I've got a double hung window in my coop. In the summer I open the bottom...in the winter months I shut the bottom and open the top part as far as necessary to keep the flow of fresh air into the coop above the birds...this air vents out a opening in the ceiling to vent out the ridge vent that runs the full length of the coop roof... the roof is insulated with eve vents...just like a house.so the warm air rises thru the ceiling vent and out the roof. Creating a air space between the insulated ceiling and the metal roof panels.it cuts down on drafts and keeps the coop dry. The coop walls are also insulated and are vented for air flow to prevent moisture build up...the floor has one inch blue board insulation, plastic vapor barrier, plywood and the floor is covered with rubber roofing that continues four inches up the walls...the rubber does not absorb moisture and helps to keep the coop bedding dry. The used bedding is spread out into the run and turned under with a garden fork...I add a bit of leaf mold and a few bags of peat moss and garden dirt to promote composting. It doesn't freeze hard and the birds help to mix it up by digging for corn and sunflower seeds I give them as scratch.