This is our first winter with chickens and I'm proud to say that they did fine over a subzero weekend with the lowest temp being -24 (not counting windchill). We have an insulated coop based on the Wichita Cabin coop. It's 4x5 inside with 6 hens - barred rock, rhode island red, and buff orpington. We put plastic around the run, similar to what the Wichita folks did. Our coop is very exposed to the elements in windy SD - no trees. We covered the two main ventilation openings and took our ADOR1 door out of automatic mode. We kept them in the coop for the weekend, just replacing their water twice a day as it would freeze. We had no supplemental heat and they did just fine. Today's in the single digits and they are very happy to finally be out in the enclosed run again.