And while we may take AC for granted, it's generally an expensive luxury. That accounts for at least 6 percent of all energy used in some homes.If you're shopping for a new air conditioner, you'll notice quite a few different sizes and models.Here's a quick primer on staying cool and keeping your wallet from overheating while picking out an AC unit.Keeping cool and comfortable in the summer and watching your electricity usage can be a challenge. Your home's heating and cooling system uses about half of your total electricity. Want to find even more ways to save energy and money? Sign up for Online Services today and get personalized recommendations just for you! Make sure your central air conditioning system or window unit is properly sized for the space it is intended to cool. Improperly sized units use more energy than necessary. Remember that window air conditioning units generally are not designed to cool more than one room. Clean or replace window unit or central air conditioning system filters monthly.

Dirty filters cause air conditioners to work harder and use more energy. If you have a central air conditioning system, do not close off unused rooms or close air registers in rooms. The system will be less efficient and will cost more to operate. Make sure an outside air conditioning unit or heat pump is not blocked by shrubbery, leaves or other objects. Set the thermostat on the highest comfortable setting. Raising the temperature just 2 degrees can reduce cooling costs by as much as 5 percent. Check weather stripping around doors and caulking around windows. Properly sealed doors and windows help prevent warm outside air from entering the home. Close blinds, shades or drapes during the hottest part of the day to block the sun's heat. Make sure the attic is properly ventilated to relieve excess summer heat. Duke Energy recommends one square foot of free area for every 150 square feet of total attic floor space. Place heat-producing appliances such as lamps and televisions away from the air conditioning thermostat to prevent inaccurate temperature readings.