I'm the same. I think the higher up the windows are though, the more hot air can escape. You also want to leave a windowless spot on the level they roost if it gets cold where you are in winter, so they aren't sleeping in a cold breezy spot. Or plan on covering a couple windows for winter.
Easiest thing might be to buy those circle soffet vent covers and then get a hole saw the right size so you can cut a hole, attach the vent, move down a bit, do it again. But I am not sure if those are considered predator-proof or not?