Real Prospects for Energy Efficiency in the United States (2010) / Chapter Skim
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2 Energy Efficiency in Residential and Commercial Buildings
2 Energy Efficiency in Residential and Commercial Buildings
Pages 41-120
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From page 41... ...
2.1 ENERGY USE IN BUILDINGS In 2006, residential and commercial buildings accounted for 39 percent of the total primary energy used and 72 percent of the electricity used in the United States to supply power and fuel for heating, cooling, lighting, computing, and other needs. As Figures 2.1 (residential buildings)
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7% Other 13% Heating, Ventilation, and Air-Conditioning Cooking 2% 32% Refrigeration 4% Electronics and Computers 12% Water Heating 6% Lighting 25% FIGURE 2.2 Energy use in U.S. commercial buildings by end-use, 2006.
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From page 43... ...
of floor space in 5 million commercial buildings as of 2006 (EIA, 2008b)
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. Residential energy intensity, defined as energy use per square foot of liv ing space, declined over the past 30 years in spite of the growing penetration of 1 "Delivered" energy refers to the electricity delivered to a site plus the fuels used directly on site (e.g., natural gas for heating water)
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Data for 2005 are from 2005 Residential Energy Consumption SurveyDetailed Tables, available at http://www.eia.doe.gov/emeu/recs/recs2005/hc2005_ tables/detailed_tables2005.html. appliances (see discussion below)
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Primary energy use (accounting for losses in electricity generation and transmission and distribution andEfficiency such as 2.5 for fuels, natural gas, used on-site) has increased faster than delivered energy use (which does not account for such losses but does include fuels used on-site)
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Residential energy use varies by household income, as shown in Table 2.2. Upper-income households earning more than $100,000 annually in 2001 used about twice the energy used by lower-income households earning under $15,000 annually.
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. In housing, space heating represented about 48 percent of total energy TABLE 2.3 Commercial Sector Energy Intensity Trends Delivered Primary (1000 Btu/ft2)
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Space heating in commercial buildings in 2005 accounted for 24 percent of delivered-energy use and 14 percent of primary energy use, on average. Lighting accounted for about 17 percent of delivered-energy use and more than 25 percent of primary energy use, on average.
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Likewise, the average efficiency of other products, including air conditioners, gas furnaces, clothes washers, and dish washers, has improved significantly over the past 30 years. Yet progress has been minimal for other products, such as water heaters.
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350 300 250 200 150 100 50 0 2000 2001 2002 2003 2004 2005 2006 2007 Year FIGURE 2.6 Shipments of compact fluorescent lamps. Source: U.S.
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The increase in the use of energy-efficient lighting devices such as CFLs, electronic ballasts, and specular light reflectors is most noteworthy. At the same time, a significant fraction, and in some cases a majority of commercial buildings, still do not use common energy efficiency measures such as energy management and control systems or HVAC economizer cycles (which make use of outdoor air for cooling when temperature and humidity levels permit)
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From page 53... ...
TABLE 2.7 Growth in the Use of Energy Efficiency Measures in Commercial Buildings Percentage of Floorspace with Measure Efficiency Measure 1992 2003 HVAC economizer cycle 27 33 HVAC variable air volume system 21 30 Energy management and control system 21 24 Compact fluorescent lamps 12 43 NAa Electronic lamp ballasts 72 Specular light reflectors 22 40 Multipaned windows 44 60 Tinted or reflective window glass 37 59 NAa Daylighting sensors 4 aNA, not available. Source: Energy Information Administration, 00 Commercial Buildings Energy Consumption Survey: Building Characteristics Tables and Commercial Buildings Characteristics , both available on the EIA website.
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From page 54... ...
Section 2.5 presents conservation supply curves for both residential and commercial buildings. This section presents a review of what the Panel on Energy Efficiency Tech nologies believes is a representative sample of the most credible such studies.
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This section looks most closely at the economic potential: that is, how much potential there is for energy savings at prices of energy up to or moderately above current or projected electricity market prices. The economic potential as assessed in any study depends on the following: how many end-uses are examined in detail (since it is hard to posit a supply curve for saved energy from the "miscellaneous" or "other" categories of energy use)
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(Note that the natural-gas savings potential suggested by these studies is less than that indicated TABLE 2.8 Summary of Results from the ACEEE Meta-Analysis: Studies of the Potential for Energy Savings in Buildings, 2000–2004 Potential (%) Region Year No.
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For natural gas, savings potentials appear to be higher in the residential sector than in the commercial sector. The median technical potential for gas savings across the studies is 48 percent in the residential sector and 20 percent in the commercial sector.
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But new efficiency measures continue to be developed and to add to the long-term efficiency potential. This trend is illus trated by comparing two studies on available electricity-savings opportunities that were prepared for New York State in 1989 and 2003 (see Figure 2.7)
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Further information on utility DSM programs is provided in Chapter 5. A study of the energy savings to date by sector in New York State relative to the potential savings that were identified reveals that the greatest energy efficiency potential for buildings remains in the residential sector, despite recent achieve
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But the question of how much efficiency is available at what price is not well framed, because the meaning of "available" is ambiguous with respect to several critical issues: • The timeframe over which the potential is available. The efficiency potential within 3 years from retrofitting homes is a very different pol icy question from the potential within 30 years from retrofitting homes, both in terms of the number and the type of efficiency measures that can be implemented.
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From page 61... ...
Likewise, heat-pump water heaters have been produced on a limited basis since the early 1980s. These devices use one-third to one-half as much electricity as that used by electric-resistance water heaters, with the energy savings paying back the incremental first cost in 5 years or less (Ashdown et al., 2004)
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From page 62... ...
in regulated energy use (heating, cooling, air-conditioning, water heating, and lighting) .4 Reviews of highly efficient commercial buildings (NBI, 2008; ASHRAE, 2008; Torcellini et al., 2006)
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Experience shows that in order to maximize real-world energy savings, it is critical to properly commission and monitor the performance of low-energy buildings and to ensure that control systems are working properly and are adjusted to account for occupancy conditions (Torcellini et al., 2006; Mills, 2009)
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Similar energy-saving measures and strategies can be applied to both. These efficiency measures and strategies include the following (Scheckel, 2007; Amann et al., 2007)
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From page 65... ...
• Making greater use of passive solar heating and cooling, although this design technique has not yet found widespread acceptance in the mar ketplace owing to the difficulties of custom designing the orientation and thermal characteristics of each home. After space heating and cooling, the next-largest user of energy in residences is water heating.
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From page 66... ...
Studies of energy efficiency potential usually look at specific measures within these categories, such as improving the rated efficiency of rooftop air conditioners by 20–30 percent or substituting 100 lumen per watt lamp-ballast combinations for existing product combinations that provide fewer than 70 lumens per watt. 2.4.3 Approach by Individual "Widgets" or Detailed Energy Efficiency Measures The energy end-use approach to estimating potential savings suffers from the lim ited ability of readers to review critically the assumptions that are made and the models that are used to derive the costs and savings for specific energy efficiency measures.
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However, the results are easier to review and validate and may thus be more credible. The discussion of whole-building-based analysis noted that a number of commercial buildings achieve 50 percent savings with no increase in first cost.
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2.5.1 Methodology and Efficiency Measures To calculate cost-effective energy-savings potential in 2030, Brown et al.
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(00¢/kWh) Space heatingc 164 17 28 3.5 Space coolingc 328 27 89 5.3 Water heatingc,d,e 149 27 39 2.0 Refrigerationc 121 31 38 4.6 Cookingc,e 103 0 0 N/A Clothes dryersc,e 103 0 0 N/A Freezersc 42 21 9 7.4 Lightingc 338 50 169 1.2 Clothes washersc 9 50 4 2.3 Dishwashersf 11 11 1 5.8 Color televisionsc 267 25 67 0.9 Personal computersf 68 57 39 4.3 Furnace fansf 40 25 10 3.7 Other usesc 154 48 74 1.9 Total electricity 1896 30 567 2.7 Natural Gas (Quads)
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(00¢/kWh) Space heatingb 77 39 30 0.5 Space coolingb 238 48 115 2.8 Water heatingb 59 11 6 1.2 Ventilationb 131 45 59 0.5 Cookingc 11 30 3 8.3 Lightingb 543 25 137 5.2 Refrigerationb 89 38 34 1.3 Office equipmentPCsc 120 60 71 3.9 Office equipmentnon-PCsc 271 25 68 3.2 Other usesb 523 35 182 1.4 Total electricity 2062 34 705 2.7 Natural Gas (Quads)
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From page 71... ...
The CCE is reported as the levelized annual cost of the efficiency measures over their lifetime divided by the estimated annual energy savings. The CCE accounts for the costs of incremental measures only; no cost is included for public policies or programs aimed at stimulating the adoption of a measure.
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Real Prospects for Energy Efficiency in the United States TABLE 2.11 Residential Building Measures Included in the Conservation Supply Curve Analysis Fuel and End-Use Efficiency Measure Description Electricity Thermal shell Existing electric-heated homes: no efficiency measures; new homes: up to 40% savings compared to 2006 International Energy Conservation Code Space heating equipment Electric furnace switched to heat pump, improved heat-pump efficiency Space cooling equipment Improved-efficiency central and room air conditioners, variable speed room air conditioners Water heating Reduced standby-loss electric-resistance water heater, heat pump water heater, horizontal axis clothes washer Best-in-class ENERGY STAR® refrigerator, 2008 Refrigeration Best-in-class ENERGY STAR® freezer, 2008 Freezers Lighting Compact fluorescent fixtures, halogen-infrared lamps, reduced-wattage incandescents, motion sensors Clothes washers Horizontal-axis washer with improved motor Dishwashers Dishwasher with improved pump design and improved motor Color televisions Reduced standby power use ENERGY STAR®-rated PC and monitor, power-management-enabled Personal computers Furnace fans Electronically commutated permanent magnet furnace-fan motor, single-speed operation Other uses More efficient motors in ceiling fans, pool pumps, and other small motors; improved fan and pump design; reduced standby power use in set-top boxes and other electronics; improved insulation for water beds, spas, and other small heating loads Natural Gas Thermal shell Air sealing, R-19 floor insulation, R-21 wall insulation, R-49 attic insulation, integrated design for new construction (SF 30% > code, MF 50% > code) , triple-pane low-e windows, insulated attic hatch Space heating equipment Insulated/sealed/balanced ducts, ducts placed within thermal shell condensing furnace, sensible heat recovery ventilation, direct-vent fireplace, direct-vent boiler, programmable thermostat, boiler pipe insulation Space cooling equipment Not applicable Water heating On-demand water heater, 0.63 EF gas water heater, low-flow plumbing fittings, ENERGY STAR® clothes washer, reduced water heater tank temperature, gray water heat exchanger/GFX, pipe insulation Cooking Not applicable Humidity sensor control Other uses Pool and spa covers Source: Brown et al., 2008.
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In using these savings potentials to estimate the
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in New York is representative of the country as a whole. The CCE, however, depends on the absolute energy savings for a given measure, so Brown et al.
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Each step on the graphs in these two figures represents the total savings for a given end-use for all the costeffective efficiency measures analyzed for that end-use. These are referred to as "supply curves" because they indicate how much energy savings is available for a given cost.
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These averages are based on combining efficiency measures with CCE values ranging from less than 1¢/kWh to 8¢/kWh in the case of electricity saving measures, and $1/million Btu to $12/million Btu in the case of natural-gas-saving measures. There is an up-front cost to achieving substantial energy savings, but this cost is paid back a number of times over the lifetime of the energy efficiency measures.
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and energy savings poten tial for natural gas efficiency technologies in buildings in 2030. The CCEs for potential energy efficiency measures (numbered)
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, which reflects technology and market con ditions in the late 1990s. Clearly, many factors have changed since then, including new technologies becoming available as well as costs falling for some energy efficiency measures owing to improved manufacturing processes, increased volumes, and the relocation of manufacturing facil ities to countries where costs are lower.
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. • As explained in Section 2.5.2, it is assumed that new efficiency measures compensate for the loss of savings potential due to measures adopted since 2000.
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These technologies and approaches add to the energy-savings potential identified in the conservation supply curves; thus, the panel judges that these supply curves repre sent lower estimates of energy-savings potential. This section reviews some of the advanced technologies that are the most promising for further improving the energy efficiency of buildings.
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From page 81... ...
2.6.1 Solid-State Lighting Solid-state lighting is an important emerging technology for energy savings, given that lighting accounts for about 18 percent of primary energy use in buildings. CFLs are a major improvement over incandescent lamps with respect to efficacy (about 60 lumens per watt versus 15 lumens per watt)
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. The model proj ects that LEDs will yield a 12 percent savings in lighting energy use in 2017 and a 33 percent savings by 2027, relative to projected lighting energy use without LEDs.
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and are much more speculative in view of impending technology hurdles and cost challenges. 2.6.2 Advanced Cooling Cooling is one of the largest uses of energy in residential and commercial buildings, responsible for about 10 percent of total U.S.
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Options for low-lift cool ing include the use of a dedicated outdoor air supply with enthalpy heat recovery from exhaust air, radiant cooling panels or floor systems, low-lift vapor compres sion equipment, and advanced controls. The technical energy savings potential is estimated to be 60–74 percent for temperate to hot and humid climates and 30–70 percent in milder climates (Jiang et al., 2007)
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(2005) estimate that the widespread adoption of advanced sensors and controls could reduce primary energy use by commercial buildings by about 6 percent.
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Many other kinds of appliances, such as dishwashers, furnaces, and water heaters, have electronic controls that are responsible for a small but noticeable fraction of those products' overall energy consumption. Electronic products typically consume energy both while active and while switched off.
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From page 87... ...
The EPA (2007b) estimates that with the more widespread adoption of costeffective energy efficiency technologies and practices already in use in some servers and data centers today, the overall electricity use of servers and data centers could be limited to 48 TWh in 2011, 55 percent less than in the current trends scenario.
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From page 88... ...
of windows through the use of low-emissivity (low-E) coatings and by reducing the solar heat gain coefficient (SHGC)
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The tables show that the full penetration of ENERGY STAR® windows in residential and similar windows in commercial buildings would provide nearly 1.8 quads of energy savings per year. However, if the advanced technologies described above are commercialized and fully penetrate the buildings stock, the full technical potential for energy savings would increase to nearly 3.9 quads per year.
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Source: Apte and Arasteh, 2006. TABLE 2.16 Annual Energy Savings Potentials of New Commercial Window Technologies Energy Savings over Installed Stock in 2005 (quads)
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Very little compressor cooling was ever needed. However, natural gas consumption totaled 700 million Btu per year -- likely due to excess heat loss in a hot-water circulation loop.
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The total incremental cost of the project was $42,500, including $32,000 for the PV system and $7,100 for the solar water-heating system. The incremental cost of the efficiency measures was only about $3,400, due in part to the elimination of a full-size furnace.
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From page 93... ...
. The efficiency measures that can be used to achieve this level of energy efficiency include additional insulation, tight sealing of the building envelope, highly efficient heating and cooling equipment, a tankless gas hot-water heater, ENERGY STAR® appliances, and fluorescent lamps in most light fixtures.
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energy use and first increase in incremental cost are a result of energy efficiency measures. The second drop in (conven tional)
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From page 95... ...
energy-using subsystems within such buildings are often redesigned on 5-year or 20-year cycles, so improved subsystems could be applied at least partially to exist ing buildings, particularly in the commercial sector. A review of the best-performing new buildings in the country suggests that buildings that achieve energy-use reductions of 50 percent or more below stan dard practice do not typically incorporate cutting-edge technologies, but instead successfully integrate multiple "state-of-the-shelf"14 technologies to achieve these performance levels (Turner and Frankel, 2008)
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To address this problem, a host of efforts are currently under way for developing more effective tools to monitor and manage building operational per formance using real-time data and intuitive data visualization.16 2.7 BARRIERS TO IMPROVING ENERGY EFFICIENCY IN BUILDINGS Proponents of energy efficiency point to a wide range of market failures or bar riers that inhibit greater investment in energy efficiency measures, including the following: 16Building performance measurement protocols are currently under development by the Cen ter for Neighborhood Technology, the New Buildings Institute, the Green Building Alliance, the U.S. Green Building Council, the American Society of Heating, Refrigerating, and Air-Condition ing Engineers, and a host of private companies.
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Market barriers are not flaws in the way that markets operate, but they limit the adoption of energy efficiency measures nonetheless. 2.7.1 Market Failures Environmental externalities are one of the most important and frequently cited examples of unpriced costs and benefits.
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. consumers face incentives to use more energy than is socially desirable if they do not bear the full costs of the pollution their energy use fosters." There are also barriers to recognizing and taking into account the full ben efits of energy efficiency measures in consumer decision making.
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From page 99... ...
For example, a survey in California found that insulation, energy-efficient windows, programmable thermostats, and other energy efficiency measures are less common in rental housing compared to owner-occupied dwellings (see Figure 2.14)
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In some cases the split in incentives is not between different economic actors but between different centers of responsibility within a single organization. In larger companies, energy efficiency investment decisions are often made by finan cial officers in charge of capital budgets, but the energy savings accrue to the divi sion responsible for operating a particular piece of energy-efficient equipment.
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. Indeed, many owners or managers of large commercial buildings have no knowledge of the size of the energy bills of their properties, despite the fact that energy is the largest cost component of net operating income, typically coming in at 15 percent.
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there was no standard on how to test a television's energy consumption. This type of problem often occurs because the product's trade asso ciation wants to set test standards or, in some cases, prefers that there not be any test standards.
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. Many individual consumers also do not value the lifetime energy savings provided by more efficient appliances, vehicles, or other energy efficiency measures.
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Moreover, there are transactions costs related to educating consumers, addressing the split incentives problem, or convincing households or businesses to invest in energy efficiency to a greater degree. The real question is whether policy and program interventions are cost-effective mechanisms for stimulating greater investment in energy efficiency measures -- that is, whether the value of the energy savings, peak demand reduction, and nonenergy benefits (see below)
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Higher energy prices improve the cost-effectiveness of energy efficiency measures and stimulate greater interest in and willingness to adopt such measures on the part of consumers (AIA, 2007)
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10 8 8 6 6 4 Electricity 4 Natural Gas 2 2 0 0 1973 1977 1981 1985 1989 1993 1997 2001 2005 Year FIGURE 2.15 Average price of residential natural gas and average retail price of residen 2.15 Efficiency tial electricity. Source: EIA, 2008b.
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From page 107... ...
For applications where lights are hard to change or where staff must be paid to change the bulbs, the value of reduced maintenance greatly exceeds the value of the energy savings.20 The color rendition of CFLs, which is different from that of incandescents, in some cases is a benefit. Incandescents are only available in a limited range of color temperatures from about 2500 K to 3000 K, with the low end of the range 20For example, to change incandescent lamps providing illumination to a three-story atrium, maintenance crews must set up scaffolding to climb up three stories in order to change the bulbs.
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From page 108... ...
Many of these products can also, through their energy-efficient design, handle larger garments or those that might previously have required dry cleaning. These factors are much more important than energy savings in the marketing of these clothes washers.
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From page 109... ...
Median predictions of achievable, cost-effective sav ings are 1.2 percent per year for electricity and 0.5 percent per year for natural gas, amounting to a 25–30 percent energy savings for the build ings sector as a whole over the next 20–25 years. If this level of savings were to be achieved, it would offset the EIA (2008a)
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With appropriate policies and programs, they could become the norm in new construction. B.5 Despite substantial barriers to widespread energy efficiency improve ments in buildings, a number of countervailing factors could drive increased energy efficiency, including rising energy prices, growing concern about global climate change and the resulting willingness of consumers and businesses to take action to reduce emissions, a move ment toward "green buildings," and growing recognition of the signifi cant nonenergy benefits offered by energy efficiency measures.
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Household Trends in Energy Intensity Indicators: A Look at the Underlying Factors. Washington, D.C.: Energy Information Administration.
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2006. Technical and economic assessment of solar thermal absorption cooling systems in small commercial buildings.
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2005. Impacts of Energy Efficiency and Renewable Energy on Natural Gas Markets: Updated and Expanded Analysis.
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Proceedings of the 2008 ACEEE Summer Study on Energy Efficiency in Buildings. Washington, D.C.: American Council for an Energy Efficient Economy.
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2007. Energy efficiency improvements that use the best available technologies and practices and integrated whole-building design approaches can, on average, reduce energy consumption by 43%.
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buildings sector: Results from the Clean Energy Futures Study. Energy Policy 29(14)
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2006. Energy Savings Potential of Solid State Lighting in General Illumination Applications.
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2003. Energy Efficiency and Renewable Energy Resource Development Potential in New York State.
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2005. Easing the Natural Gas Crisis: Reducing Natural Gas Prices Through Increased Deployment of Renewable Energy and Energy Efficiency.
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