Cold air is heavier, it tends to go down. Hot air is lighter, it tends to go up. Ceiling fans are being utilized using this principle.
During summer, your ceiling fan should run counter clockwise to force the room air down to you giving you a cooling effect. During cold season, running your fan clockwise at a low speed will help the warm air down.
The problem, however, with ordinary ceiling fan is that it produces too much noise while running. If you are planning to buy a ceiling fan, check out Hansen Wholesale Ceiling Fans. You can call them at 1-800-201-1193 and a fan expert will answer your queries.