I'd like to hear more about your setup Pandora...
We were the coldest next to Siberia here on Sunday at -46 Celcius, Edmonton area and my poor chickens (mainly the Roos) have frost bite. The Barred Rock girls and my NH Red girl are fine, but the boys and the Silver gray Dorkings look awful! We ended up putting a heater in the coop, it is mostly insulated with the roof area boarded up ( they like to roost on the rafters, but the area was too large to keep heated, and the roof isn't insulated yet) but it didn't warm the coop that much. I have eaves ventilation and we stuffed full of straw to act as insulation but not block the vent completely, no condensation on the windows at all so I am happy about that. Deep litter method with straw on the insulated floors.
So today was a beautiful day with a high of 2 celcius. talk about extreme weather changes. The chickens and the goats were all hanging out in the sun. the chickens and the goats free range, but the chickens hadn't been out for weeks, i was amazed that the goats fared better than the chickens and they didn't get heaters...or insulation.