A whole house fan is a type of fan, commonly venting into a building's attic, designed to circulate air in an entire home or 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", this term properly refers to 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.

Description

A whole house fan pulls air out of a building and forces it into the attic space or, in the case of homes without attics, through an opening in the roof or an outside wall. This forces air from the living areas into the attic and out through the gable and/or

soffit A soffit is an exterior or interior architectural feature, generally the horizontal, aloft underside of any construction element. Its archetypal form, sometimes incorporating or implying the projection of beams, is the underside of eaves (to ...

vents, while at the same time drawing air from the outside into the living areas through open windows. Powered attic ventilators, by comparison, simply push hot air out of the attic to facilitate the intake of colder air into the structure.

History

Before the development of

electrical power Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions of ...

the principle of cooling a building by designing it to draw in cooler air from below and vent it from the top was known. In the absence of the forced air movement produced by a fan, careful design to promote cooling air flow was required.

Thomas Jefferson Thomas Jefferson (April 13, 1743 – July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Fathers of the United States, Founding Father who served as the third president of the United States from 18 ...

, US president from 1801 to 1809, was personally involved in the designs of his residences at

Monticello Monticello ( ) was the primary plantation of Founding Father Thomas Jefferson, the third president of the United States, who began designing Monticello after inheriting land from his father at age 26. Located just outside Charlottesville, V ...

and

Poplar Forest Poplar Forest is a plantation and plantation house in Forest, Bedford County, Virginia. Founding Father and third U.S. president Thomas Jefferson designed the plantation, and used the property as both a private retreat and a revenue-generating pl ...

, and was aware of these techniques. Monticello had a large central hall and aligned windows designed to allow a cooling air-current to pass through the house, with an octagonal cupola at the top of the house drawing hot air up and out through natural convection. Whole house fans were the only method for cooling homes in the early 1900s. Air conditioning was invented by Carrier in 1907 but did not become popular until the 1950s. Whole house fans are still ideal for cooling homes when the air outside is cooler than the air inside.

Types

There are four types of whole house fans: # Ceiling-mounted: Mounted in the ceiling between the attic and living space. # Ducted: Remotely mounted away from the ceiling, typically hung from the

rafters A rafter is one of a series of sloped structural members such as Beam (structure), wooden beams that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof Roof shingle, shingles ...

; can exhaust heat from multiple locations; operation is extremely quiet. # Window-mounted: Mounted in a window frame. Can also take cool air in from outside. # Rooftop-mounted: Suitable for homes with no attic.

Gallery

File:Whole-house-fan-pre-install.JPG, Fan unit before installation File:Whole-house-fan-on-freeze-motion.JPG, Louvers open while fan is operating File:Whole-house-fan.ogv, Video of a whole-house fan in operation

References

External links