Bob F wrote:
HeyBub wrote:
Big Jim wrote:
If you want ventilation get a fan. More insulation is always good



The problem with a fan is that it must exhaust massive amounts of air
to be effective. Assuming an 1800 sq ft house with a 6' attic at the
peak, we're talking (roughly) 6 x 1800 x 0.5 = 5,400 cu ft. An attic
exhaust fan should change the air every 2 minutes, so you'll need a
fan that moves 2,700 cu ft of air per minute. That's a good sized
fan.

Why on earth does a fan have to change the air every 2 minutes to be
helpful?

Because if the area is being heated faster than you can remove the heat, you
don't accomplish anything.

I don't know that 2 minutes is the optimum value - it may be one air
exchange every half-hour or it may be twice per minute. I'm sure somebody
has figured it out. Research is called for.