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Rocky Mountain Institute’s Home Energy Briefs #4 SPACE HEATING

The 2004 edition of this Brief is made possible with generous support by Stonyfield Farm (www.stonyfield.com), the National Association of Realtors (www.realtor.org), the Durst Organization Inc. (www.durst.org), and Deborah Reich.

Space heating and cooling gas remains the most economical You can prevent this heat loss by account for 45 percent of total fuel choice for , , implementing passive heating home energy use and cost the and in-space heaters. Second, measures such as improving insu- typical family $677 a year.1 Space new technology (e.g., active solar lation, sealing leaks, and replacing heating alone costs the average heating and geothermal heat or reglazing your windows to mini- homeowner $480 per year, or pumps) might be an option if you mize . For more infor- about 32 percent of the total ener- live in certain climates. However, mation, see Home Energy Brief gy bill.2 In the Northeast, heating if you live in a small home or No. 1: . bills can reach $800 or more.3 apartment, supplementing your The good news is that everyone heating needs with in-space Making your home climate-smart can take action to save on heating heaters can also reduce energy so that it naturally harnesses solar bills. The space heating philoso- costs. This Brief will guide you energy (also called passive heat- phy among energy-efficiency on these home-heating options ing) can be expensive as a retrofit advocates is that a well-insulated, and covers: measure, and is discussed in tightly-constructed home requires Home Energy Brief No. 9: Whole little supplementary heating, and • Heat loss and passive heating; System Design. Recommended retrofit measures that minimize • The efficiency of various heat- retrofit measures include installing heat loss reduce heating require- ing systems, their maintenance large south-facing windows, ments even in old, leaky homes. requirements, and their costs; adding south-facing • Sizing and installation of new walls, and installing a sunroom. Once you have properly insulated heating systems; and and sealed your home, there are • Considerations about when to several space-heating-related replace your existing heating SPACE HEATING things you can do to make your system. SYSTEMS home more efficient depending The most common heating systems on your existing , are furnaces, boilers, and space your climate, and the size of your HEAT LOSS AND heaters. New technologies, such home. First, although it is a non- PASSIVE HEATING as geothermal heat pumps and renewable fossil fuel, natural Heat naturally flows from warmer active solar heating systems, are spaces to cooler ones until the also available. This section will temperatures both in and between briefly describe these different Other titles in Rocky Mountain Institute’s the two spaces are equal. Inside heating systems, their efficiencies, include: Home Energy Briefs the home, warm air rises and leaks maintenance issues, and costs. No. 1 Building Envelope out the attic and roof while draw- No. 2 Lighting No. 3 Space Cooling ing cold air in through the base- No. 4 Space Heating ment. Your home’s shell (walls, No. 5 windows, doors, foundation, roof, For additional information, as well as a downloadable No. 6 Cleaning Appliances attic, etc.) determines its rate of version of this document, No. 7 Electronics heat loss, and leaky shells can be please see our website: No. 8 Kitchen Appliances responsible for 25–40 percent of www.rmi.org No. 9 Whole System Design This document was last updated: 1/10/06 the load on your heating system.4 2

RMI’s Briefs: Home Energy Furnaces (air systems) to maintain comfortable indoor and boilers (hot water temperatures. The advantages of What is the AFUE? or steam systems) boilers include the ability to regu- The efficiency of a heating late the temperature in each room, system is measured by the Furnaces and boilers are the most Annual Fuel Utilization common types of heating systems. the avoidance of heat loss through Efficiency: the percentage

#4 Space Heating If you own a or you ducted air systems, and the use of of fuel that is converted to can save energy by improving the same boiler for domestic hot heat, factoring in combus- the efficiency of your system water (see Home Energy Brief No. tion, seasonal use, and through better maintenance and 5: Water Heating). However, boil- on/off cycling. A heating ers can be slow to warm up and, system technician can minor modifications. A typical gas estimate the AFUE of furnace burns to heat unlike ducted air, cannot filter air your heater. air inside a winding pipe assembly or ventilate your home. Furnaces called a . Cool have the additional advantage of indoor air mixed with some out- using existing air ducts for central door supply air is then blown . The diagrams across the heat exchanger with a below show how conventional fur- , warming the air, which is then naces and boilers operate. However, this entails converting distributed via ducts throughout non-renewable fossil fuels to elec- the home. As such, these systems Efficiency: The federal minimum tricity in power stations that are are also called “ducted warm-air” efficiency standards for furnaces typically only 35 percent efficient, or “forced warm-air” distribution took effect in 1992, requiring that and this conversion combined with systems. An electric furnace is new furnaces have an AFUE of 78 regular furnace inefficiencies, similar to a gas furnace except percent and new boilers have an such as heat losses from ducts, it uses an electric coil or rods AFUE of 80 percent. The most makes electric furnaces an expen- instead of a heat exchanger to energy-efficient new furnaces sive option. warm incoming air. rated by the U.S. Environmental Protection Agency (EPA) under the The table on the following page A gas boiler heats water or steam voluntary Energy Star® label have briefly describes the features of a instead of air, which is then circu- an AFUE of 90 percent or higher. highly efficient furnace and boiler. lated through pipes to radiators or Energy Star-rated boilers have an The aim is to reduce the amount of baseboards in the home. Various AFUE of 85 percent or higher. escaping heat, extract more heat controls such as and Electric furnaces convert 100 per- from by-products, and valves turn the system on and off cent of to heat. improve on/off cycles.

Figure 1: Typical gas furnace (left) and schematic (right) of a boiler

radiator vent connector warm air to house vent floor heat exchanger draft hood naturally hot water boiler aspirating main shut-off valve circu- gas burner lating circulating fan motor pump cold-water water supply return cool air return pressure-reducing valve drain cock

Source: Home Energy Magazine Online, March/April 1996, http://homeenergy.org/archive/hem.dis.anl.gov/eehem/96/960309.html (left). Pahl, Greg, Natural Home Heating, p. 21. Reprinted by permission of Chelsea Green Publishing (right). 3

Maintenance: There are a number • Clean or change air filters nozzle (oil) or orifice (gas) size, RMI’s Briefs: Home Energy of things you can do to improve the (furnaces): When dust blocks installing a new burner and a efficiency and life of your furnace airflow, fans have to work harder motorized damper (see or boiler: which, in turn, drives up energy below), or replacing the pilot consumption and raises bills. light with an electronic ignition. • Seal leaky ducts (furnaces): For under $10 you can buy a Ask them to explain and quantify

Leaky ducts are notorious for reusable filter that lasts 1–2 AFUE improvements if possible. #4 Space Heating decreasing the efficiency of years. It should, however, be • Install a vent damper in the flue: warm-air furnaces and typically vacuumed monthly. Disposable By shutting the vent during the decrease their efficiencies by filters are also available from 6 off cycle, the damper prevents 20–30 percent. Seal joints hardware stores. and seams with mastic, and heat from being drawn up the insulate hot air ducts that pass • Install radiator reflectors flue and lost outside. (boilers): This avoids heat trans- through unheated spaces with • Install zone control radiators: fer from the radiator to the adja- fiberglass. Your boiler distribution system cent exterior wall. You can make • Insulate supply and return pipes can be retrofitted to provide reflectors from foil-covered zone control for different areas (boilers): Hot water and steam cardboard, which is available pipes passing through unheated of large homes. The old, large at many building supply stores. cast iron radiators can be areas should be wrapped with The reflector should be installed insulation. For steam pipes with replaced with space conserving behind your radiator and be the baseboard radiators, wall-hung wall thicknesses of at least three same size as it or slightly larger. inches, use high temperature- radiators, or fan coils. rated pipe insulation, such as • Clean registers (furnaces): • Install a programmable thermo- fiberglass. Foam insulation with Warm-air registers should be stat: These cost $30–100 and a thickness of a half-inch is suit- cleaned regularly and not ob- allow you to pre-set a heating able for hot water pipes. structed by drapes or furniture. schedule while maintaining • Manage the pilot light: Newer • Ensure thorough servicing: comfortable temperatures gas furnaces and boilers are Gas furnaces and boilers should (remember, look for the Energy equipped with electronic igni- be tuned every two years while Star label). You can turn the heat tions, which save $30–40 annual- oil units should be tuned annu- down during sleeping hours and ly in gas bills. If you have an ally. Make sure the technician when the home or rooms are older model and can safely turn tests the vent for leaks; leaky unoccupied. You’ll shave 2 per- the pilot on and off yourself, con- vents can let combustion gases cent off your heating bill with sider turning it off in the warmer into the home. They may also every degree that you lower the seasons for additional savings recommend efficiency modifi- . For example, turning ($2–4 per month). cations such as reducing the it down from 70ºF to 65ºF at night and back up to 75ºF during the 7 Table 1: Characteristics of a high energy-efficient day can save $80–100 per year. furnace or boiler

An additional heat exchanger through which hot flue gases pass Cost: The cost of a furnace or boil- second heat after leaving the conventional heat exchanger, thus capturing more er depends on the size of the sys- exchanger combustion energy from the source fuel tem and the installation require- ments. Most boilers and furnaces A device installed at the end of the draft hood of an appliance that automatic automatically closes the vent when the furnace or boiler is off and have a heating capacity of 40,000 vent damper restricts heated air from going up the vent to 300,000 Btus per hour, therefore you can expect to pay anywhere forced draft A mechanical system that moves flue gases through an appliance between $2,000 and $10,000, system and creates more efficient heat transfer in the heat exchanger including installation. Highly effi- intermittent Replaces the constantly-burning pilot light used in older models. cient models will cost more to ignition device When the thermostat calls for heat, the device produces a spark to purchase (and possibly install). (IID) light the pilot, which in turn lights the heating system’s main burner But because they will cost less to Electronically commuted motors are more efficient than standard fan operate, are typically cheaper in the ECM Fan blower motors for pushing heated air through the ductwork. People long run. To find out which manu- blower motor who like to run their furnace fans all year long for comfort or air (furnace) facturers are making the most effi- 5 cleaning reasons would save about $250 a year with an ECM motor cient furnaces and boilers accord- Source: RMI compilation ing to size, heating capacity, and 4

RMI’s Briefs: Home Energy An easy way to understand this Figure 2: In-space heaters What is a Btu? concept is to stand in direct sun- Heating capacity in light on a cold day. The radiant Electric quartz heaters are British thermal units per energy from the sun warms you hour (i.e., the amount of reflector-focused energy needed to raise even though the air temperature heaters. They cost $40–70, and dual #4 Space Heating 1 pound of water 1 degree stays the same. Surface combus- tion radiant heaters include radiant wattage allows Fahrenheit). As a compari- two heat settings. son, 1 Btu is the heat given ceilings and floors and surface off by completely burning combustion room heaters. Low- a single match. intensity electric and gas infrared A free-standing (below) heaters, and high-intensity electric can heat several rooms. and gas infrared heaters, are A 30,000 Btu model would cost fuel source, and how much they about $1,000 plus installation. cost, refer to either the Energy examples of reflector-focused Star‚ website at www.energystar.gov radiant heaters. or the American Council for an Energy-Efficient Economy’s web- In-space heaters come in a range site at www.aceee.org. of shapes, sizes, and heating capacities, and they use a variety In-space heaters of fuels. The AFUE of electric heaters is 100 percent whereas In-space heaters are designed to Source: World Marketing (bottom) combustion heaters range from provide heating in small, specific 56 to 71 percent for standard mod- 5,000 Btu per hour, the maximum areas. They are often considered a els, and up to 82 percent for those allowed by industry safety stan- last resort in cases where central with efficiency features such dards. This is enough heat to warm heating systems are inappropriate as induced vents and automatic mid-sized rooms. Baseboard elec- or unavailable. However, when in- pilot lights. Most portable electric tric heaters are often installed in space heaters are used in homes heaters, such as electric quartz the wall or along the floor and can that are well-insulated or small, or heaters (pictured), generate up to generate up to 50,000 Btu per hour. in homes where only one or two rooms are occupied, they will allow you to lower the temperature of Table 2: Opportunities for improving the efficiency of in-space heaters your system, main- regular Built-in heating facilities (connected to gas or oil pipe) should be tain comfort, and use less energy. maintenance regularly serviced to maintain working order For example, air temperatures can be lowered 6ºF to 8ºF in homes that programmable Choose modulating thermostats to reduce overshooting and provide have radiant spot heating. On mild thermostats better comfort with less energy days, central heating can be turned Induced draft on vented systems to move flue gases through the combustion appliance and create more efficient heat transfer in the heat off altogether. efficiency exchanger

In-space heaters can be divided reset central Reduce thermostat by 3–8ºF when using an electric or gas radiant into convectors and radiant thermostat heater for comfort heaters. Convectors transfer heat from the or burner timers and Control radiant heaters with occupancy detectors and/or timer set- occupancy tings to minimize on-time while satisfying comfort needs into the air and circulate it through- detectors out the room. Baseboard heaters, wall furnaces, floor furnaces, and Minimize quantity and size of heaters by choosing heaters that focus most gas and oil room-heaters are sizing the heat appropriately for the task area geometry and surface tem- perature requirements examples of convectors. Radiant heaters predominately heat only pilot light Gas appliances should be installed with an automatic pilot light the objects (including people) at positioning Orient portable heaters to provide optimal heating which they are directed and not necessarily the air in the room. Source: RMI compilation 5

Newer technology: mates, however. Where tempera- RMI’s Briefs: Home Energy ® What is Energy Star ? electric air-source and tures fall below freezing, air ® Energy Star is an EPA- geothermal heat pumps source heat pumps typically backed program that sets require a back-up heating system. strict efficiency guidelines A is an electrical for home products. For device that extracts heat from one

products that meet these place and transfers it to another. Geothermal heat pumps #4 Space Heating guidelines, an Energy Star It transfers heat by circulating a According to the EPA, geothermal label, shown below, is often through a cycle of heat pumps can save the average placed on the product. Look alternating evaporation and con- homeowner 30–70 percent in heat- for this label on the product or in its specifications to densation. In winter, a heat pump ing costs and 20–50 percent in ensure you are purchasing a removes heat from the outside air cooling costs. This could save high-efficiency product. and transfers it inside the home. some homeowners up to $400 per In summer, the process is reversed. year or more. Geothermal efficien- Heat pumps are an economical cy is measured by a coefficient of and energy-efficient way to pro- performance (COP) for heating and vide space heating and cooling. energy efficiency ratio (EER) for You can even retrofit your existing cooling. Geothermal systems with Although they are cheap to install, distribution system (ducts or pipes) Energy Star labels will have a they are expensive to run, which with a heat pump. Residential heat COP between 3.3 and 3.6 and an makes them a less desirable pumps can be air-source (air-to- EER of 14.2–16.2. option. Natural gas in-space air) systems, which draw heat from heaters are self-contained heating the air, and ground-source (earth Geothermal systems operate effec- appliances that draw in combus- energy) systems, that draw heat tively in any climate, but the great- tion air and discharge the by-prod- from the ground or ground water. est operational savings are real- uct through a vent to the outside. Although both systems use elec- ized in climates that have extreme Note that unvented combustion tricity, more than three times the heating and cooling loads and gen- heaters should be avoided because energy they consume is converted erate high energy bills. They are their exhaust can leak indoors. into heating or cooling output. typically twice as expensive to Gas units are generally mounted on For additional information on heat install as other central heating the wall or are free standing, and pumps, see Home Energy Briefs options, and can cost anywhere both types are connected to a gas No. 3: Space Cooling and No. 5: from $7,500 to $15,000. The heating line. Most combustion heaters do Water Heating. capacity can reach up to 130,000 not require electricity unless they Btus per hour. Many utilities offer operate fans for better convective The efficiency of an air-source cash rebates to help lower these heat distribution. Natural gas heat pump is measured by its heat- high initial costs. heaters range in size from 5,000 to ing season performance factor New technology: 60,000 Btu per hour. (HSPF) and seasonal energy effi- ciency ratio (SEER). Federal stan- active solar dards require air-source heat heating systems pumps to have a minimum HSPF In contrast to passive solar sys- Figure 3: Geothermal heat pump of 6.8 and a minimum SEER of 10. tems, active solar systems use However, heat pumps with SEERs supplemental electrical equipment, around 14.0 and HSPFs around 9.0 such as pumps or fans, to move vertical loop system are usually available. Look for heat heat around your home. In an pumps with an Energy Star label. active system, solar collectors har- Air-source heat pumps typically vest the sun’s energy to heat either cost $1,500–5,000, depending on liquid or air that is then pumped or the size and installation, and have blown through pipes or ducts to a heating output of up to 120,000 your living space.8 Liquid systems Btu/hr. Air-source heat pumps are are similar to boilers in that they Source: Adapted from Tool Base Services, Geothermal Heat Pumps, www.toolbase.org/ only effective in moderate cli- can provide space heating and hot tertiaryT.asp?TrackID=&DocumentID=2093 6

RMI’s Briefs: Home Energy SIZING industry standards for correctly Figure 4: Active solar hot-air systems An active solar hot air system uses AND INSTALLATION selecting and installing equipment air as the medium for collecting and OF HEATING SYSTEMS are set out in Manual J (Residen- distributing solar heat for your home. Properly sized equipment and tial Load Calculation) and Manual installation optimizes the benefits S (Residential Heating and Cooling

#4 Space Heating collector of new or modified heating sys- Equipment Selection). Make sure tems. Oversized systems lead to your contractor is familiar with overuse of on and off cycles, these manuals and is licensed in surges in air or water pressure, your state, and expect to pay more blower and the accumulation of moisture for good service. in the heat exchanger, which can damage the unit over time. REPLACING A hot air Undersized systems won’t ade- HEATING SYSTEM: quately heat the home. When SOME CONSIDERATIONS control system requesting a size and installation quote for furnaces, boilers, perma- When is the right time? cold air nently mounted in-space heaters, If your furnace is older than and heat pumps, choose a con- 10–15 years, and your boiler is tractor that follows ASHRAE older than 20 years, then a new Source: Adapted from Pahl, Greg, Natural Home Heating, p. 69. (www..org) and Air Condi- heating system will be at least 30 Reprinted by permission of Chelsea Green Publishing tioning Contractors of America percent more efficient and will pay (www.acca.org) guidelines. This for itself in 5–10 years. If you have water, and some models combine will help ensure that climate, size, electric furnace or electric base- these systems. Hot air systems and orientation of the home, as board heating throughout your operate much like furnaces. Active well as heat loss from the building home, then switching to natural systems can be expensive to shell and occupant lifestyles are gas can save you money. Finally, install and require electricity to considered in the contractor’s cal- if your annual heating and cooling operate. An active system will not culations. Specifications and costs are astronomical, then con- provide all your heating needs, especially in cold, cloudy, northern Table 3: Guidelines for estimating AFUE of gas heating systems climates where a backup heating system is required. In fact, solar Type Description AFUE heating systems are often • Natural draft that creates a flow of combustion gases designed to work in combination conventional, older furnaces • Continuous pilot light 68–72% with other heating systems, which and boilers • Heavy heat exchanger offers a lot of flexibility. Active • Exhaust fan controls the flow of combustion solar heating systems are good air and combustion gases better choices in climates that have long mid-efficiency • Electronic ignition (no pilot light) heating seasons with high propor- furnaces and 80–83% boilers • Compact size and lighter weight to reduce tions of sunny days and above cycling losses average utility and fuel prices. • Small-diameter flue pipe Active solar heating systems cost high-efficiency • Condensing flue gases in a second heat between $5,000 and $18,000 and, furnaces and exchanger for extra efficiency 90–97%9 as with geothermal heat pumps, boilers • Sealed combustion the operational savings are excep- • Vent direct vent tional. There is also the option of • Sealed combustion 73–82% wall heater installing a one-room solar heater • Pilot light or electric ignition for about $800. To find out more, free standing • Vent 65–71% contact an experienced solar heat- room heaters • Pilot light or electric ignition or 82%* ing designer. * With induced vent.

Source: RMI compilation 7 sider augmenting your heating sys- • When the entire cycle of produc- alight, etc.), and costs to install, RMI’s Briefs: Home Energy tem’s capabilities with in-space ing, transporting, and using fuel maintain, and operate the system. heaters or looking into heat pumps is considered, natural gas is To simplify the selection process, delivered to the consumer with and active solar heating. these factors can be combined a total energy efficiency of Remember, your best investment about 90 percent, compared into the total cost of ownership choice is to properly insulate and with about 20 percent for elec- over a period of years. Table 4 #4 Space Heating seal your home. tricity. compares a selection of central • Natural gas heating systems and heating systems. Note that it does What fuel to use? appliances, such as stoves and not include in-space heaters or Natural gas is the most popular water heating systems, can be active solar heaters. Rather, it fuel for heating systems for among the most efficient avail- illustrates where one can expect several good reasons, including able, and natural gas burns costs and savings for certain heat- cleaner than oil and wood. the following: ing systems. Geothermal heat pumps are the most cost-effective • Natural gas is generally cheaper Should you upgrade than other fuels. For example, in to a new system with a option in some cases. California, where utility and fuel higher AFUE? Will you save by supple- is more expensive than in most If you are thinking of converting to other states, a small gas furnace menting central heating would cost $16–40 per month a more efficient heating system, with an in-space heater? to operate, whereas an electric you can calculate expected savings The energy efficiency of in-space furnace would cost $110 per by using Equation 1. To complete month to operate.10 the equation, you will need to know heaters is more a function of their your annual heating costs (look at ability to deliver heating when and where it is needed, rather than Annual savings by your gas and electric bills during Equation 1: merely the conversion efficiency of upgrading to a higher AFUE the last few heating seasons), the AFUE of your current heating sys- fuel to heat (AFUE). Energy savings Annual Savings = (A – B)/A × C tem (ask a heating system techni- from in-space heaters are derived from only heating the rooms you Where, A = AFUE of new (or upgrade) cian or use the guidelines in Table 3 equipment on previous page), and the AFUE of occupy regularly and allowing you B = AFUE of existing equipment the new heating system you are to lower your thermostat. If your C = Annual heating cost considering (ask a retailer or heat- central heating system is an elec- For example: ing system technician or use the tric furnace, it is almost certain Annual heating cost = $480 you will save money by using in- AFUE of existing conventional guidelines in Table 3). Then plug all gas furnace = 68% (0.68) three numbers into Equation 1 to space heaters. However, if you AFUE of new mid-efficiency estimate your annual savings. have a large family and need more gas furnace = 82% (0.82) than three in-space heaters oper- Annual Savings = (0.82 – 0.68)/0.82 × 480 = $82/year What do I need to know ating at one time, a central heating If would like to calculate expected savings when changing heating system may be as cost effective from switching between fuels and/or between systems? systems, the following websites are useful: as using in-space heaters. • Home Energy Magazine: http://hem.dis.anl.gov/eehem/96/960309.html When comparing heating systems, • Heating with Gas EnerGuide: you should consider safety (i.e., http://oee.rncan.gc.ca/publications/infosource/home propensity to leak gases, catch

Table 4: Typical life-cycle costs of three central heating systems11

Safety Installation cost Operating cost Maintenance cost Life-cycle cost

combustion-based A Concern Moderate Moderate High Moderate

air-source Excellent Moderate Moderate Moderate Moderate heat pump geothermal Excellent High Low Low Low heat pump

Source: Geothermal Heat Pump Consortium, www.geoexchange.org/about/compare.htm 8

RMI’s Briefs: Home Energy SUMMARY ADDITIONAL RESOURCES NOTES Investing in space heating systems Department of Energy, Office of 1–3. EIA (Energy Information Administration), “Residential Energy Consumption Survey: is an expensive and long-term Energy Efficiency and Renewable Consumption and Expenditure Data,” decision. Think carefully about Energy (EERE) — Comprehensive and (Washington, DC: EIA, 2001), www.eia.doe.gov/ your options. The first step is to useful selection of fact sheets on all emeu/recs/recs2001/detailcetbls.html#total. aspects of space cooling, including a 4. Minnesota Department of Commerce, “Saving #4 Space Heating determine whether (and where) complete Home Energy Booklet that Money With Trees” (St. Paul, MN: MN DOC, your home loses heat through its can be downloaded for free Undated), p.1, www.state.mn.us/cgi-bin/portal/ building shell. The second step is (www.eere.energy.gov/consumerinfo/ mn/jsp/content.do?subchannel=-536881511&id= -536881350&agency=Commerce. to improve the efficiency of your factsheets.html). 5. Pacific Gas and Electric Company, “Selecting existing heating system, especially American Council for an Energy- a Heating System for Your Home,” (Undated), if it is a furnace, a boiler, an Efficient Economy (ACEEE) — www.pge.com/res/energy_tools_resources/ heating/select. installed in-space heater, or a A nonprofit organization that focuses on advancing energy efficiency. 6. A.C.S. Hayden, “Choosing a Heating System heat pump. When purchasing a that Saves Energy,” Home Energy Magazine new heating system, think about They list today’s most efficient home (March/April, 1996), http://hem.dis.anl.gov/ appliances on their website your climate, the size of your eehem/96/960309.html. (www.aceee.org/consumerguide/ 7. DOE (Department of Energy), “Thermostats home, your budget, and local utility mostenef.htm). and Control Systems,” (Washington, DC: EERE, and fuel costs; and make sure 2004), www.eere.energy.gov/consumerinfo/ you weigh the cost of investment Natural Home Heating: heatcool/hc_thermostats.html. The Complete Guide to Renewable against the long-term costs to 8. Greg Pahl, Natural Home Heating: The Energy Options, Greg Pahl, Vermont: Complete Guide to Options, operate the system. Chelsea Green Publishing, 2003. (Vermont: Chelsea Green Publishing, 2003). www.chelseagreen.com 9. DOE, “Energy Efficient Gas Heating for the Home,” (Washington DC: EERE, 2004), www.eere.energy.gov/consumerinfo/ factsheets/nb3.html. 10. Flex Your Power (California Statewide Energy), “Energy Usage Costs for Household Appliances,” (Undated), http://fypower.org/res/energy_costs.html. 11. Geothermal Heat Pump Consortium, “Comparing Systems,” (Undated), www.geoexchange.org/about/compare.htm.

Contact your local utility or energy office for information on rebates that may be available in your area on the purchase of new energy-efficient appliances. This publication is intended to help you improve the resource efficiency of your home. You should use your best judgment about your home, and seek expert advice when appropriate. Rocky Mountain Institute does not endorse any products mentioned and does not assume any responsibility for the accuracy or completeness of the information in this Brief. Written by Ramola Yardi, Andy Smith, and Katherine Wang. © Rocky Mountain Institute 2004.

Briefs Nos. 1–9 in the Home Energy series are funded by Stonyfield Farm, the Durst Organization Inc., the National Association of Realtors, and Deborah Reich.

Rocky Mountain Institute (RMI) is an independent, entrepreneurial, nonprofit applied research center that fosters the efficient and restorative use of natural, human and other capital to make the world secure, just, prosperous, and life-sustaining. We do this by inspiring business, civil society, and government to design integrative solutions that create true wealth.

To request additional copies please contact Rocky Mountain Institute, 1739 Snowmass Creek Road, Snowmass CO 81654-9199 Telephone: (970) 927-3851 • Fax: (970) 927-4510 • Email: [email protected] • Website: www.rmi.org

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