Fixit: Tips on cooling off the house

Q My husband thinks you get better cooling and airflow if you leave some windows open while running the air conditioning. He leaves two windows open on the second floor of our house 2 or 3 inches. One of the windows is above the air conditioning unit. I think it is inefficient and wasteful.

A It's not wise.

"Operating the air conditioner with the window open negates the dehumidification that the AC would be providing," said Phil Smith, energy specialist with the Minnesota Department of Energy Security. "The dehumidification of air is one of the key elements to the comfort we get in air conditioning."

In the situation you describe, the open window above the compressor and coils could serve as a "short circuit," permitting heat you have just removed to simply blow back in, he added.

Close the windows when using air conditioning. But be mindful of outdoor conditions so you can turn off the AC and open your windows when the weather permits.

Other home-cooling tips from the Department of Energy Security:

• Run the dishwasher at night, turn off lights when not needed, and use bath and kitchen fans to exhaust hot, moist air from bathing and cooking to the outside.

• If you use window fans, place them on the cool side of the house, blowing inward. Fans blowing to the outside can depressurize a house, creating dangerous back-drafting problems with water heaters or other combustion appliances. Attic fans and whole house fans are not recommended for the same reason.

• Energy Star-qualified programmable thermostats save energy and money (up to 15 percent on cooling costs).

• Keep filters clean or replace them every month, and keep the outside fins on the air conditioner free of dirt and debris. Remember to have your AC tuned up regularly by a certified technician.

• Hidden gaps and cracks in a home can create as much airflow as an open window and can cause the cooling system to work harder. Sealing the home "envelope" (the outer walls, ceiling, windows and floors) can save up to 10 percent in energy costs. Pay special attention to the attic and basement.

• Tighten your ducts. It is common to find gaps between duct joints in a home, new or old. Save up to 10 percent on bills by having the ducts inspected, sealed and insulated to increase indoor air quality, maximize the movement of cooled air to all rooms and prevent loss of cooled air to areas between walls, ceilings and floors.

• Make sure new equipment is properly sized and installed. Units with too large a capacity will cost more and might actually decrease comfort. Find an experienced, licensed contractor before doing any heating or cooling overhaul. Visit www.natex.org to find a contractor whose technicians are certified by North American Technician Excellence.

• Take advantage of special offers. Many contractors, utility companies, retailers and manufacturers offer rebates or incentives toward the purchase of energy-efficient products. Many utilities also offer substantial discounts for consumers who sign up for a "Saver Switch" program. Visit www.energystar.gov to find special offers available nationwide. Watch local advertisements and utility bill stuffers for options.