How Does an Attic Fan Cool?
- A popular misconception is that an attic fan cools the entire home. Not so. An attic fan, is, as the name implies, a fan for the attic.
- The attic fan contributes to a cooling of the entire home by pulling in cool air from the outside of the house through the roof vents and then pushing the hot air out through the same vents. The temperature in the attic is then dropped considerably as the new cooler air replaces the stale hot air. Consequently, as the hot air exits the attic, it contributes to a temperature drop in the entire house as well.
- In the case of a whole-house fan, also located in the attic (though sometimes also installed in a wall) the fan pulls stale air from the entire home (as opposed to just the attic), replacing it with fresh air from the outside. Again, while the purpose of the attic fan is the movement of air in and cooling of the attic, the whole-house fan moves air through the entire home by sucking air up from the lower reaches of the home, and out through the attic vents. Before turning on a whole-house fan, however, it is important to open windows in the home and close the flue to any fireplaces, as the suction created requires an influx of fresh air, be that through an open window or a chimney.
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