Edwin Pawlowski wrote:
Ideal is both.

If you have no AC, go with the whole house fan. The advantage is that it
will draw in cooler air from outside and push the hot air out of the attic.
The disadvantage is that on a very hot day, it will draw in the hot outside
air and replace what may be cooler inside. That is when the power vent in
the attic is best.

If you do add AC, you don't want to use a while house fan at the same time.

Ditto that, but using the fan for double-duty. In my case, during the
day the power vent fan in the attic switches on around 100 deg. F, with
the attic sealed off from below. When temps drop outside in the
evening, I open some windows at the (N) side of the house, farthest
from the door to the attic, and open that door, then drop the setting
on the fan t-stat. Soon, I'll just put in a manual switch in parallel
with the t-stat, or a timer.

J