3 ways to cool down air-conditioning costs

Improve plantings around your house

"Most heat that accumulates inside a house comes directly from the sun shining on to the roof or through windows, and heating the house directly," says John Krigger, owner of Saturn Resource Management, which offers energy conservation training in Helena, Montana.

Planting leafy trees around the building's exterior will stop the sun from shining inside your home. "Even for the cost of going to the nursery and buying a 15- to 20-foot-tall tree, trees are still the best value," Krigger says.

If the trees or shrubs shade your air conditioner, you could increase your AC's efficiency by up to 10%, according to the U.S. Department of Energy.

Clothe your windows

Solar screens, or mesh-like window screens, intercept up to 70% of solar energy before it gets into the house, Krigger says. Window screens are particularly effective on east- and west-facing windows, according to the U.S. Department of Energy.

Window films are another option. They are transparent, metalized sheets that reflect heat before it can be transmitted through glass.

However, windows must be shut for window films to work, while solar screens do double duty, keeping sun and insects out -- even with windows open.

Flip a switch

Go ahead, get comfortable. Lower your air conditioner's thermostat setting to 78 degrees Fahrenheit when you're at home. But let that number rise to a higher temperature at night or when you're not at home. You can save 5% to 15% on your air-conditioning bills by raising the temperature setting on your thermostat when you're away and don't need cooling, according to the Department of Energy.