When I first started in the trade, I used to advise customers with hot attics to install powered attic ventilators (PAVs) to “suck” that hot air out of the attic. It just made sense to me at the time; if the attic is hot, get the hot out!

When I started learning more about design, someone enlightened me that when you blow air into a space, the same amount has to go out, and when you suck air out of a space (like an attic), it has to come from somewhere. Ideally, the air would come from soffit or gable vents, but in most houses, there are also many gaps from the attic into the home, and a lot of that air will come from the inside and waste energy.

Nowadays, I'm a “fan” (pun intended) of either encapsulating and conditioning the attic or using large, well-vented soffits (will often require baffles to keep the insulation out) and ridge vents.

My friend Neil Comparetto just made a video on this topic that illustrates it nicely: