Page 24 of the online book below, talks of people up in Canada with -40F temps, keeping their chickens in a open front unheated Wood's coop. HMMM, that's interesting.
Jack
http://archive.org/stream/openairpoultryho00wood#page/24/mode/2up
Jack
http://archive.org/stream/openairpoultryho00wood#page/24/mode/2up