Hello, This is my first year raising chickens, and my first year having them over the winter. I converted a wooden dog house into a chicken coop. Their water access is always outside the coop as there really isn't any room for it inside. Plus, I just don't want any water in there to keep it from getting wet. Because of this, I'd like them to have outside access most of the time. But that means I'd have to leave the door open. The biggest issue is the door faces north. There's no way to move it. So the cold north winds will blow into the coop with the door open. I still have the clear plastic flaps from when the dogs used the house and was wondering if the chickens would figure out how to use them. I'm also a bit worried about whether or not the chickens will stay warm enough. I only have 4 chickens (2 Barred rocks, 1 Brahma and 1 orpington mix). The coop is fully insulated on the sides, bottom and roof in addition to the pine shavings and straw on the bottom. The nesting boxes are not insulated. I'd say there's about 6-8 square feet with about a 2.5 ft height to it. I don't feel comfortable putting in a heat source. Will the chickens stay warm enough or should I get some more chickens for some more body heat? I live in northern Illinois.