Whole House Fans in the Winter

Whole house fans are an excellent way to increase your home’s efficiency. By providing clean, fresh air, they can create a cooling effect in the home. These machines are installed permanently into a home, so while they are often considered summer appliances, you need to consider how they will be used during colder winter months.

They are different from powered attic ventilators or attic fans and create excellent comfort in your home. Your home likely has soffit vents to help with circulation in the attic space, as well as ice damming and other issues.

This article is about whole house fans being used in the winter months to regulate indoor temperatures and reduce air pollution, generally about late November or early December through March or April. The use during these months, however, will change depending on where you live, as well as the type of winter. As we all know, winters can be mild or frigid from year to year, so there is no hard rule on when you should stop or start using a whole house fan and when you close the windows for the season.

There are many different climates in the United States, but, for the sake of this article, we will divide the country into a cold northern section and a warmer southern section. As we will describe below, each section has a unique way to use whole house fans.

closing windows to winterize home

Using a Whole House Fan in Cold Northern Regions

Much of the United States experiences warm or hot summers with cool to cold winters. In this section of the country, you will generally find that a whole house fan is effective from roughly late spring through early fall, with a break in the summer. In particularly mild temperatures, the whole house fan can be used all through the warm season, but many locations will be too hot and humid to use all summer; in this case, an air conditioner is likely needed.

If you live in a far northern region, such as the upper third of Minnesota or the northern half of Montana, you may be able to use a whole house fan all through the summer, especially if it is assisted by a ceiling fan for increased circulation. However, once winter comes around, the whole house fan becomes unusable. When the cold winds come rolling, it’s time to winterize the home, which means sealing the whole house system away for the season.


Using a Whole Home Fan in Warm Southern Regions

In warm climates, they can be used in the completely opposite manner. In areas with warm winters and hot summers, which is experienced in much of the southern United State, the whole house fan is used in the winter and sealed away, or at least not used, during the summer. The home can be assisted by soffit vents and a vent area.

In extremely hot climates, these fans simply don’t bring enough cool air into the home, even though it increased energy efficiency compared to air conditioners. Yes, it still helps with other benefits (specifically the removal of air pollution and energy efficiency), but it doesn’t give the comfortable air that we have come to expect in modern society. For this reason, most people in hot areas of the country instead use their whole house fans and ceiling fans during the winter and seal it away in the summer.


Why Use a Whole house Fan in Winter?

At this point, it helps to take a step back and examine why we should even use whole house fans in the first place. As you’ll see, these appliances bring better air into your home and can result in a more-efficient cooling system.


Air Circulation

There are many different reasons, but it essentially all boils down to air ventilation. When using a whole house fan, which is placed in the attic floor, you’ll have superior air circulation, which brings fresh, cool air into the home. With better ventilation, you’ll experience a variety of noticeable benefits…


Reduce Indoor Air Pollution

The term “air pollution” is commonly associated with being outside. Car exhaust and industrial smoke in urban areas are seen as major causes of outdoor air pollution, but indoor air can be just as bad, if not worse, than outdoor air.

Inside, you can have a wide variety of air pollutants, including dust, mold spores, and pet dander. There can also be chemicals from new fabrics, materials, and paints. All of this creates a concoction of indoor air pollution.

By using a whole house fan, you can dilute many of the harmful chemicals that become concentrated inside a house. This fan will move air from the lower floors through the attic and out near the top of the home. This process will flush the air of the chemicals and materials that make indoor air pollution so harmful.

window moisture build-up

Reduce the Buildup of Moisture

Another advantage of using a whole house fan is that you can reduce the amount of moisture in your home. Indoor moisture can come from many different sources, including leaky pipes and seepage through the foundation. When your home is sealed tight, you won’t have the chance to remove this moisture, which can lead to mold and pests.

Mold is a particular problem for air quality, as it releases spores that float in the breeze. When inhaled, these spores can irritate lungs and cause respiratory issues. If you have asthma or mold allergies, the issue can be particularly severe, so using a whole house fan in winter can be a solution.


Vent Annoying and Foul Odors

Finally, a whole house fan in the attic floor, by bringing in fresh air, can help reduce annoying odors. Have you ever noticed that a home with open windows simply smells better?

This is because house ventilation brings in fresh air and pushes out annoying household odors.

When you use your whole house fan, you will be diluting the stale, odorous air in your home. You’ll notice a fresher smell in the home because odors from pets, bathrooms, mold, and other sources are not allowed to linger.


Properly Winterizing a Whole house Fan

Homeowners in cold climates can significantly benefit from whole house fans. During the summer, they bring in a refreshing breeze, creating better breathing and superior comfort, all at a fraction of the price of running an air conditioner. However, a whole house fan in winter needs to be properly sealed.

A whole house fan is located in the ceiling of a home’s top floor, usually in a hallway where air circulation is not disrupted. Most models have a cover or closing mechanism that shuts when the fan is not running, reducing heat loss. These covers, however, do not provide a tight seal, so air can still escape. In the winter, this means your warm air could escape through the attic, reducing your home’s energy efficiency.

Stopping heat loss is essential for the overall efficiency of your home, so you will need to insulate and seal the fan box so it is air tight. Some people have tried simply throwing a blanket over the top of the box, but this doesn’t give the airtight seal that you need. A solid cover that is attached and firmly secured is much better.

One option is to create a cover out of insulation board to reduce heat loss. Using a one-inch-thick (or thicker) piece of insulation board, you can cut and a cover that is fit to the fan. Measure the cover so it will be tight to the hole, then trim to fit if needed. To blend the cover with the color of your ceiling paint, you can use white paper glued to the board. Velcro is often used to attach the cover to the whole house fan box in the winter if you are sealing it from the living space.

A cover that is accessed from the living space, as opposed to attic access, is generally preferred, as it is easier to remove. However, many homeowners prefer a cover that can’t be seen from the living space and would prefer one that is used with attic access.

If a cover that can be seen from the living space does not seem appealing, you can create an attic box to prevent heat loss. This is an airtight, insulated box that is placed over the hole from the attic. Fiberglass duct-tape can be used to create and solidify the attic box. The only issue with an attic box is that you have to climb into the attic to place it over the hole before the winter. If your attic only gives you a small crawl space, this can be difficult to use properly.


After the Winter: Getting the Whole house Fan Ready for Warm Weather

Once the winter is over, you can begin preparing your home for the warm weather. At this time, you’ll need to prep the whole house fan for the spring and summer, which means you will remove all the covers and insulation that helped keep your house warm over the winter.

You may also want to clean the whole house fan blades, as they have probably collected dust through the past few months; this is especially true if your whole house fan was sealed from the bottom and not from the top.

Before using the whole house fan, powered attic ventilator, or attic fan for the first time after winter, make sure that the attic vents are open so you have a free flow of air. Of course, don’t forget to open windows in the home as well.

Contact Oransi to learn more about advanced whole house fans. We have top-quality units that keep your home cool without a large utility bill, so contact us today!
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