Attic Ventilation Fans (Pros And Cons)

In this attic ventilation fans pros and cons guide you’ll see how they work, risks of having an attic fan and if its worth installing in your home.
Many homeowners look for efficient and budget-friendly ways to cool their homes during the summertime.  If you have an attic, you may have heard that attic ventilation fans are an energy-efficient way to improve your home’s ability to keep cool, even as the temperatures rise.

In this post, we will attempt to help you understand how attic ventilation fans can keep your home cool. We will look at how they work and list down important attic ventilation fans’ pros and cons to help you decide if these fans are a good idea for your home.

How Do Attic Fans Work?

When installed on your attic ceiling, an attic ventilation fan circulates the air at the top area of your home. By improving the air circulation in your attic, an attic ventilation fan helps cool your home much like a ceiling fan.

An attic ventilation fan circulates the hot and humid air that often finds its way into your attic, pushing this air out of your home’s topmost spaces. This effect is what is also known as air exchange.

During the summer months, the air in your attic can heat to as much as 150 to 160 degrees. These temperatures don’t just make the attic an uncomfortable place to be in but can also affect the temperatures in the rest of the home.

That much heat accumulated in your attic will leak down into the floor below and have a warming effect on the rest of the house. This increase in temperature will also mean an increase in the amount of work your home cooling system needs to do. The rising temperatures will mean that you need to increase your air conditioner use, driving your energy bill higher.

By decreasing the amount of hot air stuck in your attic, attic ventilation fans bring your attic’s temperature closer to the temperature outside. This allows your home cooling systems to cool the air left inside the house more efficiently. It also improves the ability of your home insulation to modulate your home’s temperatures.

While we’ve primarily focused on the benefits of attic ventilation fans in the warm months, there are also some benefits to having attic ventilation fans installed and working during the winter. 

During the colder months, the warm air inside your home meeting the cool air under your roof can lead to excessive moisture forming. Since attic ventilation fans decrease the warm air trapped in your attic, this will also keep moisture from forming on and beneath your roof. See our guide to the different types of attic fans here.

Pros Of Attic Ventilation Fans

Improves Air Conditioning Performance – One of the most commonly cited pros of attic ventilation fans is their ability to increase the efficiency of your home cooling system.

By cooling your attic, attic ventilation fans take some of the load off your home air conditioning system. If your attic temperature has cooled, you will need to use less AC to cool the rest of your home.

Keeps the Home Cooler – By keeping the temperature of your attic down, attic ventilation fans also create a cooling effect that can be felt in your home’s upper levels. Hot air trapped in the attic doesn’t just heat the attic area but can also leak heat down into the floors below your attic.

So, your attic ventilation fans keep your upper floors cooler and more comfortable by expelling the hot air trapped in your attic. This should also allow you to reduce your AC use in those areas.

It’s not just your home cooling systems that can benefit from the cooling effect of attic ventilation fans. By keeping your attic space cooler, attic ventilation fans also relieve some of the summer months’ pressure on your insulation systems. 

While most of the benefits of attic ventilation fans we’ve talked about seem to be relevant for the summer months, having fans installed and running in your attic can also benefit your home during the colder months.

Helps Cut Down on Moisture Under the Roof – Hot air trapped in the attic during cold months will react to the freezing temperatures outside and can create moisture and spots of condensation just under your roof. This accumulated moisture can damage your roof and also lead to a mold or mildew infestation in your attic.

Helps Prevent Damage From Freezing Weather – Poor attic ventilation can also result in ice dams, where snow melts on a roof, and the water drips down into the edges of the eaves and roof. The water from the melted snow then accumulates and freezes in these sensitive areas. 

The formation of ice dams can then lead to structural damage to your roof. Improving your attic’s ventilation with fans can prevent ice dams.

Cons Of Attic Ventilation Fans

Can Not Replace a Proper Air Conditioning Unit – One of the cons of attic ventilation fans comes from a misconception about what these fans can do.

Some people who install attic ventilation fans are dissatisfied as the cooling effect is “not enough.” They expect the fans to cool their home and maybe eliminate the need for them to operate their air conditioning systems. 

Remember that an attic ventilation fan removes hot air from your home, but the cooling effect this has on your attic will not be strong enough to cool your entire home.

Can Not Cool The Entire House – An attic ventilation fan will cool your attic space and the top of your home and reduce the amount of hot air entering your home. However, the cool air will not spread to and cool your whole house.

So, you’re still going to need a cooling system, such as air cons, that can work simultaneously as your attic ventilation fans to actively cool your home during the summer.

Increase the Electrical Bill – Attic ventilation fans also need electrical power to keep working, so installing a few of these fans could also make your electric bill go up. To prevent this, you need to make sure that you install energy-efficient or Energy Star certified fans.

You can also consider installing solar attic ventilation fans. As these types of attic fans generate and run on their “own power,” this will not add to your home electrical bill.  

Improper Installation May Cause a Leaking Roof –  When installing ventilation fans, make sure that the installer knows what they are doing. If an attic ventilation fan isn’t installed correctly, it could lead to roof leaks.

It’s also important to make sure that your attic is properly insulated and air sealed; otherwise, your attic ventilation fan will not have the proper cooling effect.

Are Attic Fans Dangerous?

In general, attic fans are not considered dangerous. There is, however, the risk of carbon monoxide poisoning if you also have natural gas or propane burning appliances.

Attic ventilation fans can create negative air pressure in your home’s interior; if this happens, the carbon monoxide emitted by your gas-burning appliances can be sucked back into your home. 

You should have carbon monoxide detectors installed in your home to prevent the carbon monoxide levels in your home from rising to dangerous levels. Cracking a few windows at a crucial moment can help ensure your safety. 

You might also consider not running your attic fans and your natural gas-burning appliances simultaneously. 

Do Attic Fans Really Work?

The answer to whether attic fans really work mainly depends on what you expect from them. For the most part, attic fans provide an efficient way to keep your attic temperature under control and help prevent a host of problems during the summer and winter months.

Attic fans effectively circulate the air in your attic, keeping the attic temperature close to the temperature outside. Keeping your attic temperature down during the summer will help keep your home cooler.

Meanwhile, during the colder months, keeping attic temperatures down will keep moisture from building in your attic and roof, preventing structural damage and the growth of mold and mildew.

If you are worried about the possible costs of running an attic fan, you can turn it on and off as needed. You can monitor the temperatures outside or monitor the temperatures in your attic and only turn on the fans when needed. 

You might also consider getting attic ventilation fans with a timer or thermostat setting. Set the thermostat of your attic ventilation fans to about 100 or 110 degrees Fahrenheit and the fans will turn on and off accordingly when the temperature in the attic rises.

Do You Need An Attic Vent Fan?

If you live in a cold or temperate climate, where the temperatures never go above 80 degrees, then installing an attic fan might not be worth it.

This is especially true if your ultimate goal for installing attic vents is to improve your home’s energy efficiency. Installing attic vent fans and keeping them running when they are not really needed will actually waste more energy than it will save.

If it doesn’t get that hot or cold in your area, you might not have too much of a problem with attic temperatures. Instead of attic ventilation fans, you might want to look into and install passive roof vents. You should also consider just adding more insulation or air sealing your attic.

See more related content in our article about the different types of attics here.