Use Attic Ventilation Fan When Second Floor Is Hot

Dear Carl:

My brother has central A/C in his 2-story house, but the second floor is so hot in the summer that he had to install a window A/C unit in his bedroom in order to sleep at night. How can he diagnose and correct the problem? Does he need an attic fan? (The attic is not livable space.) Does he need better attic insulation?

His house was poorly built 17 years ago, and he has had many problems with
it. He fixed most of the problems as he discovered them, but he is not sure
how to proceed with this one. (Note: He has a first floor master bedroom
where the temperature is OK, but he moved upstairs when he had a child so
that the whole family would sleep on one level.)



Hi Curt,
Your brother’s problem is an all too common one.

1. Yes, install an attic fan. An attic fan (not to be confused with a whole house fan) will draw heat out of the attic and lessen the radiant heat effect in the upstairs. It is a must for me in all houses. It also has the benefit of removing moisture.

2. Be sure the attic and the roof are well ventilated too. Read my article “Roof & Attic Ventilation is Important".

3. As for attic insulation, increase it as much as you can. Not only will the 2nd floor stay cooler in the summer, added insulation will help save energy in the winter too. The attic is the most important area to insulate well no matter where you live, no matter what your climate is. Read my article “Attic Insulation”.

4. In my article “Home Cooling and Saving Energy” I discuss how to balance the cooling in an HVAC system in a 2 story house. Balancing the system, along with added insulation and an attic fan may solve your brother’s problem in a relatively inexpensive way.

Thanks for writing,
Carl Heldmann,