Personally, if those windows aren't on the windward side I'd leave them all the way open, but I'm a massive proponent of fresh air in coops and don't have more than three walls on any of mine.
Entry 2
I wasn't finished building this coop when the weather decided to get in the way. The snow kept the inside nice and cozy, even without a tarp. I have to thank BYC for introducing me to the concept of hoop coops - they're great!