In our yard we have both a permanent coop and a chicken tractor that I move around the yard. In cold climates, just having a chicken tractor wouldn't be sufficient enough protection and insulation for the birds during the winter. Our permanent coop, on the other hand, is insulated and in an area of our yard that is quite protected. I find I am only adding supplemental heat to the coop for the few days every winter when it dips below -20 degrees. Conscious of zoning in permaculture (i.e. putting things that need your daily attention closer to the house), I also placed the permanent coop roughly 50 feet from the backdoor for ease of feeding them every day. When you're making a trip out to the coop twice a day in the snow, you want to make that journey as short as possible!
Having this tractor allows me to pick and choose the areas of my annual garden beds where my chickens can scratch up and fertilize. I use the tractor in the spring and fall in my annual garden beds and place it in other areas of the yard during the summer. Check out my video below where you can see the tractor (and chickens) in action!