I live in Wisconsin. We insulate the coop in the late fall by collecting newspaper and crumbling them up and filling all the vents up with newspaper. For the rest of the year, there is 1" styrofoam board between the outside wood and the inside on most of the walls. We tried various things to insulate the ceiling, but the it became a place of mice to live. Now, we just go with the newspaper and then burn it all each spring. The coop used to stay about 20 degrees warmer than the outside temperature. This year, we but an addition on it that is cement block. We are hoping that works better. We use heated watering bowls made for dogs in the winter or the water would freeze solid. If we are getting temps that are seriously below zero, we have turned on a heat lamp or even a little heater. I'm hoping this year I won't have to do that.