Like the other posters mentioned, it depends on the location, climate and integrity of the neighborhood.
My current KH in the main auditorium, about 20 windows. There are about 10 on each opposing wall.
My former KH had no windows.
My KH before that had 4 long rectangular windows located at the top of the wall. Two on each side. As the ceiling was about 15 feet above the floor with these windows just below them, you couldn't peer out of them.
Alligator Wisdom (aka Brother NOT Exerting Vigorously)