I've been looking into a/c alternatives and I had no idea attic fans like that were an option, stoked to have stumbled across this thread!
They're awesome if you can install one.
If you can't, build yourself a fan rack to shove in a window.
https://syonyk.blogspot.com/2015/05/house-fan-for-vertical-windows-diy.htmlI built that for Seattle, when we were renting, didn't have AC, and it was getting unusably hot upstairs. Box fans in the window just make noise if they're fighting ambient wind. This actually exhausted the hot air. I later built an intake downstairs -
https://syonyk.blogspot.com/2015/12/a-post-summer-review-of-my-vent-fans.htmlWhen we moved, we got a manufactured, which doesn't have an attic - so no high flow attic fan. There's a tiny little unit that moves some air, but not enough to be useful. So I just used the same fan rack and we use that to suck air through the house at night.
It's not nearly as nice as a proper attic fan, and I've considered how to increase the airflow (without adding too much noise, ideally), but it works very well and sucking cold air through at night is an awesome way to reduce A/C use. Unless it's really, really hot out (95-100F), I can run the house most of the day without having to kick the AC on if we've sucked cold air through at night.