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Can You Run a Whole-House Fan All Night?

With temperatures and cooling costs rising all the time and taking a chunk out of the household budget, homeowners may find whole-house fans to be the most affordable solution to cooling their homes. Often used by many in the past before air-conditioning became available, they are now getting upgraded with new smart designs that are quieter and more efficient than the old models. However, it’s still important to know how and when to run them.

You can run a whole-house fan all night. This is the best time to run it, because the air is cooler. It works by bringing in cooler air from the outside and removing warm air within the spaces and walls of the house. Running it all night is important because it takes time to remove the stored heat.

The following will explain why it’s good to run these fans all night, what they do for you, how they work, and how to use them. Also discussed are how their use compares to running the AC, benefit-and cost-wise. Finally, within this summary, you’ll find installation musts and recommendations.

Can you run a whole-house fan all night

What Do Whole-House Fans Do?

According to the U.S. Department of Energy (DOE), the whole-house fans cool and provide fresh air to the entire living space of the home, in addition to providing good ventilation for the attic. Running them to bring in the night’s cooler air significantly reduces the next day’s air conditioning load.

Depending on the location of the home, its layout, and other factors, these fans “should provide houses with 3 to 6 air changes per hour,” according to the DOE. So, if used correctly, they greatly reduce your cooling bills. Typically, the fans “use about one-tenth of the electricity of comparably sized air conditioners,” adds the California Energy Commission (CEC) website.

How Do Whole-House Fans Work?

These fans work by pulling cooler air from outside in the house through open windows and exhausting the warm indoor air through roof vents. During warm or hot days, houses store a lot of heat within their spaces and walls.

Can You Run a Whole-House Fan All Night?

Even when the air cools down after sunset, the house continues to radiate that stored heat, keeping it warmer than the outside air. Drawing in the outside night air quickly cools down the interior and then gradually, throughout the night, draws out the stored heat, making it easier to cool with AC the next day.

How Is Using Whole-House Fans Superior to AC Cooling?

These fans push out hot air from the entire house through the attic and roof vents. This cools down attics, which can reach temperatures exceeding 120 degrees on hot days. Using air conditioning at night to cool down the house works also, but it is much more costly, and it also doesn’t always adequately cool the upstairs, much less the attic.

No matter how well the home is insulated, air conditioners alone will not cool hot attics. And attic heat can seep down into the rest of the house. These fans also clear out the stale air that recycles in the living space when windows are closed during the day.

What AC Can Do That Whole-House Fans Cannot

For one, HVAC systems can cool with minimal noise, while whole-house fans can be loud, some really loud. Also, using air conditioning avoids exposure to pollen and other irritating particles from outside air, something that allergy sufferers may find essential. And, when it’s humid outside, air conditioning is usually preferred.

Drawing humid air into the home can be much more uncomfortable than the extra cost of running AC. Also, when the outside air is more polluted than inside, which is often not the case, it’s best to cool with AC, which doesn’t draw in the outside air, but instead sucks hot air out of the house using a compressor.

You can listen to the sound of different whole-house fans here:       

What Is the Best Home Location or Climate for a Whole-House Fan?

According to Ecotelligent Homes, the ideal climate is cool and dry. However, the question would be, why do you need these fans where the climate is cool? The source makes this clearer by adding that the perfect area would be one that has a much cooler nighttime than daytime temperature.

Also, consider that a whole-house fan does more than cool the house’s interior. It also brings in the fresh air, so you might want to use it to clear out stale, recycled, or even toxic indoor air, so long as the outdoor air is not more contaminated.

Even though whole-house fans are best suited for dry climate areas with cool nights, innovations in the design of these fans allow homeowners in areas where the climate is less ideal to benefit from their use as a supplement to AC.

How Easy Is It to Install a Whole-House Fan?

First of all, says CEC, the installation of whole-house fans is relatively inexpensive compared to HVAC systems. The fans are most often installed in hallway ceilings just below attics. However, the DOE says the installation can be tricky. So, you should consult a contractor to help decide the correct fan capacity and size, along with the number of attic vents needed, because these are powerful fans that require proper attic ventilation. explains that you will probably need to increase attic ventilation to “2 to 4 times the normal area of attic vents.” The DOE also emphasizes the importance of having an easy-to-open, “tightly sealed, hinged door for the fan opening” to use when switching cooling methods. As for noise concerns, recommends that rubber or felt gaskets be included with installation. insists that “the fan unit must provide a positive air seal,” so that no heated air leaks into your cold attic during winter months, which can cause all kinds of condensation problems.

PurSolar & Electrical of Arizona advises installing an attic fan along with a whole-house fan.

What Type of Whole-House Fans Are Best?

The newer, smart fans are definitely recommended over the old. Ecotelligent Homes advises that if you have an old one, replace it because the old ones are not only much noisier. They are less efficient and often not properly sealed, leaking hot air into the living space in summer and heated air into the attic in winter.

It seems that the best new fans may be the costliest, but they still are well worth the investment if installed and used properly.

One sold by Centric Air, its QA-Deluxe, is one of the highest-rated on Amazon.

QA-Deluxe 5500(W) Energy Efficient Whole House Fan | 2-Speed Wall Switch & Timer | R-5 Insulated Damper | 3945 CFM HVI-916 Certified Airflow Rating | 2-Story Homes to 3400 sqft & 1-Story Homes to 2400
  • Make sure all or at least most of the windows are open when you turn on the fan. Opening windows helps circulate air and prevents gas-appliances fumes from being drawn back inside.
  • Only run these fans when the temperature outdoors is cooler than inside, usually below 80° F (26.7° C).
  • Don’t run the fan when outdoor air is polluted or damp.
  • Don’t run the air conditioner at the same time the fan is running.
  • Do open the windows, turn the fan on at night, and leave it running until morning.
  • To cut down on noise, lower the setting on a multi-speed fan.
  • Consult a professional before choosing or installing a whole-house fan.
  • Make sure there is adequate attic space and attic ventilation for the power of the fan installed.

Can You Run a Whole-House Fan All Night?


If you have decided that a whole-house fan is right for your climate, floor plan, and all other considerations, then, by all means, run the fan anytime the air outside is cooler than inside your house, including all night. whole-house fans are designed to run all night and into the early hours of the morning.

This, of course, means you do this when you want the indoors to be cooler, and you’re willing to turn off the AC and open most of the windows. Do make sure that the outside air quality is good when you run this fan because it will be bringing into your home any toxins that might be in the outside environment. Using these fans and saving energy is just one-way homeowners can help ameliorate climate change.


  • Steve Rajeckas

    Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he's not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.

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