A combination of proper insulation, energy-efficient windows and doors, daylighting, shading, and ventilation will usually keep homes cool with a low amount of energy use in all but the hottest climates.
Ventilation is the least expensive and most energy-efficient way to cool buildings. Ventilation works best when combined with methods to avoid heat buildup. In some cases, natural ventilation will suffice for cooling, although it usually needs to be supplemented with spot ventilation, ceiling fans and window fans. For large homes, homeowners might want to investigate whole house fans. Ventilated attics are about 30°F (16°C) cooler than unventilated attics. Properly sized and placed louvers and roof vents help prevent moisture buildup and overheating in attics.
Avoiding Heat Buildup
Keeping the heat outside, avoiding heat-generating activities, and using spot ventilation can help keep buildings cool during hot days.
In some parts of the United States, natural convection and cool breezes are sufficient to keep homes cool.
Ceiling Fans and Other Circulating Fans
Fans that circulate air within your home can improve your comfort level.
Window fans use relatively little electricity and provide sufficient cooling for homes in many parts of the country.
Whole House Fans
For larger homes, a whole house fan provides excellent ventilation to achieve lower indoor temperatures. For homes with ducts, an alternative approach uses those ducts to supply ventilation air throughout the home.
Two-thirds of all homes in the United States have air conditioners. Air conditioners use about 5% of all the electricity produced in the United States, at a cost of over $11 billion to homeowners. Switching to high-efficiency air conditioners and taking other actions to keep your home cool could reduce this energy use by 20%–50%.