Fans do not actually cool the air in a room, they just move it, but they make you feel cooler through a process called wind chill and evaporation. A fan works by circulating air and increasing airflow across your skin, which helps evaporate sweat more quickly, and evaporation removes heat from your body, making you feel 5 to 10 degrees cooler even though the air temperature in the room stays the same or even rises slightly due to motor heat. A thermometer placed in front of a fan will not show a lower temperature. Air conditioners, on the other hand, use refrigeration to remove heat from indoor air and release it outside, actually lowering the temperature. This is why running a fan in an empty room does not cool the room and wastes energy, you should only run fans when people are present to feel the wind chill effect. However, fans do help distribute cool air from an AC more evenly and can make a room with AC feel cooler so you can set the thermostat higher and save energy. In a workshop or garage, high-velocity air movers can make you feel much more comfortable even though they are just moving hot air. So fans improve comfort by moving air, not by lowering air temperature, which is an important distinction for energy use and cooling strategy.
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