My coop is 4' d x 3' w we had done a window in the front that is 30" x 10". I had originally placed acrylic over it for the winter last month- but after reading about the open air coop designs I realized I didn't have any ventilation and needed to add some. I know I don't have the same design as the open air coop but I think that it should still work well by not creating a draft and allowing them to have fresh air and let the stale air leave since the window is in the highest part of the coop. I was reluctant since I feared they would be cold- but in researching I think it is probably the best thing I can do for my girls.