It has been 9 degrees here the last few days..........The coop has a couple of heat lamps and is wind resistant.....I have read more about wind versus warmth.....((??))) I don't want to start a war about this, but it is what we built for our first coop.........THe chickens are still alive and laying eggs..!!! I also used the clear sheets of plexi so I could see thru the coop into our horse pasture from the barn.........We bed really thick shavings to help with warmth if the chickens want to burrow into the shavings. You can insulate the walls if you feel your part of the country warrants. I am in Southern INdiana and have such a range........This is our first winter with birds and if they all survive this cold winter, I probably will not insulate my coop.........Good Luck