I have two windows in their coop that let sunshine in. They dont leek cold air and i made sure of that. We have tin over part of their run. We are going to get clear tin to go over the rest of it. And they have alot of extra bedding.I add an extra layer of shavings on the floor for the chickens in this cold weather, then sprinkle some boss on it to keep them busy. I think the activity helps keep their feet warm. They still like to go outside in the sunshine - but this flock only goes out when I have shoveled their run. They don't do snow!