This is my second winter keeping chickens and my first winter not heating. We're expecting lows in the single digits for the next week or so. I've got four chickens in a dry ventilated, uninsulated coop. So far, it's been in the low teens and they've seemed fine. They have a heated waterer outside the coop. Egg production is way down, but the birds seem OK. Anyway, in February, we some times have the odd night at -5F. I am really enjoying not heating and constantly worrying about coop fires. Should I worry? We won't have snow or humidity to speak of. The coop is big enough for 8 comfortably, and if I need to insulate with cardboard on one wall, I can. I just don't know if it's worth the effort. (I'd also prefer they not eat the cardboard.)
Sorry - the chickens are Rhode Island Reds and Easter Eggers. They seem happier in the winter than the summer!