On the many threads about heating/ not heating a coop, some people who used 250w heat lamps said "I use a heat lamp, does that count?" I thought some folks might be interested to know how using a 250w heat lamp for 3 hours affected the temperature in my coop today. Today's high was around 15°F, and cloudy. Tonight it is supposed to be -3°F. My coop has south windows for passive-solar heating, so if it is cloudy during the day, followed by a cold night, the coop gets quite cold. My coldest night so far was 14°F in the coop when it was -9°F outside the coop. I think we might have gotten a little frost-nip that night. This afternoon around 3pm, I turned on the infrared 250w heat lamp. It was then 8°F outside, and 23°F inside the coop. I left the lamp on for about 3 hours. When I turned the lamp off, it was 36°F inside the coop, and 6°F outside. Starting from 36°F, my coop will probably get down to around 18-20°F tonight. VERY comfortable for the gals in their chicken-down coats. So, on cloudy days with a cold night ahead (0°F to -10°F), I'll try this type of "warm it up" approach with the heat lamp. I have yet to figure out my strategy for -25°F. * If I had 25 chickens, I have been 100% convinced that I would not heat the coop at all, even at -25°F. With 4 chickens, it is a different story. If you have 25 chickens, it is like having a built-in 400 watt heater in your coop. That's about how much heat 25 chickens put out. 4 chickens put out about 60 watts. I'd love to get an additional 340 watts worth of chicken heaters (I want...Chanteclers, Partridge Rocks, Silkies, Speckled Sussex, SLW... I have a list!!! 21 more chickens, no problem!), but unfortunately the tight urban setting does not permit this approach.