Same here in Minnesota. Close windows, but keep soffit vents open. I also have a ridge vent. For the run, I put up polycarbonate panels so they still get light, but no cold wind. The upper north side of my run is open for ventilation, as well as open ridge and soffit vents. They spend every winter day out in the run, even when the daytime temperature is -25f. Heated waterer is a must.Except for adding a heated waterer I don't do much in winter except close the window that is next to the roost. The 10 square feet of vents I have stay open year round. I live in NW Montana where it gets down in the -20s F.