Does It Cost More Energy when You Leave Ceiling Fans Running All Day?

Wattage Comparison

• Otter Tail Power Company estimates that a 2.5-ton central air-conditioning system uses 3,500 watts of electricity. Such an air-conditioning system is adequate for a home of 1,000 to 1,200 sq. ft., so your system may have a higher or lower wattage. Ceiling fans, by comparison, use 100 watts on average.

  Your electric company charges you by the kilowatt-hour, which is the wattage of an appliance divided by 1,000, then multiplied by the number of hours you use it. At the rate of 11.64 cents per kWh --- the national average as of March 2011 --- it would cost you about $293 to run a 2.5-ton air-conditioning system constantly for a month, and about $8 to run a ceiling fan.

Considerations

• It's unlikely that your air-conditioning system runs constantly, even during the summer. Otter Tail estimates that the average household air-conditioning system runs for fewer than 36 days total during the entire cooling season, or warmer months. Even so, it's unlikely that an air-conditioning system can cool your home at a cost comparable to that of running a ceiling fan, even if you use the fan 24 hours a day throughout the summer.

Other Differences

• Ceiling fans make you feel cool by blowing air across your skin. Central air-conditioning systems, on the other hand, work by chilling the air throughout your home. This isn't entirely efficient, because the air-conditioning system is working to cool warm air as well as the air around you on the ground. Ceiling fans also circulate fresh air throughout the home if you use them with the windows open.

Getting the Most Value

• Air-conditioning systems use less energy when there is a smaller difference in temperature between the indoors and outdoors. MoneyAllocator.com suggests you set your thermostat to 78 degrees Fahrenheit and turn on your ceiling fan for an energy-efficient solution to summer heat. Money-saving expert Michael Bluejay suggests flipping the switch on your ceiling fan to make it push air downward. Although this pushes warm air down from the ceiling, it prevents warm air from moving up, across the ceiling and back down into the room.