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How Ceiling Fans Save Energy
Fans used to supplement air conditioning save energy by permitting a higher thermostat setting. Air movement from the fan evaporates moisture on the skin and makes a person feel cooler. With this cooling effect, most people can raise their thermostat and feel just as comfortable. For every degree you raise the air conditioning thermostat above 78 degrees, you can save 3 percent to 5 percent on cooling costs. However, there are no energy savings if you use a ceiling fan and do not raise the air conditioning thermostat.
How to Select a Ceiling Fan
Fan sizes commonly range from 34" to 56" in diameter. The best size for you will depend upon the room where the fan will be installed. Generally, a 36" fan is suitable for rooms that measure up to 9' X 12'. A 48" fan is practical for rooms up to 12' X 15', and a 56" fan suits rooms larger than 12' X 15'. A long and narrow room may require two fans for effective air circulation. Avoid too small a fan – it won't produce the cooling breeze you expect.
Reversible Ceiling Fans
Reversible ceiling fans are often promoted as a way to save on heating costs during the winter. But just like fans used in the summer, a reversible fan produces air movement that could create a chilling effect. So it is unlikely you'll feel any warmer. Savings can be realized, however, if you adjust your thermostat in addition to reversing your fan. The reverse cycle will help to pull heat from the ceiling and push it downward. For each degree you lower your thermostat, you'll reduce heating costs 3 percent to 5 percent.
How Much Energy Do Ceiling Fans Use?
Fans use no more electricity than light bulbs. Typical wattages for various ceiling fan sizes are:
- 36" = 55 watts
- 48" = 75 watts
- 52" = 90 watts
- 56" = 100 watts
For example, a 48", 75-watt fan used 10 hours a day at half speed or less would cost $.50 to $.90* a month to operate. For a 1,500-square-foot house with air conditioning using two ceiling fans and raising the thermostat setting could save about $70 to $200* over a six-month cooling season.
Prices
Ceiling fans can cost anywhere from $30 to more than $1,000, but most are sold in the $50 to $100 range. You can recover your investment in a fan through the energy savings you achieve with a higher thermostat setting. The more a fan costs, the longer it takes to recover your investment.
Portable Fans
Portable fans save energy too. In the spring and fall when the night is cool, use a portable fan in your window to blow cool air into your house either late at night or early in the morning.
* Savings are calculated at $.08/kWh for simplification and are based upon engineering assumptions and approximations. Actual energy savings may differ from those estimated due to variations in weather, individual energy use habits and home characteristics.
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