We have four chickens that are 28 weeks old now. We got them when they were a day old on May 6th. We have a Black Australorp (Muffin), Buff Orpington (Nugget), Silver Laced Wyandotte (Oreo), and an Americauna (Peanut). We constructed a roughly 4x4 coop. It was constructed with typical lumber and plywood, with insulation and then paneling for walls. There is also siding on the outside. (Pretty well insulated!) We live in Wisconsin where it can get down right cold during the winter. Right now, our lows are around 15F and highs around 35F. During the dead of winter, it gets into the negatives, sometimes having highs in the single digits. We clean the coop weekly- taking out everything and starting fresh. We purchased a "650 watt panel heater" from Fleet Farm a few weeks ago. (I know it's a little overkill for wattage, but was a great deal- half the price of a 250 watt panel. Also thinking it wont be on too long since it will heat the coop fast and won't have to fight the cold weather.) We have it on the ceiling inside the coop. It is on a thermostatically controlled outlet that kicks on once it's below 38F and back off once it hits 50F. There have only been about 4-5 nights that it has actually turned on so far. Thoughts for that was that it will keep the water from freezing and eventually keep the eggs from freezing. We have two chickens with regular combs and two with pea combs. I don't want to chance frostbite or my little girls being cold! We clean the coop weekly and actually use the air compressor to blow the dust off the heater. A lot of people use them in a house and they are not a fire hazard if they are dusty but we "dust" it weekly just to be safe. My thought is that since it's on the ceiling, it shouldn't be a fire hazard because its not near the bedding or anything and can't "burst" or be bumped by the chickens like a heat lamp. Today it is 30F outside. I opened their chicken door up about an hour ago and they gladly went outside. I don't want them to become to acclimated to the "heat" that going outside would be detrimental because they don't have good coats. They are all cold hardy breeds and I'd like to offer them the chance to go outside on sunny winter days. The coop is on the east side of our garage so it gets the morning sun which warms it to 40-50F almost every morning (granted its been around 30 at night). There is also a wind block on the north side of it (we have a very large rack of wood that will block 75% of the northern weather). Is it worth keeping the heater in there? My thoughts are maybe getting a thermostat that keeps it a lil cooler like between 35-45?