Definitely leave the glass open for fresh air. We were just cautioning that you'll need hardware cloth. Inside or outside doesn't matter as long as you can still operate the window. Just put some trim on the edges of the hardware cloth so they can't pry at the edges. Hawks and owls are observant and smart. If they find out where prey live, they can find a way in. I use a little piece of flashing and fashion an awning over windows in buildings without a roof overhang to keep water out so I can leave the windows open. Nothing like some Rory to get one fired up in the mornin' or any time. If Whites is old as dirt, maybe I'm sand then.