This is an easy upgrade for any home and can be done by a relatively competent DIYer or an HVAC contractor. The main point is that your attic is much hotter than anywhere in the house, so if you can get the attic close to outside ambient, it will help. I personally have my attic fans (one at either end of the house) set up on a separate thermostat from the rest of the house, where any time the attic temp exceeds 90F, the fans kick on.

Doing this will even make your AC system work better if you have one, since you won’t have the extremely hot air in your attic heating your ceilings

This is much less of a good idea than you think:

https://www.energyvanguard.com/blog/75600/The-1-Reason-Power...

A whole house fan is a very different story, but it’s only really useful in some climates.

Yeah I read through that posting and I’m still not convinced that the original poster there is on to much. To add to all of the disagreements in the comments there, I also noticed that my AC works much less hard on hotter days, and noticed a slight reduction in costs monthly electrical costs year of year. There are a lot of variables in play to go into an electrical bill however.

It seems plausible to me that if you have decent air sealing in your house and wildly inadequate ceiling insulation then an attic fan could help. Or if you have poor air sealing but you have enough space for outside air to enter your attic.

In a well-built house, the roof and ceiling shouldn’t be a major source of summer heat gain.

My parents have one and you can feel it all over the house. Works great if a little loud.