You may be highly considering buying and installing an attic fan, but no one wants to commit to an addition to their home when they aren’t even sure how it works. To help you better understand the question, “how do attic fans work?” here’s our top six tips to keep in mind.

1. Removal of Hot Air: The #1 Way “How Attic Fans Work”

Attics are always the hottest space in your home, thanks to the sun’s heat seeping through the roof. This isn’t usually an issue, but too much heat in the attic can begin to seep down into your living spaces. 

An attic fan keeps this heat from building up to the point that it spreads. During the warmer Spring and Summer months, it increases the amount of hot air removed from your attic and sent back outside where it won’t affect you.

Here’s a great video of how it’s done.

2. Drawing in Cool Air

Your attic is already designed for the process of expelling hot air and drawing in cool air, but an attic fan speeds up and improves this system (1).

The attic fans just pull air through a hot attic space in an effort to reduce the infrared heat gain you feel through the ceiling of your home. If you want your home air conditioner to cool you better, then you might want one or two attic fans.

The number of fans you might need will depend on how large your attic is, your climate, and other factors discussed below.

3. An Attic Fan Works Best with Proper Airflow

Anyone asking “how does an attic fan work” has to first realize how important airflow is when learning how to cool an attic.

Anything that restricts airflow may prevent the attic fan from properly doing its job.

If there’s no airflow in your attic and hot air gets trapped easily, then the attic fan has to work extra hard to expel the unwanted air and can end up wasting energy to do so.

Attic Cooling Fan

4. Attic Fans Only Work Well If There Are Seals

While it’s true attic ventilation fans need proper airflow, like AC units, they also only work well if there are proper seals, as well. This is another huge piece of the puzzle to answering, “how do attics fans work?”

If you think about it, you wouldn’t run your AC all day with all your windows open, would you? 

Of course not! The area between your attic, roof, and the rest of your living space is typically sealed, but if not, then the fan will become a hindrance quickly.

Leaving an attic fan on with improper seals between the attic and living space will waste electricity and money.

If the seals between your attic, roof, and living space aren’t strong, then the customizable temperature and humidity settings from these attic fans can lead to an overworked machine.

5. Fan Size Doesn’t Matter 

Larger attic fans mean that they will be able to affect more air than smaller versions. Just keep in mind that you can absolutely have too much of a good thing. If your fan is more powerful than it needs to be, it could affect airflow in the rest of your home, too.

6. It Only Needs to Work When It Needs To

You should treat your attic fans like you would any other fan in the house. Its job is to cool down the attic, particularly in the hotter months of the year.

Only run it sparingly during the colder months. Attic fans can get rid of moisture buildup that could eventually lead to mold but they don’t need to run for very long to accomplish this. 

There are some top-rated solar attic fans that have a built-in thermostat so that it only turns on at certain temperatures (2). This will keep you from having to climb up into the attic over and over while also ensuring that your home temperature stays optimized. 

However, solar energy isn’t viable (yet) for everyone, so it’s important that you check if it’s right for you.

At this point, you may still have some questions about how attic fans work. Check out some of the most popular ones below.


  • Can You Run an Attic Fan All Day?

    Certainly, you can run an attic fan all day if your attic needs a lot of cooling down. Just keep in mind that the longer you run it, the greater the chance that it fully cools off your attic and starts working on your living space.

  • Can You Run an Attic Fan with the AC On?

    Yes, you can definitely run an attic fan with the AC on. Though, you might not want to.

    The idea is to save energy by reducing the run time of your air conditioner by keeping the attic cooler.” (Lana Seidman) (3)

    However, using both at the same time can reduce your energy use because, without the attic fan, your air conditioning unit might be forced to cool a hard-to-reach area (ie: your attic) with insufficient tools.

  • Why Are Attic Fans Bad?

    Attic fans can be bad if they’re left on and start to attract conditioned air from your living space. Also, if you don’t know how to install a solar attic fan or a regular attic fan, then you can run into problems with improper seals.

    To combat this, we highly recommend professional installation services for both types. For those interested in going the green route, you can check out our most important pros and cons of solar attic fans to see if they’re the right fit for you.

  1. Two Different Approaches to Cooling. Retrieved from:
  2. How to Use & Maintain an Attic Fan. Retrieved from:
  3. Ask the Expert: Is an attic fan a good investment for my home? Retrieved from: