July 2008
How to keep your cool
These cheap chills will help you stay comfortable without having to crank up the air conditioning
Americans spend more than $22 billion a year and use a whopping 183 billion kilowatt-hours of electricity to cool their homes
with air conditioning, according to the U.S. Department of Energy. All that A/C combined with cold-season heating also makes
our collective carbon footprint grow ever larger, with the emission of about 129 million metric tons of carbon dioxide annually.
That CO2, of course, contributes to global climate change.
But you can easily limit how much you rely on A/C. Your first step is to run your air conditioner(s) less frequently. "If you're working eight hours a day, why air-condition your house while you're away?" says Christina Kielich, a spokeswoman for the DOE. You can reduce your annual energy bills by about 10 percent by turning up your programmable thermostat 10º to 15º F when you're out of the house, says the DOE. Upon returning home, Kielich says, "Pick a temperature that's comfortable and stick with it."
Remember, electricity prices tend to rise with the temperature, but you can trim your energy bills and still stay comfortable. Ways to cut down on A/C use shows you how to use less air conditioning and cool your home more effectively.
Use your A/C wisely. Installing an air conditioner in a shady spot could increase its efficiency up to 10 percent, according to the DOE. Our latest tests of window-mounted air conditioners found CR Best Buys that cost as little as $240 for a large one. Energy Star-qualified models use about 25 percent less power than ones made before late 2000. Don't lower the air conditioner's temperature when you turn it on. It won't cool the room any faster, but it will use more energy. On humid days, set the fan speed on low to remove more moisture from the air.
Delay the chores. Your dishwasher, washer, and dryer give off heat when they're in use, so run them in the early morning or late evening. Your air conditioner won't have to work as hard to offset the heat produced by the appliances. Other benefits: Running those appliances during off-peak hours reduces the stress on the power grid, helping to prevent brownouts. You might also pay less for the electricity if your utility charges less per kilowatt-hour during nonpeak hours.
Change the lightbulbs. Much of the energy used by incandescent bulbs is emitted as heat. During the day, turn off lights that are unnecessary. Also consider replacing your incandescent bulbs with compact fluorescent lightbulbs, or CFLs. Energy Star-qualified CFLs use about 75 percent less energy and give off 75 percent less heat to produce the same amount of light as standard incandescent bulbs. Replacing a 60-watt incandescent bulb with a 15-watt CFL can save you up to $41 over the life of the bulb.
Although all the CFLs we tested last much longer than regular bulbs, the Feit Ecobulb Plus ESL13T/Eco, GE 8,000 Hour Long Life 41525, and N:Vision 423-599 lasted longest. (Note that CFLs contain small amounts of mercury. Go to www.epa.gov/bulbrecycling for recycling programs in your area.)
Make some shade. Awnings, blinds, drapes and shades keep sunlight from entering your home, so install them on windows, skylights, and doors that get a lot of sun. During the day, close the blinds, drapes and shades and roll out the awnings to filter the sun, especially for west-facing windows in the afternoon. All can help keep the room's temperature from rising.
Use fans. When the outside air is cooler than that inside your home, fans, including ceiling fans, can come in handy. Fans cost little to run, and they create a breeze that can help you feel up to 7 degrees cooler. (Our tests of ceiling fans found that price had little to do with performance.)
Vent fans draw in the cool air and exhaust the hot air, and window fans are inexpensive to operate and easy to install. To boost the chimney effect, in which warm air rises and vents naturally, place one blowing in on the ground floor, and another one blowing out on the floor above.
To keep your air conditioner from fighting heat from the attic, install an attic fan controlled by a thermostat; it will turn on automatically when the attic temperature reaches a certain point.
A whole-house fan can do the work of an air conditioner using much less electricity. This thermostatically controlled fan turns on in the evening and off in the early morning. It exhausts hot attic air and draws in cool outside air from open windows throughout the house, lowering the temperature inside the house by 3º to 6º F at night.
Plant trees. Well-placed trees and bushes can reduce the energy a home uses for cooling by up to 25 percent, according to the DOE. Deciduous trees (those that drop their leaves in fall) help the most by blocking the summer sun, yet they allow the winter sun to warm your home. Evergreen trees and shrubs offer year-round shade and block winds, which reduces heating costs.
Plant trees on the northeast-southeast and northwest-southwest sides of your home; do not plant directly to the south, unless you live in an area where it is always hot. Ideally, plant at a distance from the house that is equal to two to five times the height of the mature trees.
To increase the efficiency of your air-conditioning unit by up to 10 percent, plant trees and shrubs to shade the outside unit; place them at least 18 inches away so they don't block the vents on the compressor. For more tips on ways to use landscaping to increase the energy efficiency of your home, see the DOE's landscaping advice.
"Summerize" your home. Adding insulation and sealing air leaks help keep you comfortable year-round and can also lower your energy bills by hundreds of dollars a year. Start by insulating the attic or adding to the insulation already there, then insulate ducts in unconditioned space.
Reconsider the roofing. More than 90 percent of the roofs in this country are dark; on a hot, sunny day, dark-colored roofs can heat up to 150º to 190º F, roasting the living spaces below. Consider adding a reflective coating to a dark roof, or when it's time to replace it, choose a lighter color, which will reflect most of the heat away from your home. Homes in the north won't benefit as much as those in warmer climates, according to the National Roofing Contractors Association.
Maintain your air conditioner(s). Dirty, clogged filters increase an air conditioner's energy use. Vacuum dust and debris from inside a window unit before you install it. Clean the filter on window and central air conditioners monthly or as needed by vacuuming and washing. Some filters need to be replaced. Clear debris from outside louvers and coils. Keep plantings at least 2 feet from the condenser. For more information, read "Cool runnings."
FOR MORE INFORMATION
To learn about room air conditioners that are relatively miserly with energy, see our Ratings (available to subscribers). To buy an air conditioner that's right for your space, use our detailed sizing worksheet.
But you can easily limit how much you rely on A/C. Your first step is to run your air conditioner(s) less frequently. "If you're working eight hours a day, why air-condition your house while you're away?" says Christina Kielich, a spokeswoman for the DOE. You can reduce your annual energy bills by about 10 percent by turning up your programmable thermostat 10º to 15º F when you're out of the house, says the DOE. Upon returning home, Kielich says, "Pick a temperature that's comfortable and stick with it."
Remember, electricity prices tend to rise with the temperature, but you can trim your energy bills and still stay comfortable. Ways to cut down on A/C use shows you how to use less air conditioning and cool your home more effectively.
Use your A/C wisely. Installing an air conditioner in a shady spot could increase its efficiency up to 10 percent, according to the DOE. Our latest tests of window-mounted air conditioners found CR Best Buys that cost as little as $240 for a large one. Energy Star-qualified models use about 25 percent less power than ones made before late 2000. Don't lower the air conditioner's temperature when you turn it on. It won't cool the room any faster, but it will use more energy. On humid days, set the fan speed on low to remove more moisture from the air.
Delay the chores. Your dishwasher, washer, and dryer give off heat when they're in use, so run them in the early morning or late evening. Your air conditioner won't have to work as hard to offset the heat produced by the appliances. Other benefits: Running those appliances during off-peak hours reduces the stress on the power grid, helping to prevent brownouts. You might also pay less for the electricity if your utility charges less per kilowatt-hour during nonpeak hours.
Change the lightbulbs. Much of the energy used by incandescent bulbs is emitted as heat. During the day, turn off lights that are unnecessary. Also consider replacing your incandescent bulbs with compact fluorescent lightbulbs, or CFLs. Energy Star-qualified CFLs use about 75 percent less energy and give off 75 percent less heat to produce the same amount of light as standard incandescent bulbs. Replacing a 60-watt incandescent bulb with a 15-watt CFL can save you up to $41 over the life of the bulb.
Although all the CFLs we tested last much longer than regular bulbs, the Feit Ecobulb Plus ESL13T/Eco, GE 8,000 Hour Long Life 41525, and N:Vision 423-599 lasted longest. (Note that CFLs contain small amounts of mercury. Go to www.epa.gov/bulbrecycling for recycling programs in your area.)
Make some shade. Awnings, blinds, drapes and shades keep sunlight from entering your home, so install them on windows, skylights, and doors that get a lot of sun. During the day, close the blinds, drapes and shades and roll out the awnings to filter the sun, especially for west-facing windows in the afternoon. All can help keep the room's temperature from rising.
Use fans. When the outside air is cooler than that inside your home, fans, including ceiling fans, can come in handy. Fans cost little to run, and they create a breeze that can help you feel up to 7 degrees cooler. (Our tests of ceiling fans found that price had little to do with performance.)
Vent fans draw in the cool air and exhaust the hot air, and window fans are inexpensive to operate and easy to install. To boost the chimney effect, in which warm air rises and vents naturally, place one blowing in on the ground floor, and another one blowing out on the floor above.
To keep your air conditioner from fighting heat from the attic, install an attic fan controlled by a thermostat; it will turn on automatically when the attic temperature reaches a certain point.
A whole-house fan can do the work of an air conditioner using much less electricity. This thermostatically controlled fan turns on in the evening and off in the early morning. It exhausts hot attic air and draws in cool outside air from open windows throughout the house, lowering the temperature inside the house by 3º to 6º F at night.
Plant trees. Well-placed trees and bushes can reduce the energy a home uses for cooling by up to 25 percent, according to the DOE. Deciduous trees (those that drop their leaves in fall) help the most by blocking the summer sun, yet they allow the winter sun to warm your home. Evergreen trees and shrubs offer year-round shade and block winds, which reduces heating costs.
Plant trees on the northeast-southeast and northwest-southwest sides of your home; do not plant directly to the south, unless you live in an area where it is always hot. Ideally, plant at a distance from the house that is equal to two to five times the height of the mature trees.
To increase the efficiency of your air-conditioning unit by up to 10 percent, plant trees and shrubs to shade the outside unit; place them at least 18 inches away so they don't block the vents on the compressor. For more tips on ways to use landscaping to increase the energy efficiency of your home, see the DOE's landscaping advice.
"Summerize" your home. Adding insulation and sealing air leaks help keep you comfortable year-round and can also lower your energy bills by hundreds of dollars a year. Start by insulating the attic or adding to the insulation already there, then insulate ducts in unconditioned space.
Reconsider the roofing. More than 90 percent of the roofs in this country are dark; on a hot, sunny day, dark-colored roofs can heat up to 150º to 190º F, roasting the living spaces below. Consider adding a reflective coating to a dark roof, or when it's time to replace it, choose a lighter color, which will reflect most of the heat away from your home. Homes in the north won't benefit as much as those in warmer climates, according to the National Roofing Contractors Association.
Maintain your air conditioner(s). Dirty, clogged filters increase an air conditioner's energy use. Vacuum dust and debris from inside a window unit before you install it. Clean the filter on window and central air conditioners monthly or as needed by vacuuming and washing. Some filters need to be replaced. Clear debris from outside louvers and coils. Keep plantings at least 2 feet from the condenser. For more information, read "Cool runnings."
FOR MORE INFORMATION
To learn about room air conditioners that are relatively miserly with energy, see our Ratings (available to subscribers). To buy an air conditioner that's right for your space, use our detailed sizing worksheet.
