Acid Rain

Rain that has become acidic due to the emission of sulfur dioxide and nitrogen oxides. To learn more, see the U.S. Environmental Protection Agency's Acid Rain Home Page.

Air Leakage Rating

The air leakage rating is a measure of how much air leaks through the crack between the window sash and frame. The rating reflects the leakage from a window exposed to a 25-mile-per-hour wind, and is measured in cubic feet per minute per linear foot of sash crack. The rating is determined according to ASTM E-283, "Standard Test Methods for Rate of Air Leakage Through Exterior Windows, Curtain Walls and Doors."

Annual Fuel Utilization Efficiency (AFUE)

An indication of how well a furnace converts energy into usable heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

Blower Doors

Energy contractors use blower doors to see how much air leaks through windows, doors, and other places in your house. The blower door is a large board that blocks the front door of your house. A powerful fan installed in the door draws the air out of your house and causes a strong draft inside whereever the air is leaking in. This can help the contractor locate the air leaks, and gives a good overall indication of how "leaky" your house is. To learn more, visit the following sites:

British thermal unit (Btu)

One British thermal unit, or Btu, is roughly equivalent to burning one kitchen match. That may not sound like much, but a typical home consumes about 100 million Btus per year. Approximately one-half fo the total is used for space heating.

Cold-Weather Ballast

Compact fluorescent light bulbs require a ballast to regulate the voltage of the electricity that is applied to the gas inside the lamp. Below-freezing weather can adversely affect the electronic components in these ballasts, causing most compact fluorescent bulbs to appear dim in cold weather. Cold-weather ballasts compensate for this problem and keep the bulb glowing brightly, even in weather as cold as -10°F (-23°C).

Electric Resistance Heating

A type of heating system that generates heat by passing current through a conductor, causing it to heat up. These systems usually use baseboard heaters, often with individual controls. They are inefficient and are best used as a backup to more efficient options, such as solar heating or a heat pump. For more information, see "Saving Energy with Electric Resistance Heating," provided by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Electro-Luminescent Night Lights

Electro-luminescent materials glow when a small electric charge is applied to them. Night lights that use these materials produce enough light to help you find your way in an otherwise dark room, but use only a few pennies worth of electricity each year. These night lights are also safer, as they are cool to the touch.

Electronic Ballasts

An electronic device that regulates the voltage of fluorescent lamps. Compared to older magnetic ballasts, electronic ballasts use less electricity and are not prone to the flickering and humming effects sometimes associated with magnetic ballasts.

Energy Efficiency Ratio (EER)

The ratio of the cooling capacity of the air conditioner, in Btu per hour, to the total electrical input in watts under test conditions specified by the Air-Conditioning and Refrigeration Institute.

Exterior Sheathing

The first covering of boards or of waterproof material on the outside wall of a frame house or timber roof. Taping the joints in this layer of material will help prevent air inleakage. To learn more about this, see the fact sheet on "Vapor Diffusion and Air Retarders," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Fluorescent Lamps

Fluorescent lamps produce light by passing electricity through a gas, causing it to glow. The gas produces ultraviolet light; a phosphor coating on the inside of the lamp absorbs the ultraviolet light and produces visible light. Fluorescent lamps produce much less heat than incandescent lamps and are more energy efficient. Linear fluorescent lamps are used in long narrow fixtures designed for such lamps. Compact fluorescent light bulbs have been designed to replace incandescent light bulbs in table lamps, floodlights, and other fixtures. To learn more about lighting, see the Buying Lighting section of the Office of Building Technology, State and Community Programs web site, or see the factsheet, "Compact Fluorescent Lamps," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Global Warming

Global warming is the gradual increase in global temperatures caused by the emission of gases that trap the sun's heat in the Earth's atmosphere. Gases that contribute to global warming include carbon dioxide, methane, nitrous oxides, chlorofluorocarbons (CFCs), and halocarbons (the replacements for CFCs). The carbon dioxide emissions are primarily caused by the use of fossil fuels for energy. For more information, visit the U.S. Environmental Protection Agency's Global Warming Web site, the Environmental Defense Fund's Global Warming Web site, or visit ABC News' Solutions to Global Warming Web site.

Heat Exchanger

A device used to transfer hear from a fluid (liquid or gas) to another fluid, where the two fluids are physically separated (usually by metal tubing). Household examples of heat exchangers are heating radiators and the coils on your refrigerator and room air conditioner.

Heat Pump

A device that extracts available heat from one area (the heat source) and transfers it to another (the heat sink) to either heat or cool an interior space. For instance, in heating climates, during the winter the heat pump extracts heat from the air outside and transfers it to the inside of the house to heat the house. In cooling climates, during the summer the heat pump extracts heat from the air inside the house, cooling it, and transfers it outside. Heat pumps work very much like your refrigerator: heat is released from the back of your refrigerator as it grows cooler inside. This is exactly like cooling your house during the summer.

Heat pumps can be very energy efficient, because instead of actually generating heat like a furnace, they just draw heat from the outside. But because the efficiency drops as the air outside gets very cold, many builders are turning instead to ground-loop or geothermal heat pumps. These heat pumps operate more efficiently than the standard air-source heat pumps, because the ground doesn't get as cold as the outside air (and during the summer, it doesn't heat up as much). To learn more about air-source heat pumps, see the "Heat Pump" section of the Energy Efficient Appliances web site, provided by the U.S. Department of Energy's Office of Codes and Standards. If you're planning on buying a new heating or cooling system, visit the U.S. Environmental Protection Agency's Energy Star®-Labeled Heating and Cooling Products.

Heat Transfer

The flow of heat from one substance to another, for instance, the flow of heat from your water heating element to the water that surrounds it.

Heating Seasonal Performance Factor (HSPF)

The total heating output of a heat pump in in Btu during its normal usage period for heating divided by the total electrical energy input in watt-hours during the same period.

High-Pressure Sodium Lighting

High-pressure sodium lamps are a form of high-intensity discharge (HID) lamps, which use an electric arc to produce intense light. High-pressure sodium lamps are energy-efficient, reliable, and have long service lives. For more information, see the factsheet "Energy Efficient Lighting," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Housewrap

Housewrap is a sheet of plastic, often fiber-reinforced, that is used to reduce air leakage in new homes. These sheets are wrapped around the outside of a house during construction. Builders must seal the housewrap at all joints and seams to create a truly continuous, effective air retarder. To learn more about this, see the fact sheet on "Vapor Diffusion and Air Retarders," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Incandescent Light Bulbs

Incandescent light bulbs produce light by passing electricity through a thin filament, which becomes hot and glows brightly. Incandescent light bulbs are less energy-efficient than fluorescent lamps, because much of the electrical energy is converted to heat instead of light. The heat produced by these bulbs not only wastes energy, but can also make a building's air conditioning system work harder and consume more energy. To learn more about lighting, see the Buying Lighting section of the Office of Building Technology, State and Community Programs web site.

Infrared Cameras

Energy contractors use infrared cameras to look at the heat leaking into or out of your house. The infrared camera "sees" the heat and can show "hot spots" where a lot of heat is being lost. This helps to identify the places where your home's energy efficiency can be improved. For more information, see the fact sheet on "Thermography," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Internal Heating Elements

A feature in dishwashers that allows the machine to heat your hot water to a higher temperature. Although this makes your dishwasher use more energy, it also allows you to reduce your hot water heater's temperature to 120EF, which will save energy. For more information, see the "Dishwashers" section of the Energy Efficient Appliances web site, provided by the U.S. Department of Energy's Office of Codes and Standards.

Kilowatt-Hour (kWh)

One kilowatt-hour (kWh) is equal to using 1000 watts of electricity for one hour. This is equal to burning a 50-watt light bulb for 20 hours, or roughly equivalent to cooking a pot of rice for an hour. Your utility bill usually shows what you are charged for the kilowatt-hours you use. The average residential rate is 8.3 cents per kWh. A typical U.S. household consumes about 10,000 kWh per year, costing an average of $830 annually.

Low Emissivity (low-e) Coatings

Emissivity is a measure of how much heat is emitted from an object by radiation. Heat is transferred to and from objects through three processes: conduction, convection, and radiation. For instance, on a hot night, heat will be conducted through a window from the outside, causing the inside pane to become warm. Convection, or natural circulation, of the air in the room past the window will transfer some of that heat into the room. But the window will also radiate heat as infrared waves, which will warm objects throughout the room. This radiative heating is why you can feel the heat of a red-hot piece of metal (for instance, a heating element on an electric stove) from several feet away.

Low-emissivity, or low-e, coatings are put on window panes to reduce the amount of heat they give off through radiation. In hot climates, where the outside of the window will typically be hotter than the inside, low-e coatings work best on the interior of the outside window pane. In cold climates, where the inside of the window is typically hotter than the outside, the low-e coatings work best on the inside window pane, on the side that faces toward the outside. To learn more about window coatings, see "Advances in Glazing Materials for Windows," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Seasonal Energy Efficiency Ratio (SEER)

he total cooling output of a central air conditioner in British thermal units during its normal usage period for cooling divided by the total electrical energy input in watt-hours during the same period. The test procedure is determined by the Air-Conditioning and Refrigeration Institute.

Solar Heat Gain Coefficient (SHGC)

The solar heat gain coefficient, also called a shading coefficient, is a measure of how well a window absorbs or reflects heat from the sun. The lower the coefficient, the better the window is at blocking the sun's heat. Windows in hot or temperate climates should have a low SHGC; south-facing windows in cold climates should have a high SHGC. The SHGC is included as part of the National Fenestration Rating Council (NFRC) Certification Label.

Spectrally Selective Coatings

A type of window glazing film that blocks the infrared portion of sunlight while admitting the visible portion. Since the infrared portion of sunlight is the main cause of solar heating, blocking out that portion allows the sun to shine in your window without causing the house to heat up. This is ideal for hot climates, but should not be used in cold climates. On windows with the National Fenestration Rating Council (NFRC) Certification Label, spectrally selective coatings would have a low solar heat gain coefficient and a high visible light transmittance. To learn more about window coatings, see "Advances in Glazing Materials for Windows," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Storm Windows

An extra pane of glass or plastic added to a window to reduce air infiltration and boost the insulation value of a window. If you are considering adding storm windows, you should compare the costs to installing new energy-efficient windows. See the "Storm Windows" fact sheet prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Surface thermometers

As the name implies, surface thermometers have a temperature probe that can be placed directly on a surface to see what temperature it is. This can help energy contractors evaluate how well heat is passing through your doors, windows, walls, floor, and ceiling. Placed on a window, for instance, it can tell you if the window is close to the room temperature (indicating that it insulates well) or closer to the outside temperature (indicating that it insulates poorly).

U-value

The U-value, also called the U-factor, is a measure of how well heat flows through an object (thermal conductivity). It is also referred to as the heat transfer coefficient or the coefficient of heat transmission. The U-value is measured by how much heat (Btu) flows through a certain area (a square foot) each hour for a certain temperature difference (°F), so it is measured in Btu/ft2-hr-°F. The U-value is the reciprocal of the R-value: the lower the U-value, the better the insulation value of the material. Many building and insulation products have their U-value indicated on their label. See, for example, the National Fenestration Rating Council (NFRC) label. NFRC also has a Certified Products Directory that lists the U-values for more than 30,500 certified products.

Vapor Barrier

Also called a vapor retarder, this is a material that retards the movement of water vapor through a building element (such as walls, floors, and ceilings) and prevents metals from corroding and insulation and structural wood from becoming damp. To learn more about vapor barriers, see the fact sheet entitled "Vapor Diffusion and Air Retarders," prepared by the U.S. Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse.

Whole-House Fan

A large fan used to ventilate your entire house. This is usually located in the highest ceiling in the house, and vents to the attic or the outside. Although whole-house fans are a good way to draw hot air from the house, you must be careful to cover and insulate them during the winter, when they often continue to draw hot air from people's houses. For more information, see the fact sheet, "Installing and Using a Whole House Fan" on the Office of Building Technology, State and Community Programs web site.

 

ENERGY STAR — ENERGY STAR is a government-backed program helping businesses and individuals protect the environment through superior energy efficiency.

ENERGY STAR Home Sealing — A process recommended by the ENERGY STAR Program for improving the envelope of a home to make it more comfortable and energy-efficient. The process includes sealing air leaks and adding insulation where cost-effective.

Air Duct — A hollow conduit or tube (square or round) that circulates air from a forced-air heating and/or cooling system to a room (supply duct) or returns air back to the main system from a room (return duct).

Air Leak — A hole, crack, or gap where air can leak in or out of a house. Air leaks can make a home feel drafty or uncomfortable and waste energy.

Gable Vent — A screened vent installed at or near the peak of a roof gable that allows warm attic air to escape.

Insulation — A material that is designed to slow down the flow of heat in or out of a building structure.

Joist — A beam used to support floors or roofs.

Kneewall — A short wall in a room with a sloped ceiling. It is usually formed when the room ceiling follows the roof line of a house.

Rafter Vent — A vent leading from the soffit into the attic through the space between the attic rafters. This vent allows air to correctly flow past insulation into the attic space.

Recessed "Can" Light — A metal light fi xture (or can) that is inset into the ceiling. These fixtures can be a big source of air leaks when installed in the upper fl oor of a home.

Ridge Vent — A screened vent installed along the top ridge of a roof that allows warm attic air to escape.

Sill Plate — A wood plank that lays flat on top of a concrete or masonry foundation or wall that supports a floor or ceiling joist.

Soffit — The underside of a building overhang, beam, or arch, especially the underside of a stair or roof overhang.

Soffit Vent — A screened vent in a house soffit that allows air to flow into the attic or the space below the roof sheathing. This helps keep the attic cool in the summer and allows moisture in the attic to evaporate.

 

 

Whole House Ventilation

Whole house ventilation using a whole house fan can substitute for an air conditioner most of the year in most climates. Whole house fans combined with ceiling fans and other circulating fans provide acceptable summer comfort for many families, even in hot weather. In addition to whole house fans, the ducts of your central heating and cooling system can be modified to provide whole house ventilation.

How Whole House Fans Work

The whole house fan pulls air in from open windows and exhausts it through the attic and roof. It provides good attic ventilation in addition to whole house ventilation. Whole house fans should provide houses with 30–60 air changes per hour (varies with climate, floor plan, etc.—check with a professional to determine what is appropriate for your home). The air-change rate you will choose depends on your climate and how much you will depend on the whole house fan for cooling.

Sizing a Whole House Fan

Whole house fans are sized in cubic feet per minute (cfm) of ventilating power. To determine the size you'll need, first calculate the volume of your house in cubic feet. To do that, multiply the square footage of the floor area you want to cool by the height from floor to ceiling. Take that volume and multiply by 30 to 60 air changes per hour (depending on the power you need). Then, divide by 60 minutes to get the cubic feet per minute of capacity your house requires.

[(Square feet______ x room height______) x 30 or 60/ 60 = cfm required _________. ]

Installing and Using a Whole House Fan

Installing a whole house fan is tricky and should be done by a professional. An experienced professional should perform your attic measurements and install your dedicated circuit wiring and, if needed, your new attic vents.

Attic ventilation will usually need to be increased to exhaust the fan's air outdoors. You'll need 2–4 times the normal area of attic vents, or about one square foot of net free area for every 750 cubic feet per minute of fan capacity. The net free area of a vent takes into account the resistance offered by its louvers and insect screens. More vent area is better for optimal whole house fan performance.

If your fan doesn't come with a tight-sealing winter cover, you should either buy one or build one. If you switch between air conditioning and cooling with a whole house fan as the summer weather changes, build a tightly sealed, hinged door for the fan opening that is easy to open and close when switching cooling methods.

Be cautious when operating these large exhaust fans. Open windows throughout the house to prevent a powerful and concentrated suction in one location. If enough ventilation isn't provided, the fans can cause a backdraft in your furnace, water heater or gas-fired dryer, pulling combustion products such as carbon monoxide into your living space.

Drawbacks of Whole House Fans

Whole house fans can be noisy, especially if improperly installed. In general, a large-capacity fan running at low speed makes less noise than a small fan operating at high speed. All whole house fans should be installed with rubber or felt gaskets to dampen noise. You can set a multi-speed fan to a lower speed when noise is a problem.

Using Your Duct System as a Whole House Fan

You may be able to use the heating and air conditioning ducts in your home as a means of whole house ventilation. This would involve installing an intake duct to pull air into an attic-mounted system that directs the air into your heating and cooling ducts. A damper would control exhaust air from your home into the attic. Check with a local professional to find out if this option is right for you.

 

Ceiling Fan Installation and Usage Tips

Ceiling fan performance and energy savings rely heavily on the proper installation and use of the ceiling fan. Here are a few tips to ensure quality and product performance.

Note: consumers should read and understand manufacturer instructions before attempting to install a ceiling fan.

Choosing the Appropriate UL-Rated Electrical Box

Make sure that you use the appropriate UL-listed metal box, marked “For Use With Ceiling Fans.” This outlet box is mounted above the ceiling and also is the point where the fan is attached. This box houses all wiring needed to operate and connect the ceiling fan. If you are replacing a ceiling fixture, most likely you will need to replace the electrical box.

Mounting the Ceiling Fan

If possible, the ceiling fan should be anchored to a ceiling joist. In the case that the joist is not located in the center of the room, a special ceiling fan mounting bracket with spiked ends should be installed between joists. Keep in mind that ceiling fans can weigh as much as 50 pounds! For tips on installing a ceiling fan, click on the file below.

Balancing a Wobbly Fan

All fan blades should be balanced prior to shipment; however, if the fan is wobbly after installation, there are ways to fix it. First, make sure that all connections are properly aligned and tightly fastened. Check the alignment of the blades by holding a yardstick vertically along the edges; you may be able to gently bend a misaligned blade holder back into proper place. If all blades are aligned, a balancing kit can then be used to pinpoint the culprit. These kits are either provided within product packaging (e.g., balancing clips and blade weights) or can be sent by the manufacturer free of charge.

Turn Off When not in the Room

Ceiling fans cool people, not rooms. If the room is unoccupied, turn off the ceiling fan to save energy.

Using the Ceiling Fan Year Round

In the summer, use the ceiling fan in the counter-clockwise direction. While standing directly under the ceiling fan you should feel a cool breeze. The airflow produced creates a wind-chill effect, making you “feel” cooler. In the winter, reverse the motor and operate the ceiling fan at low speed in the clockwise direction. This produces a gentle updraft, which forces warm air near the ceiling down into the occupied space. Remember to adjust your thermostat when using your ceiling fan — additional energy and dollar savings could be realized with this simple step!