Air Conditioning Energy Efficiency Tips
How To Keep Cool When It's Hot Outside
- Close doors, windows and window coverings during the day when you’re out of the house, especially on the south side of the house. Reopen windows and coverings at night or in the morning to let in cooler air.
- Avoid producing heat inside your home when it's hot outside. Do laundry, run dishwasher, etc., in the early morning and late evening hours.
- Try cooling down with a cold shower rather than cooling the entire house.
- Consider installing an attic fan to draw hot air out of the house.
- Plant deciduous trees or install awnings to shade your home, especially on the south and west sides of your house. Before planting trees, make sure they won’t interfere with power lines once they grow to their full size. Refer to our Tree Planning and Planting Guide for more information.
- Consider installing a ceiling fan in rooms used frequently. Moving air can feel up to four degrees cooler than still air. Ceiling fans are effective in homes both with and without air conditioning. Look below for more information about ceiling fans.
- Turn the air conditioner off when you're going to be gone for an extended period.
Central Air Conditioning
- If you are experiencing problems and your air conditioner is more than 10 years old, consider buying a new one. A new efficient unit, when properly sized and installed, will cost significantly less on a monthly basis.
- Look for an air conditioner that has a Seasonal Energy Efficiency Rating (SEER) of 13 or higher and has the ENERGY STAR® label. ENERGY STAR-qualified air conditioners are 25 percent more efficient than conventional units.
- Buying the correct size unit and installing it properly is critical to efficiency and comfort. Seek sizing guidance from a local HVAC dealer, and make sure a trained professional installs the new unit.
- Consider purchasing an air conditioner with a variable speed motor, providing a more efficient system along with increased comfort and less noise.
- Try to have your new air conditioner placed in a shady spot, preferably on the north side of your home.
- Ask for an inspection of your duct system. Leaky duct systems are more common than you might realize and reduce the effectiveness of your air conditioner.
Selecting and Installing Central Air Conditioning
- Routinely check your air conditioner's air handler or furnace filter during the cooling season. Clean or replace as needed. Dirty filters block normal airflow and significantly reduce a system's efficiency.
- If you are experiencing a problem, have your air conditioner professionally serviced. Ask for a tune-up that includes a check of the refrigerant charge, cleaning of the coils and an inspection of your duct system.
Air Conditioner Maintenance
- Don’t crank the temperature down in an effort to cool your house off quickly. It will not affect the speed at which the house cools.
- Check your thermostat setting. Most people can be comfortable at 78 degrees. Remember that thermostats are not always accurate.
- Consider installing a programmable thermostat that ensures your home is cool just when you want it to be. Look for the ENERGY STAR label when shopping for programmable thermostats.
- Weather strip doors and windows to prevent losing cool air to the outside. Make sure there's sufficient insulation throughout the home to help keep cool air in.
Everyday Air Conditioner Tips
Room Air Conditioners
Selecting and Installing
- Shop for a unit with an Energy Efficiency Rating (EER) of at least 10. Better yet, buy an ENERGY STAR-qualified unit, which has a designated EER based on its cooling potential. ENERGY STAR-qualified room air conditioners use at least 10 percent less energy than current conventional models and significantly less than older models.
- Look for a unit with a filter that slides out easily for regular cleaning.
- Install the unit in a north window or shaded area for optimal operation.
- Consider a unit with controls such as a digital readout for the thermostat setting and a built-in timer, both of which can help you adjust your unit to use less energy.
- Bigger is not always better! Purchasing a unit that is too large is actually less efficient. Use this chart to determine what size you need. For room AC units, size is measured in Btu's, an indication of cooling capacity.
Area To Be Cooled (square feet)
Capacity Needed (Btu's per hour)
|100 to 150||5,000|
|150 to 250||6,000|
|250 to 300||7,000|
|300 to 350||8,000|
|350 to 400||9,000|
|400 to 450||10,000|
|450 to 550||12,000|
|500 to 700||14,000|
|700 to 1,000||18,000|
Make adjustments for the following circumstances:
- If the room is heavily shaded, reduce capacity by 10 percent.
- If the room is very sunny, increase capacity by 10 percent.
- If more than two people regularly occupy the room, add 600 Btu's per person.
- If the unit is used in a kitchen, increase capacity by 4,000 Btu's.
- Clean filter monthly when in use. Wash foam filters with soap and water and let it air dry.
- Drain and clean the drain pan on the underside of the unit every season.
Room Air Conditioner Maintenance
- Units tend to run better at 7 or 8, not at 10.
- Install a timer on the unit if you want the room cool when you get home.
Everyday Room Air Conditioner Tips
- Look for the ENERGY STAR label and save at least 10 percent in energy costs over standard ceiling fans. Savings come mostly from the lighting on the fan so, if your fan doesn't include lighting, be sure to purchase an ENERGY STAR-qualified light kit.
- For summer and winter savings, buy a reversible fan that will circulate cooler air in summer and warmer air in winter.
- Install the fan with the blades at least seven feet above the floor, one foot below the ceiling and two feet from the nearest wall.
- Consider the size of the room and the size of the blades when selecting a ceiling fan. Multiple fans may be needed in rooms longer than 18 feet.
Selecting and Installing a Ceiling Fan
- Switch the fan and light off when you leave the room. Fans don't actually cool a room -- they just cool you by circulating air.
- If your ceiling fan has a reversible motor, reverse the fan during the winter months to circulate warm air throughout the room.
Everyday Tips for Ceiling Fans
Evaporative Cooler (or Swamp Cooler)
- Select a unit that has two or three blower speeds and a thermostat that automatically turns the cooler on and off.
- Sizing an evaporative cooler is less critical than sizing an air conditioner. The suggested guideline is about 3 Industry Standard CFM per square foot of area to be cooled.
- Place your evaporative cooler in a place free of outdoor obstructions, vents or combustion appliances. Make sure it is near a water source.
Selecting and Installing an Evaporative Cooler
- Have your cooler serviced twice a year -- once before the cooling season and once during the summer.
- Remove your cooler in winter and store in a dry place. Seal and insulate the cooler opening for winter heating.
Evaporative Cooler Maintenance
- Expect outdoor air to be cooled about 15-20 degrees using an evaporative cooler. The lower the humidity, the more effective the cooling is. Cooled air from an evaporative cooler will add humidity to your home.
- Leave at least one window open while operating an evaporative cooler. The cooler air will go to the rooms with airflow to the outside, so open doors and windows accordingly.
- During moderate temperatures (less than 85 degrees), use just the cooler fan to draw cooler outdoor air into the home without using the water cooler to cool the air.
- Expect to use about one third of the electricity needed to operate an air conditioner of similar capacity. At the same time, however, your cooler will use anywhere from 3 to 15 gallons of water per day.