I just built my coop. Being here in Massachusetts it does get cold, and the wife was concerned about the chickens freezing, even though we insulated the coop. I found a very cool product online at Http://CaloriQue.com . It is a flexible film radiant heating panel. They make it for 12", 16" and 24" oc framing. I put 10 panels at 10 watts each, under the roost area, so it is like a 100 watt light bulb except that the heat is spread out over 12.6 sq ft. Highly energy efficient. It hasn't gotten cold enough yet to use, but we're anxious to see how it performs. We did put down cheap ceramic tile for a floor, so we think it should radiate the heat really well.