How Does an Attic Fan Work?

Picture this: you’re opening up your first utility bill of the summer, cold lemonade in hand. You’re proud of yourself for keeping the air conditioner on a reasonable temperature, and you feel relaxed as the bill slides out of the envelope.  

But then you read the total—and it’s far more than you anticipated. 

Keeping your home cool is difficult during the warmer months with outdoor air reaching high temperatures. It can be even more difficult if your attic space is not properly ventilated and insulated. An attic fan is one popular method of attic ventilation. But, how does an attic fan work? And is an attic fan installation really the answer to your summer cooling issues? We’ll explain in this guide.

Pros and Cons to Using an Attic Fan

An attic fan is almost exactly what it sounds like: a fan installed in your attic to move warm air out of your home and add cooler air into it.  

How well do they work?

On one hand, attic fans can be very useful in locations that are cooler in the evening, such as Portland or Seattle. On the other hand, they don’t work as well in consistently warmer places like Arizona and California and are less efficient than other options.

Let’s dig in.

Pros of Attic Fans

There are a few reasons why an attic fan might be a step in the right direction when thinking about caring for your home and those in it:

  • Attic fans use less energy than air-conditioners Many homeowners use thermostat-controlled attic fans to ensure further efficiency of maintaining attic temperature. This means that when the attic hits a certain temperature, the attic fan will immediately start and keep working until the attic has dropped below the set temperature. As a result, you save money and use less energy.
  • Attic fans can also keep moisture out of your home – Sometimes, cool A/C air and hot attic air can combine to form moisture in your attic space, creating an ideal environment for mold. Attic fans work by pushing hot air out to prevent a buildup of harmful mold.1 Therefore, an attic fan can protect the wood in your roof and ceilings and improve its longevity.

Cons of Attic Fans

Energy savings and protection from mold seem like great perks. So, then what are the negatives of attic fans? In short, attic fans may not be as helpful as they seem:

  • They need very specific circumstances to work effectively Attic fans are not useful in all environments. If there is not cool enough air outside, then the attic fan will simply replace the hot air in your attic with more hot air. This could cause your attic fan to work overtime and ultimately would not keep your attic cool. 
  • They do not work as well when used in conjunction with air conditioners – Why not? Energy Star explains that “if your attic has blocked soffit vents and is not well-sealed from the rest of the house, attic fans will suck cool conditioned air up out of the house and into the attic.”2 Furthermore, keeping windows and doors closed (as you’ll want to when using A/C ) is not advisable with attic fans. 
  • They can be expensive and inefficient – An attic fan is just one more expense on your electricity bill. Even if a fan does reduce your need for air conditioning, you may not see any savings. Additionally, they won’t work to cool your entire house, which may not provide any benefits during the warmer months when temperatures can reach the triple digits. Instead, attic fans only circulate air within the upper portion of the house. 

This means that an attic fan could end up costing you more money in the long run, especially if used in conjunction with an air conditioner.

Even more importantly, if your attic is not well-insulated and does not have proper ventilation, the attic fan yet again loses its energy efficiency. 

The good news? Proper insulation and ventilation can have the same positive impact as an attic fan, helping keep your attic cool, dry, and inhospitable to mold.

Keep Cool With Attic Construction

When thinking about all of this information, it is easy to get overwhelmed. How can you best protect your home from external heat and moisture? We’re here to help. 

When an attic is properly insulated, it restricts the movement of air, which will save energy and money while keeping hot air out. Proper installations of soffit vents and ridge or gable vents also help to facilitate the proper type and amount of airflow to keep things like mold away from your roof and ceilings. 

Having up-to-date attic insulation and attic ventilation that is well installed is the key to your home’s success. At Attic Construction, this is our specialty and we’re here to provide insight on common attic insulation mistakes to avoid. 

With professional help, an attic fan may prove unnecessary altogether, and you‘ll still be able to keep those bills lower and your home cooler. For more information on concerns like preparing an attic for cold weather or detecting thermal leaks, visit Attic Construction today for a consultation. 


  1. Home Inspector Secrets. My 7 Pros and Cons of Vent Fans.
  2. Energy Star. About Attic Ventilation.

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