"We hooked up a whole-house fan."
Dwight and Shannon Okahara, Santa Clarita, California

How It Works: A large fan at the center of the house pulls in cool air through open windows on lower floors, drawing warm air up and out through windows or roof vents. Whole-house fans use about one-fifth of the electricity consumed by central AC.

What These Homeowners Did: First, Dwight and Shannon did their homework. They learned that their climate—cool early in the morning and at night—is ideal for this old-fashioned fix. So last spring, Dwight installed a Master Flow fan made by of Wayne, New Jersey, in the attic floor of their 2,500-square-foot house. He cut a hole in the second-story hall ceiling and, working from the attic, mounted the fan on top of the exposed joists. Then he hard-wired the fan to a switch in a nearby bedroom and finished the hall ceiling with a louvered panel that closes automatically when the fan is off. "It was a 'measure nine times, cut once' type of job," he deadpans.

What They Learned: They can lower the indoor air temperature by 5 degrees F in an hour by running the fan full tilt. "The funny part is, it can get too cold at night," says Dwight. "I end up turning it off and getting under the comforter." It takes a little experimenting, opening some doors and windows and closing others, to direct the cool air where you want it most. Last summer they used their central AC only when the outside temperature hit 85 degrees F.

Keep in Mind: A whole-house fan doesn't dehumidify the way AC does. It works best when located in the center of the house. Some models are loud—decibel levels range from 60 to 71. The Okaharas' generates 65 decibels, about as loud as a window air conditioner. Also, since it has no filter, a whole-house fan will draw in outdoor allergens.

Payback Period: 6 to 8 months
Their Cost: $260, with DIY installation
Yearly Savings on Electricity for AC: $1,500
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