What Factors Do I Need to Consider When Sizing a Whole House Fan?
So you’ve decided to buy a whole house fan… congratulations! Before long you’ll begin enjoying the cooling comfort and energy savings of your new appliance. But before you jump in and make a purchase, there are some factors you need to take into account, because not all whole house fans are the same.
There are a number of considerations that differentiate one whole house fan from another, and one of the most important is sizing. Whole house fans are not one size fits all. Get a whole house fan that’s too small for your home and it’ll be ineffective, get a fan that’s too big and it could create uncomfortable pressure differences in the house and waste energy.
Below, we’ll go over some factors to consider when sizing your whole house fan.
1) Square Footage
Square footage is probably the most important factor to consider when buying a whole house fan. How big your home is determines how much air is inside it, and therefore how much power your whole house fan needs to have to circulate this air.
Cubic feet per minute (CFM) measures how much air your fan can move per minute. A high CFM means a more powerful fan that is suited to larger spaces, while low CFM fans are for smaller homes and spaces.
So how do you choose a fan that matches the right CFM to your square footage? A good rule of thumb is to double the square footage of your home. For example, if you have 1,000 sq ft, you should look for fans with around 2,000 CFM. Furthermore, if you have high ceilings in your home, you may want to triple your square footage, so a home with 1,000 sq ft and high ceilings would require a fan with a CFM of around 3,000.
2) Climate
Climate is another factor that affects sizing. Humid, lower-elevation climates generally require more airflow (and therefore more powerful fans) than dry, higher-elevation climates. This is because it takes longer for heat to dissipate in humid, low-elevation places whereas arid, high-elevation areas cool off quickly.
3) Insulation Level of Your Home
When a house is well insulated, it will take it longer to heat up. However, once it is heated, cooling off will also take longer and require a more powerful fan. The best way to stay cool is to have good insulation but also keep the house with an attic fan that will keep air circulating in the attic and a whole house fan. This will prevent the heat from building up in the structure of the home.
We have more information on sizing a whole house fan here.