How do fans make you feel cooler?

A woman sitting in front of a portable fan. — Fans do not cool air; they work by moving air around to improve sweat evaporation which in turn makes you feel cool. Sean De Burca / Getty Images

You are right -- fans actually add heat to a room. One way to think about it is like this: If you have a perfectly insulated room and you put an electric fan in it, then the room will get warmer. All the electricity that is driving the fan turns directly into heat.

So a fan does not cool the room at all. What a fan does is create a wind chill effect.

When weatherpeople talk about wind chill on a cold winter day, what they are referring to is how the wind increases convective heat loss (see How Thermoses Work for details on convection). By blowing air around, the fan makes it easier for the air to evaporate sweat from your skin, which is how you eliminate body heat. The more evaporation, the cooler you feel.

Here are some interesting links:

How Sweat Works
How does the wind chill factor work?
How does a water-cooled air conditioner work?
How Air Conditioners Work
How Car Cooling Systems Work

Frequently Asked Questions

What happens to the overall temperature of a room when a fan is operating in it?

When a fan operates in a room, it does not decrease the room's overall temperature. Instead, the fan moves air around, which can add heat to the room due to the motor's operation converting electricity into heat. However, this movement of air can make individuals in the room feel cooler by facilitating sweat evaporation, even though the ambient temperature remains unchanged or even increases slightly.

Can fans be effective in high-humidity environments?

The effectiveness of a fan in high humidity environments is reduced because the air is already saturated with moisture, limiting the rate of sweat evaporation from the skin. In such conditions, the cooling effect achieved by moving air over the skin is diminished, making fans less effective at providing perceived cooling, compared to dryer environments where the evaporation process can occur more readily.