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Whole-House Fans Basics

A cooling device for the summertime and hot spring and autumn days

Whole house fans are cooling devices… They are used to pull cooler outside air through open windows and exhaust hot indoor air through the attic vents and roof vents.

Whole-house fans can be extremely effective in the summertime, and hot spring and autumn days. They can lower home temperatures by several degrees in just a few minutes... if outside temperatures are cool enough.

According to EERE, whole house fans may provide 30–60 air changes per hour in a typical home.

Difference between an attic fan and a whole house fan

Whole house fans are often confused with attic fans, but they are different devices. An attic fan is usually installed in the roof in order to remove hot air from the attic (only the attic). The whole house fan (usually installed in the attic) has a much wider goal: cooling the whole home and not just the attic.

Energy savings

A whole house fan allows tremendous energy savings, comparatively to an air conditioning system: around one-tenth of the energy…

A substitute of air conditioning

Whole house fans can substitute air conditioning in summer and spring and autumn hot days, in many climates. Combined with ceiling fans they can provide good and cheap cooling comfort.

According to EERE, in most USA climates that substitution can lower cooling costs by around 30 percent.

Temperatures and low humidity

Whole house fans are typically used as a cooling device in the summertime and mid-seasons, in the early morning or late evening and at night. They are used to replace the inside air - heated during the hot part of the day - when outside temperatures are fresher (below 80 degrees) and cooler than those of inside air.

Turn Air conditioner off

Do not run air conditioner at the same time of a whole house fan. Turn it off, when using the whole house fan.

Open the windows

Open the windows (or doors), or at least some of them, when using whole house fans.

The use of a whole-house fan depends on open windows and good airflow. Otherwise, the device will not function properly, and you may damage it.

Keeping windows (or doors) open is also a question of safety. Opening windows prevent fumes, gases or flames from your own domestic appliances from being driven into your rooms – something you may want to discuss with the contractor …

Obviously, closing windows in unused rooms may also have some advantages: it will create higher velocity air movement in the other rooms…

Drawbacks of Whole House Fans

Whole house fans have obvious limitations. Their use is very dependent on outside temperatures and humidity levels and weather conditions. If outside air isn’t cool enough (or to cold) or humidity level is high, you may not use the whole house-fan.

A useful principle is to use the whole house fan when outside temperatures are below 85 degrees and humidity isn’t high.

In winter and in particularly cold climates and conditions, whole house fans are useless – and the fan opening can be a prime place for heat loss (unless sealed and properly insulated).

See: Advantages and Drawbacks of Whole House Fans

Whole House Fans Location

As a rule whole house fans are located on the highest ceiling of the house and oriented to an attic space.

See, for more details: Sizing and Installing Whole House Fans

Cost

Common whole-house fan cheap devices. Most prices range between $150 to $350, but there are other more expensive models.

See, for more details:
Investing, Prices and Manufacturers of Whole House Fans
Tips on Selecting a Whole House Fan