What Direction Should a Ceiling Fan Blow to Get Rid of Hot Air?

Comfort Factors

• Several factors work together to produce the perception of environmental comfort. Three of the most important aspects are relative humidity, air temperature and air movement. When humidity stays below 50 percent, ceiling fans do a good job of keeping people cool. If the humidity level exceeds that percentage, air conditioning becomes necessary. Air movement creates a feeling of coolness at any temperature. The effect is welcome during summer's heat, but it compounds the sensation of cold in the winter.

Fan Direction

• The primary components of a ceiling fan are the central hub, which contains the motor, and the angled blades, which move air as they spin. Depending on whether the blade rotates clockwise or counterclockwise, the air will be pushed upward or downward as well as outward. When you switch a ceiling fan to the summer setting, it rotates in a counterclockwise direction and produces a cooling wind chill effect. The winter clockwise setting produces an updraft, which pushes the warm air near the ceiling downward.

Fan Size

• Ceiling fans come in many sizes. To be effective, the blades must move sufficient air mass to create a cooling or warming effect for the size of the room. According to Energy Star, small units that measure less than 36 inches in diameter are suitable for rooms of less than 75 square feet. For a room from 76 to 144 square feet, the fan should have a diameter of 36 to 42 inches. A 44-inch fan works well for a room that measures 144 to 225 square feet, and rooms of 225 to 400 square inches require fans from 50 to 54 inches in diameter.

Effectiveness

• Fans reduce the need for air conditioning because they produce airflow. As the flow moves over a person's body, it evaporates moisture on the surface of the skin. The resulting sensation of coolness permits a temperature increase of up to 4 degrees Fahrenheit without interfering with comfort. According to Samy Sadaka, a professor with the University of Arkansas, homeowners can save up to 7.2 percent in air conditioning costs for every 1.8 degrees Fahrenheit that the thermostat is increased.