• Open windows and use portable or ceiling fans instead of operating your air conditioner. Even mild air movement of 1 mph can make you feel three or four degrees cooler.

• Use a fan with your window air conditioner to spread the cool air through your home.

• Use a programmable thermostat with your air conditioner to adjust the setting at night or when no one is home.

• Don't place lamps or TVs near your air conditioning thermostat. The heat from these appliances will cause the air conditioner to run longer.

• Consider installing a whole house fan or evaporative cooler (a "swamp cooler") if appropriate for your climate.

• Install white window shades, drapes, or blinds to reflect heat away from the house.

• Close curtains on south- and west-facing windows during the day.

• Install awnings on south-facing windows. Because of the angle of the sun, trees, a trellis, or a fence will best shade west-facing windows.

• Apply sun-control or other reflective films on south-facing windows.

A quick check of your air conditioner's efficiency can help you decide whether to call in a service professional. Use a household thermometer to measure the temperature of the discharge air from the register and the temperature of the return air at the return-air grill. (Keep the thermometer in place for five minutes to get a steady temperature.) The difference should be from 14 to 20 degrees, experts say. An air conditioner that's not cooling to those levels could be low on refrigerant or have leaks. A unit cooling more than 20 degrees could have a severe blockage.

You also might consider the purchase of a whole-house or attic fan, especially if you live in a multi-story home where the upper floor stays uncomfortably warm. Attics trap fierce amounts of heat; a well-placed and -sized whole-house fan pulls air through open windows on the bottom floors and exhausts it through the roof, lowering the inside temperature and reducing energy use by as much as third compared with an air conditioner. Cost is between $150 and $400.

Landscaping for a cooler house
 

• Plant trees or shrubs to shade air conditioning units, but not block the airflow. A unit operating in the shade uses less electricity.

• Grown on trellises, vines such as ivy or grapevines can shade windows or the whole side of a house.

• Avoid landscaping with lots of unshaded rock, cement, or asphalt on the south or west sides because it increases the temperature around the house and radiates heat to the house after the sun has set.

• Deciduous trees planted on the south and west sides will keep your house cool in the summer. Just three trees, properly placed around a house, can save between $100 and $250 annually in cooling and heating costs. Daytime air temperatures can be 3 degrees to 6 degrees cooler in tree-shaded neighborhoods.

• Replace incandescent bulbs with compact fluorescents.

• Air-dry dishes instead of using your dishwasher's drying cycle.

• Lower the thermostat on your hot water heater; 115° is comfortable for most uses.

• Take showers instead of baths to reduce hot water use.

• Wash only full loads of dishes and clothes.

• Caulking and weather stripping will keep cool air in during the summer.

• If you see holes or separated joints in your ducts, hire a professional to repair them.

• Add insulation around air conditioning ducts when they are located in unconditioned spaces such as attics, crawl spaces, and garages; do the same for whole-house fans where they open to the exterior or to the attic.

• Check to see that your fireplace damper is tightly closed.