Ceiling fans are generally more expensive than portable fans; but like portables, they produce a cooling effect by moving air across the surface of the skin; and thereby making people feel cooler. While operating, losses from the motor actually heat the space in which they operate, therefore, they should only run when someone is there to appreciate their cooling effect. When no one is in the room, keep ceiling fans off.
Ceiling fans are usually mounted at the center of the room where the room's light fixture would normally go. For this reason, they often contain their own lighting fixture just below the fan blades. It is important to keep lighting below the blades because lights above them will appear to flicker psychedelically when the fan operates.
If you are planning to purchase a ceiling fan, be sure to get one sized properly for the room. Do this by measuring your room area (length times width) and looking for a fan with the appropriate fan diameter.
Minimum Fan Diameter
Some ceiling fans offer reversible operation; they can blow "down" in summer when the breeze will create a cooling effect, and up in winter to circulate warm air that has risen to the ceiling. This feature is particularly advantageous in rooms with high ceilings that trap "warm' air during the heating season.