We live in North Dakota, and heating the coop is a waste. It is -10 outside right now, and about 19-20 degrees in my coop. My ladies are fine. A couple even ran outside for a little bit, but for the most part they are just hanging out on their roosts. I have a draft free, un-insulated shed that I converted into a coop. I don't even have a coop door. Don't be afraid of the cold. Your chickens will be fine.... just ask the sparrows sitting on my fence with no fancy coop hotel to call home lol. Oh, I also use the deep litter method for my coop in the winter. Works well and insulates the floor nicely.