Review on iLiving ILG8SF10VC - 10-inch Wall Mounted Smart Remote Shutter Exhaust Fan with Thermostat, Humidistat, and Variable Speed - Ideal Vent Fan for Attic, Shed, or Garage Ventilation, 820 CFM, 1200 SQF Coverage Area by Adam Gerome

I used two of these in parallel to ventilate a 10x12 greenhouse. The photo was taken before I finished assembling but it gives an idea of the size. Together they let LOTS of air out! Neither of them have internal switches, so you'll need to hook them up to some sort of monitor (unless you want them on all the time). I hooked them up to a microcomputer that turns them on when the temperature goes above 90F and turns them off otherwise. Only criticism is that the felt strips don't touch when the blinds are closed and let in some drafts. Normally this is not a problem, but in winter it can lead to large heat losses. I used plastic on the outside that acts as an "air barrier" to prevent heat loss as much as possible. They were very easy to install, just cut a square hole with a jigsaw and pop them in. I routed electrical wiring outside of the walls.