Central air conditioning has increasingly become a standard amenity in American homes since it become popular in the mid-20th century, and with good reason. Cool air makes it difficult for allergens such as mold and dust mites to thrive, and it provides respite from warm outdoor weather. With excessive use, however, it can contribute significantly to energy costs each month.
A standard air conditioning system uses about 3,500 watts, according to the Otter Tail Power Company of Minnesota. At a usage of 860 hours during the cooling season, or summer, that's just over 1,000 kilowatt-hours of usage per month. This translates to a monthly cost of about $116 as of 2011.
Otter Tail bases its figures on a 2.5-ton air conditioning unit, which is suitable for a home up to 1,200 sq. ft. If your home is larger than 1,200 sq. ft., your monthly cost for air conditioning may be higher. If it's smaller than 1,000 sq. ft., it may be lower; it largely depends on how much you use air conditioning. If the temperature is moderate year-round where you live, you may use it less than Otter Tail estimates.
Central Air vs. Ceiling Fans
Ceiling fans and portable fans use between 65 and 250 watts, which is, at most, 7 percent of the wattage an air conditioner requires. If you left a fan on 24 hours a day for three months, it would only cost you $16 to $63 total. The major drawback is that a fan doesn't chill air as a central air conditioner does.
Getting the Most Value
For the most value, money management software company Money Allocator suggests setting the thermostat no lower than 78 degrees. Turn on a fan to circulate air throughout the room, and you can keep your home at a relatively comfortable temperature.
- Otter Tail Power Company: Appliance Energy Usage
- U.S. Department of Energy: Estimating Appliance and Home Electronic Energy Use
- U.S. Energy Information Administration; Electric Power Monthly; June 2011
- Money Allocator; Tips for Buying an Air Conditioner; Sierra A. Martin
- U.S. Department of Energy; Central Air Conditioners; February 2011