Ah so you get snow, sometimes strong winds and cold temps.
Vents up high to keep moisture from building up will help prevent frostbite. I made mine closable so whichever way the wind is coming from I can close that side and open the other.
I even have leghorn with only ever one very mild case...
I keep large and small birds.
Brahma to bantam Cochin's make it just fine here with no added heat. I do use a bucket heater for their water.
We get weeks where we do not get above zero for the high. Mine choose to stay in when it gets like that so I end up cleaning the coop more.
Listing what...