Ceiling fans

• To operate your air conditioner unit more efficiently, turn on your ceiling fans. These fans create air movement across the skin, lowering skin temperature through evaporation. The homeowner can thus raise the A/C thermostat setting up to 4 degrees F without any decrease in comfort. Each degree you raise the thermostat above 78 degrees F you save about 7-8 percent on your electric cooling costs.
• If your ceiling fans are reversible, be sure to adjust the setting at the onset of the cooling season so that the blades turn to create a downdraft.
• When purchasing ceiling fans, remember that a 36- or 42-inch fan works best for rooms 12 feet by 12 feet or smaller. A 48- or 52-inch fan works best for rooms up to 12 feet by 18 feet. Two medium-sized fans work best in a room longer than 18 feet.

--From the National Park Service Home Greening Tips