Geothermal heat pumps (sometimes referred to as GeoExchange, earth-coupled, ground-source, or water-source heat pumps) have been in use since the late 1940s. Geothermal heat pumps (GHPs) use the constant temperature of the earth as the exchange medium instead of the outside air temperature. This allows the system to reach fairly high efficiencies (300%-600%) on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days.

While many parts of the country experience seasonal temperature extremes—from scorching heat in the summer to sub-zero cold in the winter—a few feet below the earth’s surface the ground remains at a relatively constant temperature. Depending on latitude, ground temperatures range from 45°F (7°C) to 75°F (21°C). Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer. The GHP takes advantage of this by exchanging heat with the earth through a ground heat exchanger.

As with any heat pump, geothermal and water-source heat pumps are able to heat, cool, and, if so equipped, supply the house with hot water. Some models of geothermal systems are available with two-speed compressors and variable fans for more comfort and energy savings. Relative to air-source heat pumps, they are quieter, last longer, need little maintenance, and do not depend on the temperature of the outside air.

A dual-source heat pump combines an air-source heat pump with a geothermal heat pump. These appliances combine the best of both systems. Dual-source heat pumps have higher efficiency ratings than air-source units, but are not as efficient as geothermal units. The main advantage of dual-source systems is that they cost much less to install than a single geothermal unit, and work almost as well.

Even though the installation price of a geothermal system can be several times that of an air-source system of the same heating and cooling capacity, the additional costs are returned to you in energy savings in 5–10 years. System life is estimated at 25 years for the inside components and 50+ years for the ground loop. There are approximately 40,000 geothermal heat pumps installed in the United States each year.

Types of Geothermal Heat Pump Systems

There are four basic types of ground loop systems. Three of these—horizontal, vertical, and pond/lake—are closed-loop systems. The fourth type of system is the open-loop option. Which one of these is best depends on the climate, soil conditions, available land, and local installation costs at the site. All of these approaches can be used for residential and commercial building applications.

Closed-Loop Systems

Horizontal

This type of installation is generally most cost-effective for residential installations, particularly for new construction where sufficient land is available. It requires trenches at least four feet deep. The most common layouts either use two pipes, one buried at six feet, and the other at four feet, or two pipes placed side-by-side at five feet in the ground in a two-foot wide trench. The Slinky™ method of looping pipe allows more pipe in a shorter trench, which cuts down on installation costs and makes horizontal installation possible in areas it would not be with conventional horizontal applications

Vertical

Large commercial buildings and schools often use vertical systems because the land area required for horizontal loops would be prohibitive. Vertical loops are also used where the soil is too shallow for trenching, and they minimize the disturbance to existing landscaping. For a vertical system, holes (approximately four inches in diameter) are drilled about 20 feet apart and 100–400 feet deep. Into these holes go two pipes that are connected at the bottom with a U-bend to form a loop. The vertical loops are connected with horizontal pipe (i.e., manifold), placed in trenches, and connected to the heat pump in the building.

Pond/Lake

If the site has an adequate water body, this may be the lowest cost option. A supply line pipe is run underground from the building to the water and coiled into circles at least eight feet under the surface to prevent freezing. The coils should only be placed in a water source that meets minimum volume, depth, and quality criteria.

Open-Loop System

This type of system uses well or surface body water as the heat exchange fluid that circulates directly through the GHP system. Once it has circulated through the system, the water returns to the ground through the well, a recharge well, or surface discharge. This option is obviously practical only where there is an adequate supply of relatively clean water, and all local codes and regulations regarding groundwater discharge are met.

Benefits of Geothermal Heat Pump Systems

The biggest benefit of GHPs is that they use 25%–50% less electricity than conventional heating or cooling systems. This translates into a GHP using one unit of electricity to move three units of heat from the earth. According to the EPA, geothermal heat pumps can reduce energy consumption—and corresponding emissions—up to 44% compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment. GHPs also improve humidity control by maintaining about 50% relative indoor humidity, making GHPs very effective in humid areas.

Geothermal heat pump systems allow for design flexibility and can be installed in both new and retrofit situations. Because the hardware requires less space than that needed by conventional HVAC systems, the equipment rooms can be greatly scaled down in size, freeing space for productive use. GHP systems also provide excellent “zone” space conditioning, allowing different parts of your home to be heated or cooled to different temperatures.

Because GHP systems have relatively few moving parts, and because those parts are sheltered inside a building, they are durable and highly reliable. The underground piping often carries warranties of 25–50 years, and the heat pumps often last 20 years or more. Since they usually have no outdoor compressors, GHPs are not susceptible to vandalism. On the other hand, the components in the living space are easily accessible, which increases the convenience factor and helps ensure that the upkeep is done on a timely basis.

Because they have no outside condensing units like air conditioners, there’s no concern about noise outside the home. A two-speed GHP system is so quiet inside a house that users do not know it is operating: there are no tell-tale blasts of cold or hot air.

Selecting and Installing a Geothermal Heat Pump System

Heating and Cooling Efficiency of Geothermal Heat Pumps

The heating efficiency of ground-source and water-source heat pumps is indicated by their coefficient of performance (COP), which is the ratio of heat provided in Btu per Btu of energy input. Their cooling efficiency is indicated by the Energy Efficiency Ratio (EER), which is the ratio of the heat removed (in Btu per hour) to the electricity required (in watts) to run the unit. Look for the ENERGY STAR label, which indicates a heating COP of 2.8 or greater and an EER of 13 or greater.

Manufacturers of high-efficiency geothermal heat pumps voluntarily use the EPA ENERGY STAR label on qualifying equipment and related product literature. If you are purchasing a geothermal heat pump and uncertain whether it meets ENERGY STAR qualifications, ask for an efficiency rating of at least 2.8 COP or 13 EER.

Many geothermal heat pump systems carry the U.S. Department of Energy (DOE) and EPA ENERGY STAR label. ENERGY STAR-labeled equipment can now be financed with special ENERGY STAR loans from banks and other financial institutions. The goal of the loan program is to make ENERGY STAR equipment easier to purchase, so ENERGY STAR loans were created with attractive terms. Some loans have lower interest rates, longer repayment periods, or both. Ask your contractor about ENERGY STAR loans or call the ENERGY STAR toll-free hotline at 1-888-STAR-YES for a list of financing options.

Economics of Geothermal Heat Pumps

Geothermal heat pumps save money in operating and maintenance costs. While the initial purchase price of a residential GHP system is often higher than that of a comparable gas-fired furnace and central air-conditioning system, it is more efficient, thereby saving money every month. For further savings, GHPs equipped with a device called a “desuperheater” can heat the household water. In the summer cooling period, the heat that is taken from the house is used to heat the water for free. In the winter, water heating costs are reduced by about half.

On average, a geothermal heat pump system costs about $2,500 per ton of capacity, or roughly $7,500 for a 3-ton unit (a typical residential size). A system using horizontal ground loops will generally cost less than a system with vertical loops. In comparison, other systems would cost about $4,000 with air conditioning.

Although initially more expensive to install than conventional systems, properly sized and installed GHPs deliver more energy per unit consumed than conventional systems.

And since geothermal heat pumps are generally more efficient, they are less expensive to operate and maintain — typical annual energy savings range from 30% to 60%. Depending on factors such as climate, soil conditions, the system features you choose, and available financing and incentives, you may even recoup your initial investment in two to ten years through lower utility bills.

But when included in a mortgage, your GHP will have a positive cash flow from the beginning. For example, say that the extra $3,500 will add $30 per month to each mortgage payment. The energy cost savings will easily exceed that added mortgage amount over the course of each year.

On a retrofit, the GHP’s high efficiency typically means much lower utility bills, allowing the investment to be recouped in two to ten years. It may also be possible to include the purchase of a GHP system in an “energy-efficient mortgage” that would cover this and other energy-saving improvements to the home. Banks and mortgage companies can provide more information on these loans.

There may be a number of special financing options and incentives available to help offset the cost of adding a geothermal heat pump (GHP) to your home. These provisions are available from federal, state, and local governments; power providers; and banks or mortgage companies that offer energy-efficient mortgage loans for energy-saving home improvements. Be sure the system you’re interested in qualifies for available incentives before you make your final purchase.

To find out more about financing and incentives that are available to you, visit the Database of State Incentives for Renewable Energy (DSIRE) Web site. The site is frequently updated with the latest incentives. You should also check with your electric utility and ask if they offer any rebates, financing, or special electric rate programs.

Evaluating Your Site for a Geothermal Heat Pump

Because shallow ground temperatures are relatively constant throughout the United States, geothermal heat pumps (GHPs) can be effectively used almost anywhere. However, the specific geological, hydrological, and spatial characteristics of your land will help your local system supplier/installer determine the best type of ground loop for your site:

Geology

Factors such as the composition and properties of your soil and rock (which can affect heat transfer rates) require consideration when designing a ground loop. For example, soil with good heat transfer properties requires less piping to gather a certain amount of heat than soil with poor heat transfer properties. The amount of soil available contributes to system design as well — system suppliers in areas with extensive hard rock or soil too shallow to trench may install vertical ground loops instead of horizontal loops.

Hydrology

Ground or surface water availability also plays a part in deciding what type of ground loop to use. Depending on factors such as depth, volume, and water quality, bodies of surface water can be used as a source of water for an open-loop system, or as a repository for coils of piping in a closed-loop system. Ground water can also be used as a source for open-loop systems, provided the water quality is suitable and all ground water discharge regulations are met.

Before you purchase an open-loop system, you will want to be sure your system supplier/installer has fully investigated your site’s hydrology, so you can avoid potential problems such as aquifer depletion and groundwater contamination. Antifreeze fluids circulated through closed-loop systems generally pose little to no environmental hazard.

Land Availability

The amount and layout of your land, your landscaping, and the location of underground utilities or sprinkler systems also contribute to your system design. Horizontal ground loops (generally the most economical) are typically used for newly constructed buildings with sufficient land. Vertical installations or more compact horizontal “Slinky™” installations are often used for existing buildings because they minimize the disturbance to the landscape.

Installing Geothermal Heat Pumps

Because of the technical knowledge and equipment needed to properly install the piping, a GHP system installation is not a do-it-yourself project. To find a qualified installer, call your local utility company, the International Ground Source Heat Pump Association or the Geothermal Heat Pump Consortium for their listing of qualified installers in your area. Installers should be certified and experienced. Ask for references, especially for owners of systems that are several years old, and check them.

The ground heat exchanger in a GHP system is made up of a closed or open loop pipe system. Most common is the closed loop, in which high density polyethylene pipe is buried horizontally at 4-6 feet deep or vertically at 100 to 400 feet deep. These pipes are filled with an environmentally friendly antifreeze/water solution that acts as a heat exchanger. In the winter, the fluid in the pipes extracts heat from the earth and carries it into the building. In the summer, the system reverses and takes heat from the building and deposits it to the cooler ground.

The air delivery ductwork distributes the heated or cooled air through the house’s duct work, just like conventional systems. The box that contains the indoor coil and fan is sometimes called the air handler because it moves house air through the heat pump for heating or cooling. The air handler contains a large blower and a filter just like conventional air conditioners.

The materials from which a building is constructed, as well as the systems and appliances installed there can dramatically affect the amount of energy that a building will consume over its lifetime. To help customers compare the potential impact of one to another, efficiency ratings have been devised for many building components and energy systems.

A variety of energy ratings now abound, which can be confusing to the consumers these ratings were intended to help. We will try here to end that confusion by explaining each of the ratings systems listed below in as simple a way as possible. Also included is a Glossary of Efficiency Terms.

Building Materials

The materials from which a building is constructed can have a marked impact on the structure’s efficiency. Materials that allow a lot of heat to pass through them lower the overall efficiency level of the building. Conversely, materials that resist a significant amount of heat transference can help ensure greater efficiency. The degree to which a building component (such as a window or wall system) transfers heat is referred to as its U-value. The ability of an inpidual material (for instance, glass, wood, metal) to resist heat transfer is called its R- value.

Appliances and Equipment

When referring to the efficiency of an appliance or energy system, we are actually talking about how much energy that system must use to perform a certain amount of work. The higher its energy consumption per unit of output, the less efficient the system is. For example, an air conditioner that requires 750 watts of electricity to provide 6,000 Btu of cooling will be less efficient than one that can provide the same amount of cooling for only 500 watts. The most common ratings applied to energy systems are EER and SEER for most central cooling systems; COP for some heat pumps and chillers; HSPF for heat pumps in their heating modes; and AFUE for gas furnaces and boilers.

For more detailed explanations of the efficiency terms mentioned above, select any of the underlined topics below.

Glossary of Efficiency Terms

AFUE (annual fuel utilization efficiency):an efficiency rating that measures the efficiency with which gas and other fossil-fuel-burning furnaces and boilers use their primary fuel source over an entire heating season. It does not take into account the efficiency with which any component of the system, such as a furnace fan motor, uses electricity. AFUE is expressed as a percentage that indicates the average number of Btu worth of heating comfort provided by each Btu worth of gas (or other fossil fuel) consumed by the system. For instance, a gas furnace with an AFUE of 80% would provide 0.8 Btu of heat for every Btu of natural gas it burned.

When comparing efficiencies of various gas furnaces, it is important to consider the AFUE, not the steady state efficiency. Steady state refers to the efficiency of the unit when the system is running continuously, without cycling on and off. Since cycling is natural for the system over the course of the heating season, steady state doesn’t give a true measurement of the system’s seasonal efficiency. For instance, gas furnaces with pilot lights have steady-state efficiencies of 78% to 80%, but seasonal efficiencies B AFUEs B closer to 65%.

Virtually all gas forced-air furnaces installed in this area from the 1950s through the early 1980s had AFUEs of around 65%. Today, federal law requires most gas furnaces manufactured and sold in the U.S. to have minimum AFUEs of 78%. (Mobile home furnaces and units with capacities under 45,000 Btu are permitted somewhat lower AFUEs.) Gas furnaces and boilers now on the market have AFUEs as high as 97%

Air infiltration: the introduction, usually unintentional, of unconditioned outdoor air into a mechanically heated and/or cooled building. Air infiltration can occur through any opening in the home’s structure, including seams where walls meet other walls, window or door frames, or chimneys; holes where wires or pipes penetrate walls, floors or ceilings/roofs; and between the loose-fitting meeting rails of double-hung windows or a door door bottom and door threshold. It is one of the major cause of unwanted heat gain and loss and personal discomfort in buildings.

Btu (British thermal unit): a measurement of the energy in heat. It takes one Btu of heat to warm one pound of water by 1° Fahrenheit. Btu can be used either to define an air conditioner’s cooling capacity (i.e., the number of Btu of heat that can be removed by the system) or a furnace’s heating capacity (i.e., the number of Btu of heat that can be supplied by the system).

Caulk: a substance used to seal air infiltration points between two immovable objects, such as where exterior or interior wall surfaces meet window or door frames and at corners formed by siding. Most caulks come in tubes and are applied with the use of a special caulk “gun.”

Compact fluorescent lamps (CFLs): a light “bulb” using fluorescent technology but designed to be used on many of the same fixtures traditionally used by standard incandescent “A” bulbs. They incorporate a small-diameter looped or swirled tube that is attached to a screw-in base. CFLs provide light levels comparable to 20- to 150-watt incandescent bulbs for 70% to 75% less energy. They also last 10 to 13 times longer than equivalent incandescent bulbs.

Conduction: the transfer of heat through solid objects such as glass, dry wall, brick and other building materials. The greater the difference between the outdoor and indoor temperatures, the faster conduction can occur and the more home a building can gain or lose.

Convection: the transfer of heat to or from a solid surface via a gas or liquid current. Where home heat loss and gain are concerned, heat convection is caused by air (gas) currents that carry heat from your body, furniture, interior walls and other warm objects to windows, floors, ceilings, exterior walls and other cool surfaces.

COP(coefficient of performance): a measurement of a heat pump’s efficiency (in the heating mode) at a specific outdoor temperature – usually 47°F. A COP of 1 indicates that for each unit of energy being used, an equal amount of energy, in the form of heat) is being provided by the system. A heat pump with a COP of 3 would provide three times as much energy in heat as it consumes in electricity at an outdoor temperature of 47°F. COP is also sometimes used to measure the single temperature cooling efficiency of chillers.

This formula is stated:

For instance, let’s assume a heat pump uses 4000 watts of electricity to produce 42,000 Btu per hour (Btu/hr) of heat when it is 47°F outside. To determine its COP, you would first convert the 4000 watts of electrical consumption into its Btu/hr equivalent by multiplying 4000 times 3.413 ( the number of Btu in one watt-hour of electricity). Then you would pide your answer — 13,648 Btu/hr — into the 42,000 Btu/hr heat output. This would show your heat pump to have a 47°F COP of 3.08. This means that, for every Btu of electricity the system uses, it will produce a little more than three Btu of heat when the outdoor temperature is 47°F.

The second formula is most frequently used to determine chiller efficiency. Using this calculation method, you would pide 3.516 by the number of kilowatts (kW) per ton used by the system. This formula is stated:

For example, a chiller that consumes 0.8 kW per ton of capacity would have a COP of 4.4 (3.516 pided by 0.8). On the other hand, the COP of a new, more efficient chiller, using as little as 0.5 kW per ton, would be greater than 7 (3.516 pided by 0.5).

Daylighting: the technique of using natural light from windows, skylights and other openings to supplement or replace a building’s artificial lighting system. When applied properly, daylighting can reduce a facility’s lighting costs. When applied improperly, however, it can not only lead to inappropriate light levels but can also raise the building’s cooling costs by introducing high levels of solar heat into the interior of the building.

Dedicated fixture: a lighting apparatus that is designed specifically for use with a particular type of lamp (bulb). For example, the increasing popularity of CFLshas led to the development of a growing number of fixtures – including torchieres, table lamps, ceiling drums, and recessed canisters – dedicated solely for use with compact fluorescents.

EER (energy efficiency ratio): a measurement of the energy required by a cooling system as it attempts to maintain indoor comfort at a specific outdoor temperature – usually 95°F. The term EER is most commonly used when referring to window air conditioners and geothermal heat pumps. EER equals the number of Btu per hour worth of cooling provided at the specified outdoor temperature pided by the number of watts used to provide that level of cooling.

The formula for calculating EER is:

For instance, if you have a window air conditioner that draws 1500 watts of electricity to produce 12,000 Btu per hour of cooling when the outdoor temperature is 95°, it would have an EER of 8.0 (12,000 pided by 1500). A unit drawing 1200 watts to produce the same amount of cooling would have an EER of 10 and would be more energy efficient.

Using this same example, you can see how efficiency can affect a system’s operating economy. First, you’ll need to determine the total amount of electricity — measured in kilowatt-hours— the unit will consume over a period of time. (A kilowatt-hour is defined as 1,000 watts used for one hour. This is the measure by which your monthly utility bills are calculated.) To do this, let’s assume you operate your 8 EER window air conditioner — drawing 1500 watts at any given moment — for an average of 12 hours every day during the summer. At this rate, it will use 18,000 watt-hours, or 18 kilowatt-hours (kWh) each day, leading to a total consumption of 540 kWh over the course of a 30-day month. At a summer electric rate of 6.34¢ per kWh, it would cost you $34.24 to operate that window air conditioner each month. At the same time, a 1200-watt, 10 EER system, consuming 14.4 kilowatt-hours per day and 432 kWh per month, would cost you $27.39, a 20% savings over the less efficient model.

Efficiency: the degree to which a certain action or level of work can be effectively produced for the least expenditure of effort or fuel. For instance, a light bulb that uses 15 watts of electricity to produce 900 lumens of light would operate with much greater efficiency than one that required 60 watts to produce the same light level.

HSPF (heating seasonal performance factor): a measurement of an all-electric air-to-air heat pump’s efficiency (in the heating mode) over an entire season. HSPF is calculated by piding the total number of Btus of heating provided over the entire season by the total number of watt-hours required to operate the system over the season.

The formula is written:

Most heat pumps installed in Springfield today have HSPFs in the 7.0 to 8.0 range, meaning they operate with seasonal efficiencies of anywhere from 205% to 234%. (To convert the HSPF number into a percentage, you just pide the HSPF by 3.414, the number of Btu in one watt-hour of electricity.) That means that, for every Btu-worth of energy they use over the entire heating season, these systems will put out anywhere from 2.05 to 2.34 Btu of heat. Compare this to electric furnaces, which have nominal efficiencies of 100% (for each Btu worth of electricity, they put out one Btu of heat), or new gas furnaces, which have efficiency ratings of about 80% to 97% (for each Btu worth of gas, they put out 0.8 to 0.97 Btu of heat).

NOTE:When comparing energy systems that use different primary fuel sources with different costs per Btu, it is important that you understand that higher operating efficiency is not necessarily equivalent to better operating economy. Although an electric heat pump might work with greater efficiency than a gas furnace, it won’t necessarily be more economical to run due to the pricing difference between the two fuel sources.

Insulation: a product that inhibits conductive and convective heat transfer. Some materials are naturally better insulators than others because they contain more “dead air” pockets. These pockets of trapped gas help to slow the movement of heat. However, if processed properly, virtually any product, including glass, cotton, paper, and plastic, can be used to make insulation.

Internal Heat Gain: the accumulation of heat produced by a building’s energy systems and appliances and occupants. Depending on the number of occupants and the type and number of energy systems used during the day, it’s not unusual for internal heat gain to account for 20% of a home’s total summer cooling load.

Kilowatt (kW): 1000 watts.

Kilowatt-hour (kWh): 1000 watts used for one hour – or any combination of energy multiplied by time that is equivalent to that rate of electrical consumption, such as one watt used for 1000 hours, 10 watts used for 100 hours, or 50 watts used for 20 hours. For example, a 100-watt light bulb left on for five hours each day would consume one kWh every two days. Kilowatt-hour is the primary measure on which U.S. electric companies base most customer billing. CWLP residential customers pay an average of 5.5¢ to 6¢ per kWh of electricity used.

Low-e: refers to a material designed to reduce the amount of radiant heat that can be transferred through glass or other translucent window coverings. Low-e (which stands for low-emissivity) coatings or films have the ability to re-radiate a high percentage of heat back toward its source. In summer low-e windows can be effective in reducing the amount of solar heat that can enter a house, and in winter they can reduce the amount of furnace-generated heat that can be lost to the outdoors.

Lumen: a unit of light given off by a light source. Lumen is the measurement used to compare the levels of illumination provided by different light sources.

Payback period: the amount of time it takes to achieve a full return on an investment. For instance, if a high-efficiency air conditioner would cost you $300 more to purchase than a lower-efficiency model but would save you $100 a year in operating costs, your payback period on the extra $300 investment would be three years.

Radiation: a method of heat transfer in which heat is transmitted from surface to surface via infrared waves. Radiant heat warms the surfaces it touches without increasing the temperature of the air through which it travels. All warm bodies radiate infrared energy.

Return on investment (ROI): the annual rate at which an investment earns income. It is calculated by piding the annual earnings by the investment. For instances, a bank savings account paying $3 per year per $100 investment has an ROI of 3% ($3 / $100). An efficiency investment’s ROI comes not from money paid to you, but rather from money saved by you on your energy bills.

R-value:a measurement of a material’s ability to resist heat transfer. Insulation products are rated according to the R-value. The higher its R-value, the greater the product’s ability to resist heat flow will be.

Some materials are more resistant to heat transfer than others, giving them higher R-values. One of the best ways to enhance the product’s R-value is to increase the amount of gas (including air) inside or immediately surrounding it. For instance, the glass of a single-pane window has virtually no R-value, but the thin film of air that normally exists on either side of the glass gives the window an R-value of about 0.83. Adding a second pane of glass and sealing the space between the panes will increase the thickness of one of the insulating gas layers, thereby more than doubling the window’s R-value.

Another example of how the presence of dead-air spaces affect a product’s R-value can be seen with wood. Hard woods, like oak, typically have an insulating value of R-1 per inch of thickness. However, softer woods, such as pine, might have R-values twice as high due to their greater number of air-filled pores.

Products developed especially for the purpose of impeding unwanted heat transfer are called insulation. Insulation can be made of a variety of materials, including old newspapers and wood fibers, glass fibers, and synthetic foams. It can also come in a variety of configurations, including soft blankets, rigid boards, or fluffy granular loose-fill, but what they all have in common, is their abundance of air-filled pores or pockets.

The actual R-value of insulation products can vary greatly, depending on their composition and form. The least resistant and least common are perlite and vermiculite loose-fills, at R-2.2 to R-2.7 per inch of thickness; the most resistant are polyisocyanurate rigid boards, at R-7 per inch of thickness. Fiberglass blankets and cellulose loose-fills, two of the most common residential insulations have R-values of 3.1 to 3.7 per inch.

SEER (seasonal energy efficiency ratio): a measurement of how energy efficient a central cooling system can operate over the course of an entire cooling season. This term is most often applied to central air-to-air heat pumps (in the cooling mode) and air conditioners. SEER is expressed as the pidend of the number of Btu of cooling provided over the season pided by the total number of watt-hours the system consumes. Federal law requires all central split systems now made and sold in the United States to have minimum SEERs of 10. Effective January 2006, the minimum for most systems will increase to 13.

SEER is calculated based on the total amount of cooling (in Btu) the system will provide over the entire season pided by the total number of watt-hoursit will consume:

By federal law, every central split cooling system manufactured or sold in the U.S. today must have a seasonal energy efficiency ratio of at least 10.0.

Settled density: the amount (depth) of insulation remaining after it has had a chance to settle. This term is most often applied to loose-fill insulations—particularly those made of cellulose. To ensure loose-fill cellulose insulation will maintain its desired insulating value (r-value) once it has settled, you will need to install it to a depth that is 20% to 25% deeper than your settled density r-value actually calls for.

Solar Gain: heat that builds up inside a structure as a result of sunlight that enters through transparent or translucent surfaces, such as windows, and is converted to heat after striking other surfaces inside the building. In summer, solar gain can cause as much as 50% of the interior heat gain in a home.

Thermostat Setback: an intentional effort to control building energy consumption by manually or automatically controlling thermostat settings according to the amount of cooling or heat that is needed at any given time of the day or night.

U-value: the measurement of how readily heat can flow through glass, brick, drywall and other building materials. U-values, which are expressed in decimals(e.g., U-0.166), are the opposite of R-values. The higher the U-value, the less efficient the building material will be.The lower a material’s U-value, the higher its R-value will be.

To determine the R-value of a product for which the U-value is given, you first convert the U-value to its equivalent fraction and then invert it. For instance, the equivalent fraction of U-0.166 would be 166/1000 or 1/6. This inverts to 6/1 or 6, giving you an R-value of 6.

For most consumers, U-value is likely to be of concern only when shopping for new windows, where efficiency is frequently stated in terms of U-value rather than R-value.

Vapor barrier: a material designed to resist the migration of moisture through a wall or other building component. As water vapor in the air moves from a warmer to a cooler part of the building it can settle and condense on cooler building components, such as rafters, beams and walls, eventually causing those components to mildew, rust or rot. Vapor barriers, which are impermeable to water vapor migration, help to protect against this possibility. The most common vapor barriers are made of plastic, but other materials, including oil paint, can also serve the purpose.

Watt: a unit of electric power. The amount of power required by electric appliances is expressed in watts.

Watt-hour: a unit of electric energy, equal to one watt used over a period of one hour.

Heat pumps are the most efficient form of electric heating in moderate climates, providing three times more heating than the equivalent amount of energy they consume in electricity. There are three types of heat pumps: air-to-air, water source, and ground source.

They collect heat from the air, water, or ground outside your home and concentrate it for use inside. Heat pumps do double duty as a central air conditioner. They can also cool your home by collecting the heat inside your house and effectively pumping it outside. A heat pump can trim the amount of electricity you use for heating by as much as 30% to 40%.

Heat Pump Tips

• Do not set back the heat pump’s thermostat manually if it causes the electric resistance heating to come on. This type of heating, which is often used as a backup to the heat pump, is more expensive.
• Clean or change filters once a month or as needed, and maintain the system according to manufacturer’s instructions.
• $ Long-Term Savings Tip: If you use electricity to heat your home and live in a moderate climate, consider installing an energy-efficient heat pump system.

The Power is in Your Hands  a campaign to help consumers lower their energy usage

Home Energy Saver- Web-based do-it-yourself energy audit tool (Lawrence Berkely National Laboratory)

Heating and Cooling Equipment Research & Development- Oak Ridge National Laboratory

Consumer Guide to Home Energy Savings- American Council for an Energy-Efficient Economy (ACEEE)

Residential Natural Gas Prices- Energy Information Administration (EIA) - Official Energy Statistics from the U.S.Government

Residential Electricity Prices- Energy Information Administration (EIA) - Official Energy Statistics from the U.S.Government

Residential Heating Oil Prices- Energy Information Administration (EIA) – Official Energy Statistics from the U.S.Government

ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping us all save money and protect the environment through energy efficient products and practices.

In 1992 the US Environmental Protection Agency (EPA) introduced ENERGY STAR as a voluntary labeling program designed to identify and promote energy-efficient products to reduce greenhouse gas emissions. Computers and monitors were the first labeled products. Through 1995, EPA expanded the label to additional office equipment products and residential heating and cooling equipment. In 1996, EPA partnered with the US Department of Energy for particular product categories. The ENERGY STAR label is now on major appliances, office equipment, lighting, home electronics, and more. EPA has also extended the label to cover new homes and commercial and industrial buildings.

Through its partnerships with more than 8,000 private and public sector organizations, ENERGY STAR delivers the technical information and tools that organizations and consumers need to choose energy-efficient solutions and best management practices. ENERGY STAR has successfully delivered energy and cost savings across the country, saving businesses, organizations, and consumers about $12 billion in 2005 alone. Over the past decade, ENERGY STAR has been a driving force behind the more widespread use of such technological innovations as LED traffic lights, efficient fluorescent lighting, power management systems for office equipment, and low standby energy use.

Some ways to save on water-heating bills require greater financial investments than others. You may wish to consider the no- or low-cost options before making large purchases. Also allow for circumstances that may be unique to your household when deciding on the appropriate options (e.g., a small-capacity washing machine could meet the needs of a one person household efficiently). Although it is not feasible to eliminate water heating in your home, it is possible to substantially reduce water-heating costs without sacrificing comfort and convenience.

Figuring out how much you spend to heat your water

The next time you pay your utility bill, try one simple calculation. Divide the total amount by seven. The result is the amount you spend to heat your water. (If you receive separate utility bills for gas and electricity, use the gas bill for this calculation if you have a gas water heater; use the electric bill if you have an electric water heater.)

Of course, you may think this cost is a small price to pay for the convenience of a hot shower. But during the course of a year, this cost adds up. And when you consider that 95 million households in this country pay the same percentage, it is easy to see how much money—and energy—is used to heat water.

Several measures can help you decrease water-heating costs in your home. Some specific actions include reducing the amount of hot water used, making your water-heating system more energy efficient, and using off-peak power to heat water.

Reducing the amount of hot water used

Generally, four destination points in the home are recognized as end uses for hot water: faucets, showers, dishwashers, and washing machines. Now, you do not have to take cold showers, dine on dirty dishes, or wear dirty clothes to reduce your hotwater consumption. Less radical measures are available that will be virtually unnoticeable once you apply them.

Faucets and Showers

Simply repairing leaks in faucets and showers can save hot water. A leak of one drip per second can cost $1 per month, yet could be repaired in a few minutes for less than that. And some apparently insignificant steps, when practiced routinely at your household, could have significant results. For example, turning the hot-water faucet off while shaving or brushing your teeth, as opposed to letting the water run, can also reduce water-heating costs. Another option is limiting the amount of time you spend in the shower. Other actions may require a small investment of time and money. Installing low-flow showerheads and faucet aerators can save significant amounts of hot water. Low-flow showerheads can reduce hot water consumption for bathing by 30%, yet still provide a strong, invigorating spray.

Faucet aerators, when applied in commercial and multifamily buildings where water is constantly circulated, can also reduce water-heating energy consumption. Older showerheads deliver 4 to 5 gallons (15.1 to 18.9 liters) of water per minute. Although a low-flow showerhead delivers slightly less water than a standard showerhead, the spray can still be invigorating.

[FS 204 January 1995] sets maximum water flow rates at 2.5 gallons (9.5 liters) per minute at a standard residential water pressure of 80 pounds per square inch (552 kilopascals).

A quick test can help you determine if your shower is a good candidate for a showerhead replacement: Turn on the shower to the normal pressure you use, hold a bucket that has been marked in gallon increments under the spray, and time how many seconds it takes to fill the bucket to the 1-gallon (3.8-liter) mark. If it takes less than 20 seconds, you could benefit from a low-flow showerhead. A top quality, low-flow showerhead will cost $10 to $20 and pay for itself in energy saved within 4 months. Lower quality showerheads may simply restrict water flow, which often results in poor performance.

Because of the different uses of bathroom and kitchen faucets, you may need to have different water flow rates in each location. For bathroom faucets, aerators that deliver 0.5 to 1 gallon (1.9 to 3.8 liters) of water per minute may be sufficient. Kitchen faucets may require a higher flow rate of 2 to 4 gallons (7.6 to 15.1 liters) per minute if you regularly fill the sink for washing dishes. On the other hand, if you tend to let the water run when washing dishes, the lower flow rate of 0.5 to 1 gallon per minute may be more appropriate. Some aerators come with shut-off valves that allow you to stop the flow of water without affecting the temperature.

Automatic Dishwashers

A relatively common assumption is that washing dishes by hand saves hot water. However, washing dishes by hand several times a day could be more expensive than operating some automatic dishwashers. If properly used, an efficient dishwasher can consume less energy than washing dishes by hand, particularly when you only operate the dishwasher with full loads.

The biggest cost of operating a dishwasher comes from the energy required to heat the water before it ever makes it to the machine. Heating water for an automatic dishwasher can represent about 80% of the energy required to run this appliance. Average dishwashers use 8 to 14 gallons (30.3 to 53 liters) of water for a complete wash cycle and require a water temperature of 140°F (60°C) for optimum cleaning.

But, setting your water heater so high could result in excessive standby heat loss. This type of heat loss occurs because water is constantly heated in the storage tank, even when no hot water is used. Furthermore, a water heater temperature of 120°F (48.9°C) is sufficient for other uses of hot water in the home. The question, then, is must you give up effective cleaning for hotwater energy savings? The answer is no.

A “booster” heater can increase the temperature of the water entering the dishwasher to the 140°F recommended for cleaning. Some dishwashers have built-in boosters that will automatically raise the water temperature, while others require manual selection before the wash cycle begins. A booster heater can add about $30 to the cost of a new dishwasher but should pay for itself in water-heating energy savings in about 1 year if you also lower your water heater temperature. Reducing the water heater temperature is not advisable, however, if your dishwasher does not have a booster heater.

Another feature that reduces hot-water use in dishwashers is the availability of cycle selections. Shorter cycles require less water, thereby reducing the energy cost. The most efficient dishwasher currently on the market can cost half as much to operate as the most inefficient model.

If you are planning to purchase a new dishwasher, check the EnergyGuide labels and compare the approximate yearly energy costs among brands. Dishwashers fall into one of two categories—compact capacity or standard capacity. Although compact capacity dishwashers may appear to be more energy efficient, they hold fewer dishes and may force you to use the appliance more frequently than you would use a standard-capacity model. In this case, your energy costs could be higher than with the standard-capacity dishwasher.

Turning the hot-water faucet off while shaving or brushing your teeth, as opposed to letting the water run, can reduce water-heating costs. An efficient automatic dishwasher can consume less energy than washing dishes by hand, particularly when you only operate the dishwasher with full loads.

Washing Machines

Like dishwashers, much of the cost—up to 90%—of operating washing machines is associated with the energy needed to heat the water. Unlike dishwashers, washing machines do not require a minimum temperature for optimum cleaning. Either cold or warm water can be used for washing most laundry loads; cold water is always sufficient for rinsing. Make sure you follow the cold-water washing instructions for your particular laundry detergent. Washing only full loads is another good rule of thumb for reducing hot-water consumption in clothes washers. As you would for dishwashers, consult the EnergyGuide labels when shopping for a new washing machine. Inefficient washing machines can cost three times as much to operate as efficient machines. Select a machine that allows you to adjust the water temperature and water levels for the size of the load. Also, front-loading machines use less water and, consequently, less energy than top loaders.

However, in this country, front loaders are not as widely available as top loaders. Keep in mind that the capacity of front loaders may be smaller than that of most top-loading machines.

Smaller capacity washing machines often have better EnergyGuide ratings. However, a reduced capacity might cause you to increase the number of loads you wash and possibly increase your energy costs.