How Does a Whole House Fan Work

If you are searching for an affordable method to ventilate and cool your home, perhaps a whole house fan is just the right thing for you.

These are an excellent addition to an existing ducted air conditioning system, as they rely purely on pushing the hot air out of your home while bringing fresh, cooler air in from outside.

In this article, we’ll answer the question ‘how does a whole house fan work?‘, how are they different from other types of fans, as well as some do’s and don’ts.

How Does a Whole House Fan Work?

A whole house fan is designed to help you circulate the air through your home. The fan pulls outside air into the home through windows, which means that you should leave them open while the fan is working, and fills your home with fresh air from the outside.

At the same time, negative pressure is being formed inside the home, resulting in positive pressure in the attic.

This further leads to building the pressure inside the attic that will be released by pushing the air out through the vents that were previously built-in in the attic, or through the eaves.

The result of the whole process is that your entire home is being cooled. Those rooms where you leave windows open will benefit from this the most.

Why Use a Whole House Fan?

If you are feeling hot at your home, sure, you can switch on your air conditioner. However, many people complain about feeling unpleasant after spending long hours in a room with air conditioning.

A whole house fan is a great alternative, and it’s a completely natural solution, based on simple rules of physics, therefore, they don’t cause unpleasant side effects such as headache, nausea, or even allergic reactions (usually in the case of uncleaned filters in the AC unit) that sometimes occur when using an air conditioner.

When it comes to energy expenditure, whole-house fans are far more efficient than AC units, as they use significantly less energy. They are environmentally friendly, as there are no refrigerants used for cooling.

The air circulation through the home is constant, meaning that you can keep your home odor-free throughout the day, regardless of whether you’ve been cooking spicy food, if you have pets, or have smoked inside.

Finally, whole-house fans are very durable, and most households enjoy their benefits for many years, without having to do any serious maintenance.

Whole-House Fans vs Attic Fans

At first sight, the whole-house fan and the attic fan seem kind of similar. They both will cool down your indoor space and you can attach them to your attic. However, they do different jobs.

The whole-house fan usually pulls the fresh air in through the windows. It works very fast and needs less than a full hour to cool down your indoor space. Of course, if the outdoor temperature is very high, it’s going to be similarly warm inside.

The attic fan also cools the indoor space down but uses a different method. The role of the attic fan is primarily to remove the hot air out of the attic. This is more limited than the whole-house fan, yet, both types of fan are helpful when it comes to lowering your energy expenditure and cooling down your home.

However, a whole-house fan has an almost instantaneous impact on your indoor air temperature throughout the whole house, while an attic fan takes more time to provide the indoor space with cooler air.

Whole-House Fans vs Central and Window Air Conditioners

One important thing to note about whole-house fans and air conditioners is that you can have them both, however, you should never use them at the same time.

It is okay to use them in a complementary fashion. If the AC is switched on, you shouldn’t turn off your whole-house fan. When you feel like you’ve had it with your AC, you can turn it off, and put the whole house fan on, so that you spread the cold air around and continue cooling down the house.

The main difference between these two types of systems is that the central AC cools the air by reducing moisture whereas a whole-house fan simply brings in the air from outside. Usually, air conditioning devices cool and circulate the air inside your home, but they don’t bring any fresh air from the outside. You are also usually recommended to close the windows so that the cooling of the indoor space with an AC is more efficient.

Whole house fans are designed to always provide you with fresh outdoor air, and they use no chemicals. In this process of pulling the fresh outdoor air in while letting the hot indoor out, they use up to 90% less electrical energy than the airconditioning system.

How to Use a Whole House Fan Properly

Although using a whole-house fan is quite straightforward in the end, there is still a right and wrong way to use it.

In order to help you yield the most benefits of using a whole-house fan, we have prepared this 4-step guide on how to properly use a whole-house fan.

Step 1

When you set the whole-house fan to start operating, make sure that you leave a window or door open in those rooms that you wish to cool down. The only way to achieve the optimal effectiveness of the whole-house fan is to have it operating alongside slightly open windows, but only in those rooms that you want to cool down and use. If there are rooms that you don’t occupy and don’t need to use, then close their window to achieve optimal airflow through the house.

Step 2

Turn the fan on manually. It’s recommended to do it like this, as it helps you not forget to open the windows. Making a backdraft is very important for the proper functioning of a whole-house fan.

Step 3

Once switched on, the whole-house fan will start pulling the fresh air from the outside inside, and pushing the hot indoor air outside through the roof vents. This way of cooling down your home has shown the be extremely effective.

Step 4

Once the house is cooled down to the desired temperature, and especially if the outdoor temperature begins to rise, you should close your windows in order to preserve the cool air.

Some Dos and Don’ts of the Whole-House Fans

When it comes to using the whole-house fans, make sure to do the following:

  • Read the instruction manual.
  • Ask the person who is installing the unit to tell you how many windows should you keep open while the whole-house fan is working to achieve the best cooling effects and avoid creating a backdraft or drawing in polluted air.
  • During winter when you probably don’t plan to use your whole-house fan make sure to cover and seal it, as otherwise, you will be losing heat and wasting money on your energy bills.

Also, you should definitely avoid the following:

  • Using the whole-house fan on humid days.
  • Using the whole-house fan at the same time as the air conditioner.

When Should I Run the Whole House Fan?

Of course, you can run your whole house fan whenever you want, however, the best effects will be achieved if you capture the time of the day when the air is the coolest. This is usually during the night and early in the morning. It’s also good if the weather is dry and the outdoor temperature is also the temperature you want to achieve indoors.

How Do I Know the Size of the Whole House Fan that I Need?

In order to achieve the optimal effects of a whole house fan, you should pick the optimal size for the home you live in. Too small fans may not be able to cool down your entire space, while the large ones might be overkill for your space.

The sizing of the fan is usually determined based on three factors:

  1. How big is your house in square feet, basement excluded?
  2. What is the level of cooling that you want to achieve?
  3. Is there anything in your attic that has a pilot light that cannot be turned off?


We hope you found our article on whole-house fans useful and insightful. Whole-house fans are very effective and fast home-cooling solutions, especially compared to air conditioning systems.

If you want to lower your electricity bills, but also save nature and your health from potentially hazardous chemicals, we strongly recommend purchasing a whole-house fan. Another advantage to this unit is that it’s so simple in structure and functionality that it almost never breaks.

This means that the investment once made will last years without you having to worry about it.