Apple Crisp, we also get temps that low here in Alberta. Right now it's -17 c, our first cold day of winter! I only have 4 chickens right now, 2 banties and 2 standards. Our coop is small, plus we have a heat lamp. When it's real cold I won't give them the choice whether they want to go outside, instead I provide diversions so they won't peck each other...an apple, oatmeal, a mirror in the coop, etc...You might want to check out the real hardy breeds, although they have lots of different breeds here, and they seem to do fine.
Hoping the best for you! Enjoy your winter!
Tanya