Can Attic Fans Cool a House?


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As the summer weather heats up, homes can get insanely hot, especially the poorly insulated ones and those in arid regions. So most homeowners let their air conditioning systems run non-stop, sending energy bills soaring. 

However, this doesn’t have to be the case. You can still keep your house cool and comfortable without scorching your wallet. You probably didn’t know this, but your attic space plays a huge role in keeping your house cool during the summer. If the attic gets too hot, the heat migrates down into your living area. This causes your AC to work harder, resulting in higher utility bills.

In view of this, can attic fans cool a house? This particular question cannot be answered with a simple yes or no. Attic fans carry several benefits, but how well they perform depends on the attic insulation, ventilation, and the climate in your region.

In this article, you’ll learn the important details about attic fans, the various types available, how they work, their pros and cons, and, more importantly, if they are worth it.

There are two types of attic fans; a powered attic ventilator and a whole house fan.

Whole House Fans

Whole house fans are usually mounted in the ceiling of a central hallway. The fan pulls cooler outside air through open windows and doors, up through the attic, and into the roof, cooling down your home. Keep in mind for the fan to work effectively; the attic needs to have a large opening to expel the hot air.

Opening windows is essential to this particular fan type performance. It prevents air suction in one spot while reducing the chances of back-drafting in your combustion appliances such as the water heater and furnace.

These fans can cool down a house within an hour. However, for whole-house fans to be effective, your house needs to be warmer inside than the outside. Also, the air outdoors should be drier than indoors.

With these conditions, the fan will use about 90 percent less energy than typical AC systems. So if you live in a hot and dry climate, these fans will do an excellent job of cooling you down and save quite a bit off your energy bill. You can even get by without an AC.

However, if you live in humid areas, this type of fan won’t do you any good. It offers little to no benefits for your home. So you are better off running the AC to keep your house cool and comfortable in the searing heat.

Another not-so-great thing about whole-house fans is that they can draw dust and allergens from outside. So if you have allergies, this might not be your best option. The bottom line is that whole-house fans are more effective and energy-efficient than air conditioning units if the conditions and climates are right.

Tip: never attempt to run a whole house fan and air conditioning unit simultaneously. Entire house fans need windows open to operate safely and adequately, while ACs need windows shut to run effectively.

Powered Attic Ventilator

A powered attic ventilator is the most popular fan found in homes. They are installed on the roof of the house or in the gable wall of your attic and maybe solar-powered or electrical.

Unlike whole-house fans, this type of fan does not pull air from the outside but instead push the hot air out of the attic and replace it with much cooler air from the outdoors via roof vents.

So they reduce extreme heat buildup in the attic and keep that heated air from seeping into your house.

The idea behind these fans is to ease your AC unit’s burden, allowing you to use less energy, thus saving you money on your summer utility bills. This is usually not the case, however. The ventilators look good on paper but can cause a host of problems.

Power attic ventilators tend to pull air from wherever they can find it. And most of the time, they suck up air from the conditioned space in your home into the attic via small openings or cracks in the ceiling. Let’s face it; most ceilings aren’t solid and perfectly air-sealed.

In other words, you’re air conditioning the attic. This creates negative pressure in your house, which increases the load on your air conditioner. This probably not a good idea if you’re trying to keep the lid on the utility bill.

Another potential problem with power attic ventilators is back-drafting water heaters and boilers due to the negative pressure in the home’s interior. If these gas appliances run concurrently with the fan, they can leak carbon monoxide. 

This can pose a deadly threat to you and your family. If you weigh the pros and cons of each, power attic ventilators won’t help much in cooling your home or reducing your cooling bills even with a perfectly airtight ceiling. On the other hand, whole-house fans can cool your house and help save energy costs, but this largely depends on your area’s climate. 

So what is the best alternative? Control the attic space by installing radiant barriers, improving air circulation and insulation in your attic.

As mentioned earlier in this post, the attic space plays a significant part in cooling your living space in summer and keeping it warm in winter. Addressing the attic air flow and insulation issues will improve your day-to-day comfort and energy efficiency. 

Installing Radiant Barrier

Radiant barriers help reduce heat transfer from the attic to your living area while allowing the AC to work more efficiently. Like a spacesuit, a radiant barrier reflects the UV heat before it warms up the air and insulation in your attic.

A cooler attic space and insulation results in a cooler home.

While radiant barriers don’t reduce heat conduction, they are quite effective in reflecting radiant heat. This is especially true if you live in hot climates. When installed properly, this reflective material can shave as much as 10 percent off your cooling bills this summer.

Improving Attic Ventilation

Proper attic ventilation allows hot air to escape from the top of the roof, keeping the heat down and prolonging shingle life.

One way of improving your attic ventilation is to install soffit vents. These vents are usually installed into the underside of the home’s eaves. The vents pull fresh outside air into the attic and expel the stifling hot air through the roof vents.

If your home is already fitted with these vents or another roofing ventilation system, you can consider adding soffit vents to increase your home’s airflow. Also, ensure the existing ones are not blocked.

Adding Insulation

Adding insulation to your attic floor can slow heat transfer to your living area. This not only helps to improve comfort levels in your house but also makes cooling bills less burdensome.

The best thing about adding insulation is that it will also keep your house warm and comfortable during the cold winter months.

When installing insulation, do not cover soffit vents. The insulation will block air flowing into them. And as stated above, the vents are crucial in increasing the overall efficiency of your house air circulation.

Remember to seal off any air leaks at the ceiling. This prevents warm air from leaking into your home from the attic while keeping out moisture.

Wrap Up

If you’re looking to keep your home cool this summer, attic fans won’t just cut it. While every household is different, the cons outweigh the pros, especially for the powered attic ventilator. The best solution is to have proper ventilation, attic insulation, and air sealing.

Steve Rajeckas

Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he's not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.

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