We are likely to get our first frost this weekend and that leads me to start thinking about winterizing my coop. At what temperature point do you start closing windows on your coops? I have 5 windows at roost height and soffit vents in my 10' x 10' shed with the soffits at 8 feet where the roof overhangs (roof peaks up to 12'). The shed is partially insulated, but will not be heated, I was thinking of waiting until temps get consistently into the 20's at night before I close up most of the windows, and I still want to add some vents near the roof peak. When and how do you start winterizing in northern climates? My birds are hardy breeds and I do want them to acclimate to the colder weather well, since there will be no heat bulb when we hit -30 in February. Thanks!