Choose the right air conditioner.
When buying air conditioners, choose the smallest ENERGY STAR qualified unit appropriate for the size of the room you’re cooling. Too big a model not only costs more to operate but also can make a room uncomfortably clammy because oversized equipment can’t remove humidity as effectively.
Know when to turn it off.
Take advantage of those rare times when it’s cooler outside and open your windows instead of using air conditioning. Use a window fan, blowing toward the outside, to pull cool air in through other windows and to push hot air out. When it’s warmer outside than inside, close your windows and then draw window coverings against direct sunlight to delay using your air conditioning for as long as possible.
Delay heat-producting tasks.
On hot days, it's best to minimize activities that generate a lot of heat, such as running a computer or dishwasher, doing laundry, and using hot devices such as curling irons or hair dryers. Even stereos and televisions will add some heat to your home. Also keep this in mind while cooking - avoid using the oven, and instead cook on the stove, use a microwave oven, or grill outside.
Keep your cool.
A typical house has many places where air can move between living spaces and the attic, and between the basement and outdoors. The result is treated air being lost to the outdoors - and higher cooling bills. The solution is to seal gaps and then put in sufficient, well-installed insulation. The most effective, energy-saving solution is to hire a professional.
Use your ceiling fan.
In the summer, set your ceiling fan in the counterclockwise direction. While standing directly underneath it, you should feel a cool breeze. If you use air conditioning, a ceiling fan will allow you to raise the thermostat setting about 4°F with no reduction in comfort.
Use your bath fan.
Do you have mildew on bathroom ceilings? This is a sign of insufficient ventilation. If you have a bath fan, use it. If you need a fan, look for an ENERGY STAR® qualified model. These fans are very quiet and use little electricity. Be sure to vent bath fans to the outdoors, or you’ll risk moving your mildew problem to another part of the house or attic.
Dry clothes faster.
Clear lint from your clothes-dryer exhaust hose. Have a flexible hose? Replace it with smooth metal ducting to improve air flow, dry clothes faster, and reduce drying energy use.
Don’t make your fridge work so hard.
Clean dust from under your refrigerator, the front vent at the base, and any exposed coils at the back. Another tip: Make sure products aren’t blocking the fan vents inside the fridge and freezer.
Clear the air.
Dust bathroom vent fan covers as well as the ceiling fan blades (change the direction to counter clockwise while you are dusting) in other rooms in your home. Clean dust and grease from the kitchen stove hood and exhaust fan.
Plug your home electronics into an advanced power strip.
While you’re dusting your TV, computer, gaming equipment, and other home electronics, take a look at how they’re plugged in. You can stop overpaying to power these big energy users (many draw electricity even when off) by plugging them into an advanced power strip, which automatically cuts electricity to any idle equipment you choose.
Keep bulbs and fixtures clean.
Dirt will absorb the light and reduce the efficiency. Another tip: Replace incandescent light bulbs with LEDs and use up to 90% less energy.
Take a look at any accessible exterior vents, such as for the clothes dryer, central-heating system, water heater, kitchen-fan exhaust, or bath-fan exhaust. Clear them of any blockage or buildup of dust, webs, leaves, and lint.
Feeling a draft?
If you have functional windows, it makes more financial sense to improve them than to replace them with energy-efficient windows. Caulk any gaps and cracks around window frames. Be sure that windows are fully shut. Put up interior window plastic, available in kits at hardware stores. If you don't have storm windows, have them made. Also, for drafty doors, use weather-stripping and door sweeps.