HOW CEILING FANS WORK
First, a confession: Fans donít cool air; they just move it around.
When itís warm, the blades of a counterclockwise-turning ceiling fan push air downward. Like a breeze on a summer day, this moving air makes you feel cooler by evaporating the moisture on your skin. This wind-chill effect can cause an 80-degree room to feel more like itís 72 degrees. For this reason, there is no need to run a ceiling fan when no one is in the room.
Something else: Most people donít think to turn on a ceiling fan when itís cold inside, but this can actually warm up a room. Modern Fans have reversible motors, which means blades can easily change direction (clockwise) and push air up toward the ceiling. This redistributes the warm air that would otherwise be trapped near the ceiling and evens out the temperature in the room. More...