Introduction
To maintain homeostasis, the body constantly regulates its temperature between 98 and 100 degrees Fahrenheit. This regulation is performed by the hypothalamus gland. As your body temperature raises above approximately 98 degrees, your body begins to sweat. Although sweat alone is adequate in helping the body cool itself, when sweat is introduced to a fan, the cooling process is accelerated.
Heat of Vaporization
The body cools itself down by the action of sweat evaporating off the body. This action is called the "heat of vaporization," or the amount of energy that is needed to convert sweat (water) on the skin from liquid to vapor form. For water, the heat of vaporization is 540 calories/gram. This means that for every gram of water in the form of sweat on the skin, the body can remove 540 calories of heat energy, which cools the body.
Fans
Fans increase the abilities of the body to cool by increasing the level of evaporation of sweat off the body. Fans cause air to move across the surface of the skin. As the air rushes by, it pulls heat and moisture away from the skin, allowing the body to get rid of heat and moisture faster. Fans can also cool you if they are sucking warm air out of the room (such as a fan in a window facing outside), or by sucking cooler air into a room (such as a fan pointing towards a room sucking air from the outside), which reduces the overall temperature of the room.
