Hunt for air leaks. A total home energy audit includes this service, but it’s pricey—around $350. Instead, try the Black & Decker Thermal Leak Detector ($50, amazon.com), which identifies drafty areas in a home. Once you seal the problem spots, you could save up to 20 percent on energy costs.
Don’t overinsulate. Depending on where you live, you may not need insulation with the highest R-value (a measure of its ability to resist heat flow). For example, outfitting an 800-square-foot attic in Florida with high-quality R-60 fiberglass loose fill would cost about $2,480, whereas using R-30, which is sufficient in warmer climates, would run only about $1,120. To find out how much insulation you need, go to energystar.gov.
Change your filter only when it’s dirty. Install a whistle on your furnace ($1.70, amconservationgroup.com) that alerts you when your filter is partially clogged and will soon need to be replaced, says Ed Pollock, a spokesperson for the U.S. Department of Energy.