It's not the fan that keeps you cool

Original post:  Aug 26, 2015

If you are in the northern hemisphere, it is likely that you are enduring a hot, sticky summer. It seems that worldwide temperatures are soaring. Fans can often help beat the heat.
How would you answer this question?

Let me add a little more information for you. Did you know that ceiling fans (and all electric motors) generate a fair amount of heat when they run? Here is an infrared picture that illustrates it:

While it might seem that moving air brings blessed relief and cooler temperatures, it isn't really the fan doing the work. It actually is the evaporation that occurs when the wind circulates the air past your skin that cools you.

This article in Wired helps explain the concept. It showed that a fan in an enclosed box simply increased the temperature of the box as it ran because of the heat generated by the motor. It also showed that a paper towel dipped in hot water (warmer than room temperature) actually ended up cooler than room temperature before a fan is turned on and dips significantly once the fan evaporates more of the water!  Why Fans Don't Always Make Things Cooler | WIRED

To answer the question above, here is a hint from the original article:

FixIt:  Fans do not cool a room; they cool the people in the room.

Here is the link to the full answer there:  Ceiling fans on or off when room is empty? | The Seattle Times