Attic fans were a popular item in homes built in mid-20th century. Builders believed that they helped to create a good airflow in your attic which would help keep it cooler and reduce the heat load on your home. Many of our homes today still have these fans installed. If you have one, should you use it? If you don’t, should you install an attic fan?
The Biggest Problem with Attic Fans
Attic fans operate on the premise that they draw in outside air and help pull it through the attic. But, more often than not, the negative air pressure in the attic draws conditioned air from the living space. This will achieve the purpose of cooling the attic, but at a great expense. Ceilings and attic hatches are not airtight. The attic fan will pull air from the living space into the attic. Air in your living space was expensive to cool down so letting it flow into the attic is a waste.
On top of that, attic fans require energy to operate. It’s not a lot of energy, but it’s still a constant drain when the temperature is above a certain target. So to add insult to injury, you have two sources of waste occurring when your attic fan operates.
Should I install an attic fan?
Only if you enjoy paying more on your energy bill, operating an inefficient home and making your air conditioner work harder than it needs to.
What should I do instead?
The best ventilation occurs naturally through an adequate amount of soffit and ridge vents. Warm air builds up along the underside of the roof decking and naturally flows up to the ridge. Soffit vents serve as an intake to replace the air that exits the ridge vents. This creates a circular flow of air effectively washing the underside of the roof decking with dry, cool air, creating the ideal attic air conditions – and no powered fans are needed.
I’m not sure if my ventilation is working or not.
You can do a few things on your own. First, check to make sure you have baffles in your attic to keep air flowing from the soffit to the ridge. If you don’t, you can add them. Also, check the nail holes from the shingles. If there are dark halos around the nail protrusions, that means moisture is building up where it shouldn’t and your attic has insufficient airflow. We’d love to come check it out for you and give you our opinion. You can visit our estimates page to schedule an appointment or call us at 888-776-1998 today.
2 replies on “Attic Fans: Good or Bad?”
Been telling and explaining to clients for YEARS how an attic fan operates and its air pathway! It is all a matter of physics. I have even checked there efficiency with an attic thermometer. The reduction was ONE degree!!!
If it were it possible for the homeowner to ‘see’ the air, things would be obvious!
Glad to see I have your concurrence.
Only people profiting are the Electrical companies/stockholders.
Why would anyone run an air conditioner and attic fan at the same time? I have used my attic fan my entire life in the fall and spring and it makes my home very comfotable but never with heat or a/c on, that’s just idiotic. The motor just wore out after 65 years and I intend to replace the motor asap since nights are cool enough to use it.