The window is meant to be that way. Dr. Woods explains how the placement of the windows keeps air flowing through the coop so there is no moisture buildup and the litter stays dry. It does work very well. We did modify the side screen windows so we could put in some stationery windows for snow storms or hurricanes and dh hung some on the upper screened windows, again to be closed only during severe storms. It does stay dry in front, despite the windows. These types of coops were used in the east coast by many chicken farmers, large and small. There is a book you can get that Dr Woods wrote about them. Our coop is on the small side for such a design and yes, we used that smoke roof for natural light and passive heating from the sun. The most important thing that everyone on this forum will tell you is ventilation in your coop. Chickens can survive cold temps very well. Its moisture in the coop, whether from them breathing or pooping or leaks that will cause all kinds of issues for them.