Since this is our first winter with chickens, I have decided to try what so many call an old time coop insulation. You start with putting down pine shavings and fresh hay. About every 3 days, you use a pitch fork and turn the mixture on the floor. Then you add fresh hay on top of that. They say it will make an excellent compost for the garden.
We are, of course, going to try this. I will let you know through the winter how this works.