Editing Ceiling fan (section)

===Direction===
The direction that a fan spins should change based on whether the room needs to be heated or cooled. Unlike air conditioners, fans only move air—they do not directly change its temperature. Therefore, ceiling fans that have a mechanism for reversing the direction in which the blades push air (most commonly an electrical switch on the unit's switch housing, motor housing, or lower canopy) can help in both heating and cooling.

While ceiling fan manufacturers (mainly Emerson) have had electrically reversible motors in production since the 1930s, most fans made before the mid-1970s are either not reversible at all or mechanically reversible (have adjustable blade pitch) instead of an electrically reversible motor. In this case, the blades should be pitched with the upturned edge leading for downdraft, and with the downturned edge leading for updraft. Hunter's "Adaptair" mechanism is perhaps the most well-known example of mechanical reversibility.

For cooling, the fan's direction of rotation should usually be set so that air is blown downward—usually counter-clockwise from beneath, but dependent upon manufacturer. The blades should lead with the upturned edge as they spin. The breeze created by a ceiling fan creates a [[wind chill]] effect, speeding the evaporation of perspiration on human skin, which makes the body's natural cooling mechanism much more efficient. As a result of this phenomenon, the air conditioning thermostat can be set a few degrees higher than normal when a fan is in operation, greatly reducing power consumption. Since the fan works directly on the body, rather than by changing the temperature of the air, it is recommended to switch all ceiling fans off when a room is unoccupied, to further reduce power consumption. In some cases, like when a fan is near walls like in a hallway, updraft may cause better airflow.  Another example of how updraft can cause better cooling is when the ceiling fan is in middle of a bedroom with a loft bed near a wall, meaning breeze can be felt better when airflow is coming from the top.

For heating, ceiling fans should be set to blow the air upward. Air naturally stratifies, i.e. warmer air rises to the ceiling while cooler air sinks, meaning that colder air settles near the floor where people spend most of their time. A ceiling fan, with its direction of rotation set so that the warmer air on the ceiling is pushed down along the walls and into the room, heating the cooler air. This avoids blowing a stream of air directly at the occupants of the room, which would tend to cool them. This action works to equalize, or even out the temperature in the room, making it cooler at ceiling level, but warmer near the floor. Thus the heating thermostat in the area can be set a few degrees lower to save energy while maintaining the same level of comfort.

Though reversible models of industrial-grade ceiling fans do exist, most are not reversible. High ceiling heights in most industrial applications render reversibility unnecessary. Instead, industrial ceiling fans typically de-stratify heat by blowing hot air at ceiling level directly down toward the floor.