I was just on a road trip and read this in a paper on the way:
We are running this fact again because so many wanted to see it explained again. If you want to maximize the cooling of your ceiling fan, before making the blades turn faster, make sure they are going in the right direction.
The paddles on a fan should be turning counterclockwise to keep a cool breeze circulating. Even if you have more than one fan, side by side, make sure ALL of the fans are spinning in the same direction. Clockwise rotation (as you are looking up at it) will heat the area below.
So remember, counterclockwise means cool, clockwise means warm.
Is this acurate? I can see this working if the fan blades are angled in to the direction of the motion, but what about a ceiling fan where the blades are horizontal?