Whole-house fan

A typical whole-house fan, with louvers closed when not operating

A whole house fan is a type of fan, commonly venting into a building's attic, designed to circulate air in an entire house or other building. The fan removes hot air from the building and draws in cooler outdoor air through windows and other openings. While sometimes referred to as an "attic fan", it is not to be confused with a powered attic ventilator, which exhausts hot air from the attic to the outside through an opening in the roof or gable at a low velocity.[1]