I learned the hard way this past winter and had frost bite issues on combs. I have a small coop with 2 windows on the front side, and two small opening windows on the back. The chickens roost bar is directly in front of one of the larger front windows. Well, I was closing the small window behind them and the one in front of them, leaving the other two on the other side of the coop open, and had TONS of frost bite cases.
So, I decided to open everything. Even the one in front of them. I did however put cardboard in the window they roosted in front of with only a small slit at the top of the cardboard so that the moisture from their breath could escape. The one behind them left wide open to let the moisture from the poop escape.
NO Frostbite!! I was afraid I was going to freeze my chickens to death, being that it got down into the minus 4 and minus 5 range quite frequently. And ALL the windows of the coop were open!!! But everybody did extremely well, did not get cold and no more frost bitten combs!
So keep the air moving!! Chickens do a LOT of breathing and pooping. And all this exhaling and pooping causes a TON of moisture. Even at 32 degrees, they say a chicken will get frost bite on the comb if there is enough moisture present. And don't worry about it being so airy in the coop. As long as no wind is blowing directly on them, they can take the cold air around them.
So open those windows folks!!!!