; refrigerator, dishwasher, ceiling fan, washer/dryer re placements; plug load reduction $35,849 $3,267 10.97 years Exterior wall insulation ($992/year) Base Slab, attic, duc t insulation; door replacement , whole house air sealing, highefficiency bulb installation, plug load reduction, ceiling fan installation $9,626 $833 11.5 years Slab insulation ($269/year) Shell Slab, exterior wall, attic insulation; wholehouse air sealing; window and door replacements $19,289 $2,678 7.2 years Exterior wall insulation ($995/year) Appliance Heating, cooling, water heater replacements; duct insulation and sealing; highefficiency bulb installation; refrigerator, dishwasher, ceiling fan, washer/dryer replacements; plug load reduction $16,560 $1,653 10 years Duct insulation ($590/year) These results could help inform homeowners interested in energy retrofits as to which items to select depending on their budget. It is not surprising to find that the total package has the highest annual savings realization because it implements all possible efficiency retrofit options , although it only surpasses the shell package annual savings by $589 but exceeds it in cost by over
104 $16,000. The shell package is only $2,729 more expensive than the applianceonly package, but has over $1,000 more in annual savings. Thi s implies and supports the common belief that improvements to the efficiency of the building shell are more cost beneficial than upgrades to appliances only , and that implementing all possible efficiency retrofit measures will not necessarily be the best m onetary investment . As can be seen, t he base package is by far the least expensive, and serves to demonstrate potential savings that can be realized by implementing the â€œeasiestâ€ efficiency retrofit options. The more expensive options such as exterior w all insulation, window replacements, HVAC replacements, duct sealing, and major appliance replacements were left out of this pack age, reducing its price but along with that the potential for higher annual savings. However, despite its lower savings and hig her payback period, this option would still, as mentioned in the data presentation section above, bring the total annual energy expenditures to under $4,000 and could be a viable option for homeowners looking to improve home energy efficiency, reduce expen ditures on energy, improve comfort, but with a lower upfront cost. The table on the following page shows the cost, annual savings and savings to inve stment ratio (SIR) by measure. The retrofit options that consistently performed the best in terms of annual savings in all four package scenarios were east and west facing window replacements, slab insulation, exterior wall insulation, attic insulation, wholehouse air sealing and heating replacement, where applicable. This is reflected in the table below by the respective SIRâ€™s of these measures. Duct insulation and highefficiency bulb installation also had high overall savings to investment ratios; these
105 improvements that have an impact on HVAC performance and electric baseload, respectively. Table 5.3 Energy Efficiency Retrofit Characteristics by Measure Measure Cost ($) Annual Savings ($) SIR Slab Insulation 666 269 6.2 Exterior Wall Insulation 6,273 992 2.4 Attic Insulation 4,000 240 0.9 Window Replacement 4,400 948 4.3 Door Replacement 1,200 56 0.9 Heating Replacement 5,000 155 0.4 Cooling Replacement 3,000 124 0.6 Water Heater Replacement 1,300 68 0.7 Duct Insulation 300 590 25.9 Duct Sealing 1,850 116 0.94 Air Sealing 2,750 178 0.9 High Efficiency Bulb Installation 10/bulb 14/bulb 19.1 Refrigerator Replacement 1,200 26 0.3 Dishwasher Replacement 800 5 0.1 Ceiling Fan Installation 600 9 0.2 Washer/Dryer Replacement 1,200 5 0.06 The major appliance replacements did not achieve as high of annual savings, contributing to overall costs without necessarily reducing energy consumption and cost by a significant amount.
106 New Construction/New Design Residential Building The 2,500 square foot new design/new construction residential building was modeled in REM/ Rate to have much higher energy efficiency than the initial existing building for retrofit. The combination of insulated slab, the use of Structural Insulated Panels (SIPs) for exterior walls, high efficiency windows oriented to take advantage of passive solar opportunities, high effici ency doors, a well insulated attic, high efficiency HVAC equipment and duct system, a relatively tight shell, high efficiency appliances, and thermal massing was initially modeled as the designed state of the building, as can be seen in Appendix II. With these efficiency measures, techniques and technologies implemented, the total consumption of the building was projected to be 58.9 million BTU or 17,261 kWh per year, with a total annual energy cost of $1,421. Space heating was found to comprise 39% of the annual energy consumption and 21.5% of the cost, while lights and appliances were found to consume the secondhighest amounts of energy (35.6%) and around half of the annual energy costs. The enduse categories for energy consumption and energy costs can be seen in the charts below. Figure 5.6 End use categories for new residential energy consumption and costs New Residential Energy Usage by Application Space Heating Space Cooling Water Heating Lights and Appliances New Residential Energy Costs by Application Space Heating Space Cooling Water Heating Lights and Appliances Fees
107 The high percentage of end use energy by lighting and appliances compared to the rest of the categories has a few interpretations. At first glance the energy usage by lighting and appliance seems to be too high, but not necessarily when the rest of the conditions of the building are t aken into consideration. When the annual consumption for this enduse category is converted to kWh and spread out through the entire year, an average of 513 kWh is used per month on lighting and appliances, which is not incredibly high, especiall y considering that the lighting and appliance usage was not controlled for and estimated electric usage was also utilized . H igh efficiency measures will still consume a somewhat significant amount of energy if they are in frequent us e, a parameter which is set by the model . This is in almost direct opposition to the reason why space heating usage is comparable to lighting and appliances, and cooling is substantially lower â€”the shell of the building was designed to be efficient, which takes away from user responsibi lity in reducing energy consumption. Unless the building user chooses to heat and cool the building beyond what is necessary, they will inherently save on energy consumption due to the fact that the shell is efficient and less mechanical heating and cooli ng is needed. However, the annual energy expenditure on lights and appliances does seem artificially high, comprising just over 50% of the building costs at $743 per year. It seems, as just mentioned, that the proportion could be seen as an accurate refl ection of energy consumption due to the low requirements by the other systems in the house, but this overall baseload cos t stands out as being quite high. Once again, this could be attributed to not hav ing controlled for user behavior, because default usag e numbers are used by REM/ Rate , or it could be due to errors in the model that have not been
108 corrected for up until this point. Overall, the low energy consumption and annual costs stands in stark contrast to the numbers generated for the existing residential building, which consumed around 5 times as much energy as this new construction residential building. It can be inferred, as was expected, that a building with more, higher efficiency characteristics will perform better than one with few existing eff iciency characteristics. As was also mentioned in Chapter 3 of this report, a few different variations were run on this base model to determine any differences in energy consumption when certain parameters were changed. The first set of variations that were performed had to do with the orientation of the building and placement of the windows. When the numbers of windows were kept the same but rotated (in two separate scenarios) to the east and west, the overall energy consumption and costs increased sli ghtly, but not by significant amounts. The increases were found in the heating and cooling loads, but only caused a cost increase of $12/year, as can be seen below. Base Model Result s: Window Orientation Results Figure 5.7 Base model and window orientation results, new residential
109 The results from this data change can be expected; it is believed that slight variations off truefacing directions will not have a sizeable impact on the ability of a building to operate pass ively, which in turn would not have a dramatic impact on building energy consumption and costs. The next set of variations that were made dealt with the number of southfacing windows, with all other windows remaining constant. The number of southfacing windows was first reduced to 4 from 12 in the original model, which caused an overall drop in the annual heating consumption and estimated a $20 per year decrease in overall energy costs. The energy consumption and costs climbed as more windows were added , from $1,401 per year with 4 southfacing windows (10% of the wall area) to $1,474 per year with 24 southfacing windows (61% of the wall area). These rises in energy costs are all attributed to higher heating consumption, which seems somewhat contradict ory to the principles of heating a building using passive solar. It would stand to reason that the more windows facing south, the less the heating requirements would be; however these results disagree with this principle and point to the realities of pass ive design, which recognizes that while windows provide solar heat gain during daytime hours, their lower R value comparative to walls allows for higher levels of heat loss at night. In this case, as passive design practitioners caution, there is a balanc e between too many and too few southfacing windows, and in this case the heat loss through too many windows at night could not be offset by the thermal mass that was modeled as existing in the building. This would tend to agree with the results that were obtained when the fewest southfacing windows were modeled; there is less heat loss when there is less glazing on the southfacing wall. However, heat gains through the
110 southfacing windows can in theory offset additional heating requirement s depending o n location , in which case perhaps the geographic location chosen in this scenario was not optimal for these combinations of passive solar design principles. It seems unlikely that having only 10% of the southfacing wall covered with glazing would provide sufficient free, solar heat to reduce mechanical heating needs to the extent implied by the energy analysi s. However, as was just mentioned, a balance between window and wall area and R values, as well as internal heat gains, need to be considered for optimal passive operation. Future improvements to this set of modeling will be discussed in Chapter 6 of this report. The last variations that were made to this model pertained to HVAC equipment. REM/ Rate has the option to model geothermal heat pumps, w hich was the first HVAC variation to be made to the model. Keeping all other parameters the same as the original model, a 4 ton, 3.1 coefficient of performance (COP) 14.2 energy efficiency rating (EER) appliance was run as being the only heating and cooli ng system. The heating load dropped down to 1,612 kWh per year, and the cooling load dropped to just 322 kWh per year, with total energy operating costs of $1,292 per year. The reduction in heating and cooling loads and costs is not surprising, as geothermal heat pumps can be a highly efficient means of meeting heating and cooling needs. This option was chosen to demonstrate the additional savings potential from implementing an even higher efficiency HVAC system, with the added practicality of implementation since the building site would have needed to undergo construction anyway. The use of geothermal was not included in the base model because of the higher overall purchase,
111 install and maintenance costs, which may not be attractive or feasible to the average homeowner. The second HVAC variation that was made was modeling an integrated space/water heating system, which serves to operate space heating and water heating simultaneously. Heating, cooling and water heater energy consumption and costs all d ecreased when this appliance was modeled, bringing the total energy costs to $1,352 per year. This is less than the energy costs found from the base and window variation models, but more than the geothermal predicted energy costs. The substitution of even higher HVAC systems than the 94 AFUE furnace and 14 SEER AC unit initially modeled shows, overall, a greater reduction in annual energy costs, but not by such a substantial amount that necessarily offsets the higher capital costs of these traditionally m ore expensive HVAC systems. The tables below and on the following page show a summary of the findings from the different building models run: Table 5.4 New residential consumption findings summary table Model Annual Consumption (kWh equivalent) Heating (kWh equivalent) Cooling (kWh) Water Heating (kWh equivalent) Lights/ Appliances (kWh) Total (kWh equivalent) Base 6,770 674 3,663 6,154 17,261 Window Orientation 6,975 703 3,663 6,154 17,495 South Facing Windows 4 windows 6,360 674 3,663 6,154 16,851 8 windows 6,535 674 3,663 6,154 17,026 16 windows 7,092 703 3,663 6,154 17,612 20 windows 7,473 703 3,663 6,154 17,993 24 windows 7,913 703 3,663 6,154 18,433 HVAC Systems Geothermal 1,612 322 3,663 6,154 11,751 Integrated Space/Water Heating 6,037 615 3,458 6,154 16,264
112 Table 5.4 indicates that the lowest energy consumption is estimated when the geothermal heat pump system is modeled along with the highly efficient shell, thermal mass and 30% of the directly southern facing wall covered with glazing. The highest energy consumption is estimated when a highefficiency HVAC system comprised of a furnace and AC system is modeled with the same base parameters and 61% of the southfacing wall is modeled as being covered with glazing. The modeling of higher efficiency HVAC systems broug ht down the total energy consumption, while the addition of more southfacing windows caused an increase in energy consumption. Table 5.5 New residential cost findings summary table Model Annual Costs ($) Heating Cooling Water Heating Lights/ Appliances Fee Total Base $306 $96 $156 $743 $120 $1,421 Window Orientation $315 $99 $156 $743 $120 $1,433 South Facing Windows 4 windows $287 $95 $156 $743 $120 $1,401 8 windows $295 $95 $156 $743 $120 $1,409 16 windows $320 $96 $156 $743 $120 $1,435 20 windows $337 $97 $156 $743 $120 $1,453 24 windows $357 $97 $156 $743 $120 $1,473 HVAC Systems Geothermal $227 $46 $156 $743 $120 $1,292 Integrated Space/Water Heating $257 $85 $147 $743 $120 $1,352 It can similarly be seen from Table 5.5 that the lowest energy costs are attributed to the package wherein a geothermal heat pump was run as existing, and the highest consumption and costs were achieved when there were 24 southfacing windows taking up 61% of the southfacing wall. The se results show that there is a balance that can be struck when it comes to adding southfacing windows to a building and that too many southfacing windows would cause an increase in heating loads. It is interesting to
113 note, however, that the lighting costs stay consistent throughout all the models, despite the fact that more or fewer windows would mean a difference in daylighting, which would seemingly cause variations in lighting consumption. It is worth noting that this energy modeling program may not take into consideration these types of relationships but that in real life operation, lighting schedules can be set by occupants and lighting systems can also be installed that dim in response to admitted daylight . I t is also worth noting that overall, there are small differences in energy consumption, and therefore costs, between the highly efficient base building and the variations performed on it, shown in the tables above. This indicates that in this case the marginal gains in efficiency from addition al variations compared to the base building may not necessarily be cost beneficial . The increase in efficiency and additional savings from geothermal, for instance, is 5,510 kWh and $129 per year, which is likely not high enough to justify the additional costs of this upgrade . Existing Commercial Building As was discussed in the Methodology chapter of this report, the eQUEST program was utilized to model various energy efficiency upgrades to an existing commercial building in order to determine energy sav ings. The existing building was modeled as being a 25,000 square foot twostory detached office building with low efficiency measures oriented along the northsouth axis. The upgrades t hat were modeled are as follows: R 60 fiberglass batts insulation + r adiant barrier to the roof R 21 polyisocyanurate insulation to the exterior walls R 10 insulation under slab
114 Quadruple pane low emissivity krypton filled window replacements Window shades added to all windows Daylighting modifications to the building with higher efficiency lightbulb installation Relaxation of thermostat settings to 78 degrees Fahrenheit cooling and 69 degrees Fahrenheit heating during the day, and 83 degrees Fahrenheit cooling and 63 degrees Fahrenheit heating during the night Installation of high efficiency HVAC systems; 14 EER cooling, 95 AFUE heating Relaxation of water heating temperature from 135 to 125 degrees Increase of water heater tank insulation to R 12 The results from modeling these upgrades were output in eQUEST, which was able to determine the annual energy consumption of the baseline building, as well as the energy consumption by each individual scenario that modeled an energy efficiency upgrade, as well as the â€œcascadedâ€ cumulative savings . The eQUEST software found that this building consumed 259,870 kWh and 495 MB TU per year originally. The estimated breakdown of electric and gas consumption by end use can be seen in the image on the following page. Around a quarter of the electricity consumption i n this theoretical building is used by lighting, and nearly 30% is used by cooling equipment. The only gas uses are for space and water heating.
115 Figure 5.8 Existing commercial energy enduse The energy modeling software used in this portion of the pr oject was able to model a number of energy efficiency improvements, as outlined above, individually and in a â€œcascadedâ€ cumulative fashion. Estimated annual electricity and gas consumption were generated for each energy efficiency improvement, and a summary table of these results can be found on the following page. It is noted that the lowest annual electrical consumption is associated with the scenario in which only high efficiency HVAC replacements are modeled, followed by the modeling of just the dayli ghting management strategies, then the window replacements only, window shading only, thermostat management only, roof insulation only, exterior wall insulation only, and water heater management only. One anomaly found is that adding floor insulation resul ted in predicted electricity consumption higher than the baseline building; it should be noted that a reduction in cooling loads can be achieved by heat loss to the ground through slabs and that the addition of insulation may not allow for this to occur, r esulting in higher AC needs.
116 Table 5.6 Existing commercial energy consumption Electric Consumption (thousand kWh per year) Gas Consumption (M BTU per year) Baseline 260 495 Roof Insulation 259 447 Exterior Wall Insulation 259 461 Floor Insulation 262 478 Window Replace 247 387 Window Shading 247 512 Daylighting 245 507 Thermostat Management 256 468 HVAC Replace 230 457 DHW Management 260 461 It is noted that the overall reductions in electricity consumption in these scenarios is somewhat minimal, with the greatest savings from highefficiency HVAC installations being 30,000 kWh per year compared to the baseline building. This deviates from the expected result, in which there would be greater electricity savings associated with the insulat ion measures as compared to the baseline, since a better insulated shell would require less in terms of cooling demands. However, the lower electrical consumption due to improvements in lighting, shading and window efficiency, and thermostat management wer e expected, although there is a seemingly small difference between the electrical consumption in the baseline scenario and these scenarios. The heightened electric savings associated with the new HVAC systems can be attributed to higher operating efficiency, which would inherently lower cooling consumption in the summer months.
117 Table 5.6 also shows the predicted annual gas usage of the building. The energy efficiency measure that generated the least amount of gas usage, or the highest gas savings, was the window replacement scenario, followed by roof insulation, HVAC replacements, water heater management, thermostat management, exterior wall insulation and floor insulation. The window shading and daylighting improvement scenarios predicted a higher gas usage than the baseline building. Higher gas savings associated with highefficiency window installations could be at least partly attributed to the fact that this particular building was oriented so that the longest sides face east and west, and an unsu bstantial amount of solar heat gain is captured by southfacing windows in the baseline windows. The heat loss associated with the baseline inefficient windows could have been large enough to generate significant gas heating savings when they were replaced with highefficiency alternatives, even though the ability of the building to be heated passively would not have changed. The contribution of roof insulation and HVAC efficiency to gas savings makes sense intuitively, as a higher R value will prevent energy transfer between the interior and exterior of the building, and high efficiency furnaces will more efficiently heat the interior spaces using less fuel, especially when the heating temperature is set to a more energy efficient setting. Exterior wall and floor insulation also showed to contribute to gas savings, though not as much as roof insulation. The management of water heating included turning the water heater temperature down and improving insulation on the tank; the resulting savings in gas usage are predictable based on this and serve to solidify the abilities of the modeling software to generate feasible scenarios , and that energy savings can be achieved via easily implementable solutions . The results of the scenario in which
118 window shading w as added can also likely be explained logically; shading the windows will decrease the amount of heat that is able to enter the room, thus increasing the need for space heating and gas usage. The higher gas usage associated with improved daylighting does not seem to fit in with expected results. It is possible that the substitution of incandescent lightbulbs with high efficiency bulbs would reduce internal heat loads and require additional mechanical heating, but this anomaly is not clear at this time. Ov erall, the gas savings were higher when compared to savings associated with electric consumption, as window replacements generated gas usage that was 22% less than the baseline building. This would imply that the energy efficiency components modeled in thi s scenario are more beneficial to saving gas than electricity, which may be particular to this exact building scenario. Based on examination of the electrical and gas savings a ssociated with each individual energy efficiency improvement in this particul ar modeling scenario, it would seem as though highefficiency HVAC installation has the greatest overall individual impact for energy savings, followed by highefficiency window replacements. The table on the following page ranks the individual efficiency improvements based on their electric and gas consumption. Building management techniques, such as thermostat management and water heater management, also rank relatively high, which indicates that building energy management systems could be a useful stra tegy to reduce overall electricity and gas consumption.
119 Table 5.7 Ranking of existing commercial improvements by savings Rank Rank by Electric Consumption Rank by Gas Consumption 1 HVAC Replace Window Replace 2 Daylighting Roof Insulation 3 Window Replace HVAC Replace 4 Window Shading DHW Management 5 Thermostat Management Exterior Wall Insulation 6 Roof Insulation Thermostat Management 7 Exterior Wall Insulation Floor Insulation 8 DHW Management Daylighting 9 Floor Insulation Window Shading Floor insulation ranks at or near the bottom for both types of energy savings, implying that in this particular scenario it should not necessarily be pursued in energy efficiency retr ofits . Despite their inconsistent savings performance according to this energy model, the addition of other shell insulation could still prove to be beneficial in overall commercial building savings, although further energy modeling that is more specific to each individual case would of course be recommended to better determi ne this. eQUEST also has the ability to â€œcascadeâ€ the individual improvements to determine cumulative annual energy and cost savings for a whole package of energy efficiency measures. This is useful if more than one efficiency improvement is desired, and can be run in multiple combinations, as will be discussed in the next chapter. Th e cumulative results from modeling all of the possible energy efficiency measures are shown in the table on the following page.
120 Table 5.8 Cumulative Electricity and Gas Sa vings Measure Electricity Savings (kWh) Gas Savings (therms) Roof Insulation 1,073 477 Wall Insulation 1,393 832 Slab Insulation 1,167 994 Window Replacement 11,179 2,082 Window Shading 19,804 2,027 Daylighting 34,757 1,959 Thermostat Management 38,029 2,068 HVAC Replacement 61,700 2,124 DHW Management 61,700 2,457 Total Savings 24% 50% This table indicates several important findings that relate to the findings that have already been discussed. The highest electricity savings are, once again, realized when HVAC replacements are modeled as being added, and increased electrical usage would be required if slab insulation was added. Because the water heaters in the building are powered by natural gas, there are no electricity savings associ ated with water heater management. The highest gas savings are associated with window replacements, while daylighting and shading would require slightly increased gas usage due to less passive heat gain (and a subsequent higher heating demand) due to shad ed windows, as described earlier. If all of these measures were implemented, a total of 61,700 kWh per year, or 24% , of electricity could be saved in the building, as well as 2,457 therms
121 per year, or 50% savings , on gas. Slab insulation could be removed due to its higher associated electricity usage, meaning a 25% savings on electricity and 46% savings on gas would be achieved. This exclusion may or may not be appropriate when the small increase in electricity savings versus the larger decrease in gas savings is considered . The inclusion or exclusion of slab insulation would depend on the building ownerâ€™s budget and further analysis of their individual building. The daylighting and shading measures could also be taken out due to their respective gas usage increases of 55 and 67 therms, respectively, but these measures contribute savings on electricity of 8,625 and 14,953 kWh, respectively, and w ould likely benefit from being left in. It can be seen from the evaluation of the cumulative data that a sub stantial amount of energy can be saved if all of the energy efficiency improvements are made to the existing commercial building. The appropriateness of undertaking the whole package of retrofits would depend on costs, budget and financial analysis, which was not performed in this study. Commercial buildings are often not fully retrofitted and instead implement only a few energy saving solutions. Because of this, it may be more beneficial for a commercial building owner to look at the savings associated with indiv idual measures, and plan their energy saving solutions based on that. New Construction/New Design Commercial Building As discussed in the Methodology chapter of this report, the new construction/new design commercial building scenarios were run in eQUEST to determine the electric and gas consumption of a 25,000 square foot, twostory office building that was modeled as being in a principally efficient state. All the highest efficiency options were selected, from building insulation to HVAC equipment, and the orientation of the building
122 was set to attempt to take advantage of passive solar heating. The occupant dependent parameters, such as thermostat setting and lighting usage were kept the same as the existing commercial building to more easily facilitate necessary comparisons between the two commercial buildings. It was estimated by eQUEST that the new construction commercial building with all high effi ciency elements would use 248,60 0 kWh and 252 MB TU per year. For comparison, the standardto low efficiency existing commercial building was predicted to use 260,000 kWh and 495 MBTU per year. These results show that the high efficiency building uses substantially less gas per year, but the differences in electrical consumption are comparatively minimal. It is also noted that the electric consumption by the new, high efficiency commercial building is predicted as being higher than an existing commercial building that is retrofitted to have high efficiency HVAC systems installed, as well as when daylighting was improved and when window replacements and window shading were modeled as being added to the building. This could be attributed to any number of factors, since many of the conditions of the existing and new construction buildings were different from each other. It is possible that there is an error in the modeling system, since the expected outcome would be that less electricity would be consumed by the new construction building with higher efficiency elements built into it from the start. It is also possible that the number of windows on the east and west walls without adequate amounts of shading would contribute to heat gain in the summe r, which would possibly indicate that the highefficiency windows selected for this model were not appropriate and are not suitable for this particular application. As can be seen from the image on the following page, which depicts the energy consumption in
123 this baseline high efficiency scenario by end use, the hig hest proportion of electrical consumption is attributed to â€œMiscellaneous Equipment,â€ followed by space cooling, ventilation fans and area lighting. The miscellaneous equipment category includes miscellaneous plug loads like office appliances and electronics that do not fit into the other categories, elevators and escalators, and some process equipment . According to the eQUEST manual, this category captures â€œall other items which contribute to heating and cooling loadsâ€ (DOE, 2009) and it does not seem li ke the energy consumed by this enduse category could be altered based on user inputs, which could partially explain why the electrical consumption does not seem to be much lower in this scenario than compared to the existing commercial building. Fig ure 5.9 New construction commercial energy enduse The substantially lower gas consumption can be attributed, according to the model and the image above, only to savings in space heating and water heating. This
124 is to be expected as the HVAC and water heat er efficiencies were modeled as being much higher than the existing building, and because of the high efficiency of the building shell. The orientation of the building and placement of the windows would also play a role in passive heating of the building, which would lower gas consumption for space heating. As was also mentioned in Chapter 3 of this report, the number of windows on each wall was varied to determine the impact on electric and gas consumption. In the first altered scenario, the percentage of the northern, eastern and western facing walls that are covered with windows was reduced from 53.3% to 33.3%; the southern wall glazings were held constant. When eQUESTâ€™s energy simulation was run after this change was made, it was found that 246,30 0 kWh and 22 3 MB TU per year would be consumed by the building. The same type of scenario was rerun again, wherein the percentage of the northern, eastern and western walls taken up by windows was reduced to 23.3%, and the southern wall was again held constant. This energy simulation predicted electricity consumption of 247,3 0 0 kWh and gas consumption of 211 MB TU . The findings from all of these simulations are shown in the following table. Table 5.9 Electric and gas consumption with window variations Electricity Consump tion (kWh/year) Gas Consumption (MB TU /year) Baseline High Efficiency Building 248,6 0 0 2 52 33.3% windows on N, E, W Walls 246,30 0 22 3 23.3% windows on N, E, W Walls 247,30 0 211
125 It can be seen that, once again, the differences in electricity consumption are negligible overall, although the consumption does in general decrease when fewer windows are modeled on the north, east and west walls of the building ; the increase in electricity consumption from 33% to 23% could be explained at least in part by additional lighting requirements , but there are likely other contributing factors as well that cannot be determined at this time. The overall downward trend seen in this table , however, fits in with what is typically expected, since fewer windows on the east and west walls, particularly, mean less heat gain in the summer that would need to be offset by increased cooling loads. As for the decreased gas usage associated with fewer windows on these three walls, it is possible to attribute at least part of this to reduced air infiltration around and through the windows in winter months; fewer windows on the building means less energy transfer and therefore less heat loss in the winter that would need to be compensated for by increased space heating. The end use consumption charts generated by eQUEST, similar to Figure 5.14, were also examined to determine the predicted allocation of electrical and gas consumption in the scenarios just discussed, where fewer windows were modeled as existing on the north, east and west facing walls. The table on the following page summarizes the enduse consumption charts for all three scenarios run. It is noted that the same percentage of electricity consumption is allocated to powering miscellaneous equipment in each scenario. This substantial allocation of electricity consumption could be responsible for the overall consistent electricity consumption between this building and the existing building, despite all the highefficiency components modeled in this scenario.
126 Table 5.10 New construction commercial energy end use by percentage Baseline High Efficiency Building 33.3% W indows on N, E, W Walls 23.3% W indows on N, E, W Walls Percent Electricity Consumption Misc Equipment 36% 36% 36% Cooling 25% 24% 23% Lighting 17% 19% 20% Ventilation Fans 20% 19% 19% Pumps/Aux 2% 2% 2% Percent Gas Consumption Space Heating 58% 52% 50% Water Heating 42% 48% 50% If the modeling program allocates over a third of the electricity consumption to one category that seemingly cannot be improved or altered, then overall electricity consumption can only be reduced so much by improvements t o the other end use categories. It could not be determined from the eQUEST user manual or the modeling software itself why such a large amount of electricity was allocated to this category. T he amount of electricity required for cooling decreases as the number of windows on the north, east, and west walls decreases, which can likely be attributed to lower solar heat gains. The amount of electr icity required for lighting increases as the number of windows decreases, which is expected as fewer glazings means less natural daylighting. Gas usage for space heating drops as the number of windows on these three walls decreases, which means a higher proportion of gas usage is instead allocated to water heating. It is possible that the reduction in space heating requirements as window numbers decrease can be attributed to less heat loss through these windows .
127 CHAPTER 6 CONCLUSIONS AND FUTURE IMPROVEMENTS TO RESEARCH Existing Residential Building It can be concluded from modeling energy retrofits to an existing residential building that improvements to the building shell seem to have the greatest impact in terms of saving energy and, therefore, money. This supports the theory that tightening the envelope of the building will keep conditioned air inside the building for longer periods of time while reducing unconditioned outside air infiltration. This reduces heating and cooling loads, and requires the installed HVAC system to work less. Installing more energy efficiency retrofits and upgrades will save more money, but will also cost more money which may not be a feasible option for many homeowners, especially if financial incentives are not available. The availability of different package options could help different homeowners assess the feasibility of pursuing various energy efficiency retrofit items. Future Improvements to Research These findings were largely to be expected, but there are still improvements that could have been made in the event that more time and resources were available to expend on this research project. The utilization of a more comprehensive and potentially acc urate energy model would have increased confidence in the findings, especially in regards to initial energy usage and monetary expenditures, which seem inflated. Investigating and experimenting with the energy modeling software, including comparing differ ent programs to determine differences between them, would increase confidence in the conclusions and recommendations.
128 Several more improvements could also be made. F irst , the average ages for single family homes in the DC area as well as ages of HVAC and appliances, the average insulation levels and other building characteristics could be used to define the existing residential building model . In addition, different levels of existing building efficiency could be modeled, from low to high efficiency , with iterations in between based on varying building parameters. These could include different building orientations, product efficiencies, window placements, insulation levels, etc. It would also improve the credibility of the results to gather more co st data for the energy efficiency upgrades and use average numbers to ensure that the costs and financial metrics are not too high or too low. The geographic regions could be expand ed from Washington, D.C. to different areas of the country. While the lim ited geographic location serves an example of the savings that can be realized by improving a buildingâ€™s energy efficiency, it does not apply to many areas of the country, and therefore does not apply to all potentially interested homeowners. New Constru ction/New Design Residential Building It can be concluded from this modeling scenario that a new construction residential building with highefficiency components will have substantially lower energy consumption and associated costs than a low efficiency, existing residential building. A higher efficiency building shell seems to make a sizeable contribution to the overall energy consumption, reducing heating and cooling loads throughout the year. The energy usage and cost proportion of smaller enduse cat egories, like lighting and appliances, therefore increases as traditionally higher consuming building components require less energy.
129 The higher the percentage of southfacing glazing, the higher the energy use. H owever , lighting loads did not vary even when more southfacing windows were added. The higher estimated heating costs could be attributed to insufficient thermal mass as more glazing was added to the southfacing wall; higher heating gains throughout the day will be lost during the night if they are unable to be sufficiently stored in thermal mass and then be released at nighttime. The model estimated the lowest energy consumption and costs when geothermal and integrated space/water heating HVAC systems were individually modeled. Since space heating is still a sizeable amount of the overall energy consumption of the building even with an efficient building shell, this finding makes sense as highly efficient HVAC systems like geothermal require less energy input than traditional furnaces, even if these are also highefficiency. An optimal level of glazing to take advantage of passive solar, coupled with a highly efficient building shell and HVAC system could have a marked impact on the overall energy consumption of the building, however the ove rall savings associated with the different variations were not large enough to necessarily justify additional expenditures for geothermal or window reconfigurations . Future Improvements to Research In future iterations of this portion of the project, more experimentation would be performed to determine the optimal numbers of windows in the building to best take advantage of passive solar opportunities in this particular geographic location. There ar e many more scenarios that could be run in which different parameters are changed along with the window placements and numbers, which could impact the overall energy consumption of the building and reduce energy costs. Experimenting with different
130 geographic locations could also be beneficial to determining the capabilities of this particular building of supporting passive solar principles, and could rule out the Washington, D.C. area as a good location for this building with its particular characteristics; or at the very least help to determine the most appropriate passive solar characteristics for the area. Additional variations would also include increasing the thermal mass as more southfacing glazing is added so that these components are able to work in conjunction to provide sufficient heat throughout the day and night in the winter time. Optimizing the balance of these various components could prove to be what is needed in order to model the lowest energy consumption and costs possible for this part icular building. In future versions of this project, cost data should be compiled to attempt to determine the costs of the efficiency features in the new residential building, which has an effect on whether or not they could be feasibly implemented. The purpose of running these particular scenarios, however, was to determine how efficient a residential building could be modeled to be, under the constraints of the REM/ Rate software. There exists research determining the additional costs of adding highe fficiency components to newly designed/constructed buildings, but this was not the aim of this portion of the research project. Existing Commercial Building The commercial building energy modeling determined that there were certain energy efficiency impr ovements that can be made to reduce electric and gas consumption, and others that seem to have a negligible or counterintuitive effect. Replacement of less efficient HVAC equipment with highefficiency alternatives saves
131 the most in terms of electricity i n this scenario, and saves the secondhighest amount of gas as well. It can be concluded that this is the single most influential measure that can be implemented in this theoretical existing commercial building to reduce overall energy consumption. Window replacements had a notable impact on overall energy reduction as well, and could also be considered a viable option for energy reduction in this building. Other measures, such as adding roof, wall and floor insulation, seem to have greater impacts on gas consumption reduction, and minimal reductions in electric consumption compared to the baseline building (except for floor insulation, which had a higher electricity consumption associated with it). Smaller improvements, such as adding window shading, im proving daylighting, and thermostat and water heater management had energy reductions associated with them as well, but it would be interesting to be able to see if their combined impact would prove greater or similar in magnitude. Energy management systems that are able to track and modify a buildingâ€™s energy settings could prove to be a valuable addition, in conjunction with high efficiency HVAC and, in this case, highefficiency windows. Future Improvements to Research As with the previous energy modeling scenarios, the existing commercial building could have benefitted from being run under more than just one program. A comparison of the results could then be performed to determine variations among the modeling software programs and attempt to gauge w hich results are the most realistic and plausible, thus enhancing the credibility of the study. It could also have proven beneficial to run different combinations of efficiency measures in the cumulative or â€œcascadeâ€ portion of modeling. Certain efficiency measures could have been excluded
132 in this case or they could have been paired in various ways to determine any differences in savings not apparent in this project. The res earcher also questions the role that air leakage and duct performance had to play in the commercial scenario, as this was not a measure that could be improved upon in eQUEST in an attempt to generate energy savings , but is typically found to be an important factor in improving a buildingâ€™s efficiency . More research would also be cond ucted to obtain accurate pricing for the efficiency upgrades to the existing commercial building. This was not undertaken in this project due to informational constraints that would have led to presentation of potentially unrealistic or incorrect informat ion , so this portion of the project was focused on the ability of the energy efficiency measures to save energy and did not include a financial analysis for reference. I n future research, financial payback analysis could help strengthen the case for energ y efficiency upgrades if financial feasibility could be determined. As with the residential buildings, more information could have been gathered to ensure that the characteristics of this particular model fit in with average building characteristics in t he geographic location chosen, such as square footage, building materials, heating and cooling systems and sizing, among other factors. A survey of building characteristics in different locations would be conducted in the absence of temporal and informati onal constraints so that this model could be applied across many different locations and variations of energy efficiency savings could be determined for buildings across the country.
133 New Construction Commercial Building From this portion of the energy m odeling, it was determined that the commercial building with all high efficiency components used much less gas than even the most successfully retrofitted existing commercial building. This could be due to any number of factors, such as a more efficient s hell, highly efficient HVAC, and southfacing windows for passive solar heating. However, the electricity consumption was only around 1,000 kWh per month less than the baseline existing commercial building. This could be due to the fact that there were m inimal changes made to user behavior inputs, like thermostat management and lighting loads. In addition to this, the electricity consumption in the â€œmiscellaneous equipmentâ€ categor y m entioned in Chapter 5 was generated by eQUEST based on additional heating and cooling loads. If the two buildings were assumed to have comparable miscellaneous equipment, then the loads associated with it would also be similar . Other unknown contributions to this same category may have artificially inflated the overall electricity consumption, or at least reduced the ability for electricity consumption to be reduced overall based on the other high efficiency factors that were modeled. The same general findings concerning minimally reduced electric consumption and decreased gas consumption were also found in the second and third models that were run, where reduced numbers of windows were modeled on the north, east and west facing walls. In these scenarios, the electricity consumption associated with cooling was reduced likely due to decreased solar heat gain in the summer months, while electricity consumed by lighting was increased because of the decreased capacity of the building to admit natural daylight. Gas consumption associated with space heat ing was reduced as the number of
134 windows on these walls decreased, which could likely be due to reduced heat loss in the winter months. Overall, it can be concluded that the commercial building designed with highefficiency features in place uses less gas, but the electricity consumption varies and was found to be higher than some of the scenarios run for the existing commercial building. This could be at least partly attributed to an error in the modeling software or user error if certain components wer e entered incorrectly or not accurately modeled together. Future Improvements Many alterations could be made to this component of the energy modeling in the future aside from the utilization of a different, or multiple, energy modeling software programs. More combinations of high efficiency features would be run in future iterations of this research, such as different types of insulation, HVAC systems, window and door types, occupant loads, and water heater characteristics. More experimentation could have also been conducted o n user behavior, especially since it seemed from the existing commercial scenario that building energy management can potentially make a substantial difference in the energy needs of a commercial building. For the scope of this project, however, it was not practical to run a large variety of combinations of efficiency measures to determine which would consume the least amount of energy. Future research would also include pricing for a financial analysis that could make a more soli d case for designing a commercial building for efficiency. Fortunately,
135 a growing body of research is being developed which includes case studies as well as energy modeling scenarios and provides more in depth financial analysis than this report can provi de. Overall Conclusions and Future Improvements It was found that energy efficiency measures, techniques and technologies do have a great capacity for reducing energy consumption in buildings. The application of these building components varies between residential and commercial buildings, and between existing and new construction buildings, as do their effectiveness in reducing energy consumption. The appropriateness of different efficiency measures can be judged based on research and energy modeling, however their effectiveness can only be truly meas ured when they are applied in real life, and energy and monetary savings, as well as occupant comfort, are realized. In this particular research project, the energy efficiency measures, techniques and technologies that were modeled were limited by the capabilities of the energy modeling software programs chosen. The results of these modeling scenarios are in no way comprehensive, nor will they necessarily apply in every building in any given location. It should be noted that there were clear differences between the two energy modeling software programs used in this research, REM/ Rate and eQUEST. The former program had much more capabilities in terms of varieties of energy efficiency upgrades that could be applied to the building, as well as the ability to model multiple upgrades in conjunction with each other which seemed to give a clearer picture of energy savings associated with a full project of ret rofits . eQUEST was able to model cumulative savings associated with multiple efficiency improvements, but this did not
136 seem to be the default use for the software. This distinction seems fitting in many ways to residential applications, because often times in residential buildings more than one retrofit is implemented at once, especially if greater energy savings are desired and if a combination of certain energy efficiency upgrades proves cost effective. It may not necessarily be a commercial building ownerâ€™s interest to take a variety of different routes to achieve energy efficiency, but perhaps just one or two building improvements that have the greatest impact in energy reduction. This could be partially due to the substantially higher costs of retrofitting commercial buildings, which are much larger than residential and are therefore inherently more expensive to retrofit. eQUEST also had much greater capabilities than REM/ Rate insofar as HVAC equipment details was concerned, which implies that HVAC systems are potentially a much more critical component to improving building performance and reducing energy consumption and costs in commercial buildings due to the size of these sys tems. This serves to illustrate the differences between the types of energy efficiency upgrades that can best benefit residential and commercial buildings due to differences between these building types, which should be paid close attention to. Future i mprovements and expansions to the scope of this research would firstly include running the energy models in more than two software programs to discover any differences between energy modeling programs. A more detailed survey of building characteristics wo uld also be performed to acquire the most commonly found characteristics for use in energy modeling. This information would be used to model various levels of existing building efficiency based on the characteristics. More cost data would also be gathered for all building types to run financial analyses for each scenario,
137 and the geographic region of the scenario would also be expanded in future iterations. The passive elements and loads in the new construction buildings would also be balanced to ensure mor e optimal energy modeling. Different combinations of improvements would also be run for the existing commercial building, and more variations for different elements of the new construction commercial building would also be run. The undertaking of any of these improvements could help greatly expand the scope of this research and widen the potential for real life application of the results. The building sector has a very large potential for reducing energy consumption. It is the single biggest consumer of energy in the world, and the majority of that energy consumption is associated with day to day operation. There are clearly an abundance of measures that can be taken in buildings to reduce operation energy usage, which stands in support of efficiency and environmental goals everywhere. The improvement of building efficiency leads to lower energy bills because of lower energy consumption, which causes decreases in fossil fuel combustion, reducing pollution and the accumulation of greenhouse gases in the atmosphere. The more highefficiency buildings there are, the less damage is done to the environment globally. One of the only barriers to implementation of building efficiency measures is cost, which can be overcome in a variety of ways. Federal, state, and local governments can incentivize energy efficiency improvements by instituting rebate or tax credit programs. Subsidies can be placed on expensive highefficiency measures to help achieve affordability; the more highefficiency measures that are bought, the lower the prices can become in the marketplace. Governments can also mandate efficiency standards on buildings and remove subsidies on fossil fuels, which would incentivize building owners to improve
138 building efficiency and consume less energy. The U.S. federal government has sponsored programs to promote the improvement of building energy efficiency. In 2009, the DOE announced the rollout of the â€œRetrofit RampUpâ€ program, which was meant to kick start energy efficiency programs throughout the nation (DOE, 2009). The Department of Energy also sponsors the Database of State Incentives for Renewables and Efficiency (DSIRE), which allows the user to find state and federal incentives programs, many of which are related to building efficiency (DSIRE , n.d). Also, the U.S. Department of Housing and Urban Development (HUD) has worked with the EPA to promote Energy Star standards in new housing construction (HUD, n.d). As the price of energy increases, the feasibility of improving building efficiency through these types of programs becomes increasingly relevant. It is hoped that more programs supporting building efficiency will be developed in the coming years to contribute to the reduction of energy consumption in the building sector, a critical key to to reducing our overall impact on the environment , because buildings are everywhere; they are an integral and inescapable part of modern human life. Where one sees buildings, they are almost certainly known to have been put there by people. Buildings have evolved over time in many ways, and they have improved in just as many ways. This will undoubtedly continue. We may not know what future buildings will look like, but we do know that they will be efficient; this trend is already underway. It can and will continue as long as the field is improved upon and furthered and expanded worldwide, until highly energy consumptive buildings become a thing of the past.
139 A PPENDIX I: E XISTING RESIDENTIAL BUILDING INPUTS ANALYSES AND RESULTS Existing Residential Building Location and Automated Characteristics Electricity Characteristics
140 Gas Characteristics Basic House Characteristics
141 Slab Properties Floor Properties
142 Above Grade Wall Properties Windows Properties
143 Exterior Door Properties Ceiling/Attic Properties
144 Heating System Inputs
145 Cooling System Inputs
146 Water Heating Inputs
147 Duct System Inputs Whole House Air Infiltration Inputs
148 Appliance Inputs
149 IECC Mandatory Requirements DOE Zero Energy Ready Home Inputs
150 Drywall Thickness Input Existing Residential Analysis and Results Screenshots Energy Analysis Area Analysis
151 Existing Residential Efficiency Improvement Package Full Results â€œTotal Packageâ€ Results
156 â€œBase Packageâ€ Results
159 â€œShell Packageâ€ Results
162 â€œAppliance Packageâ€ Results
166 A PPENDIX II: N EW CONSTRUCTION RESIDENTIAL BUILDING INPUTS, ANALYSES AND RESULTS Utility Information Building Input Type
167 General Building Information Skip foundation walls Slab Floor Properties Skip Rim and Band
168 AboveGrade Wall Window and Glass Door Properties 55x35 windows (13.5 SF per window) South:
169 North: East: West:
170 Doors: Ceiling: Mechanical Equipment:
172 Whole House Infiltration Appliances IECC Mandatory Requirements
173 DOE Zero Energy Ready Home Interior Mass Analysis Results
174 Variations: Southeast facing windows Results:
175 Southwest Facing Windows: Results:
176 Window Amount: 4 Southfacing 8 Southfacing windows
177 16 Southfacing windows 20 south facing windows
178 24 south facing windows: HVAC (geothermal)
179 Integrated Space/Water heating
180 APPENDIX III: EXISTING COMMERCIAL INPUTS, ANALYSES AND RESULTS
190 Skips from 27 to 36
192 Creation of Energy Efficiency Measures
198 Results: Baseline Design Consumption:
199 With Roof Insulation:
200 With Exterior Wall Insulation:
201 With Ground Floor Insulation:
202 With Window Replacement: With Window Shades:
203 With Daylighting Controls
204 With Thermostat Management: With High efficiency HVAC:
205 With Efficient DHW
216 APPENDIX IV: NEW CONSTRUCTION COMMERCIAL INPUTS, ANALYSES AND RESULTS Run 1:
231 Run 1 Results:
233 Run 2: Fewer windows on North, east and west walls
235 Run 3: Even fewer windows on the north, east and west walls
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247 LIST OF FIGURE REFERENCES Figure 2.1â€”Data retrieved from http://www.eia.gov/totalenergy/data/monthly/pdf/sec2_3.pdf Figure 2.2â€”Data retrieved from http://www.eia.gov/totalenergy/data/monthly/pdf/sec7_19.pdf Figure 2.3 â€”Data retrieved from http://www.eia.gov/environment/data.cfm#summary Figure 4.1â€”Image retrieved from http://energy.gov/sites/prod/files/guide_to_energy_efficient_windows.pdf Figure 4.2â€”Image retrieved from http://energy.gov/sites/prod/files/guide_to_energy_efficient_windows.pdf Figure 4.3â€”Data retrieved from Randolph, J., & Masters, G. (2008). Energy for sustainability: Technology, planning, policy (p. 231). Washington, D.C.: Island Press. Figure 4.4â€”Image obtained from http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulati on_table Figure 4.5â€”Image obtained from http://www.eia.gov/todayinenergy/detail.cfm?id=3690 Figure 4.6â€”Image obtained from http://www.energystar.gov/ia/partners/prod_development/new_specs/downloads/ water_heaters/Water_Heater_Market_Profile_2010.pdf?05442a1e Figure 4.7â€”Image obtained from Randolph, J., & Masters, G. (2008). Energy for sustainability: Technology, planning, policy (p. 27 1 ). Washington, D.C.: Island Press. Figure 5.1â€”Image obtained from REM/ Rate Figure 5.2â€”Image obtained from REM/ Rate Figure 5. 3 â€”Image obtained from REM/ Rate Figure 5.4â€”Image obtained from REM/ Rate Figure 5.5â€”Image obtained from REM/ Rate Figure 5.6â€”Data obtained from REM/ Rate
248 Figure 5.7â€”Image obtained from REM/ Rate Figure 5.8â€”Image obtained from eQUEST Figure 5.9â€”Image obtained from eQUEST
249 BIOGRAPHICAL SKETCH Jillian Becker graduated with honors from James Madison University in 2011 with a Bachelorâ€™s of Science in Integrated Science and Technology, with concentrations in Energy and Environment. She has spent the last four years working as the energy efficiency manager for a home energy auditing company based in Rockville, Maryland. She currently lives in Virginia Beach, Virginia with her significant other, Randy, and their two dogs, Jenny and Toby.