Hello All, I finally was able to get a couple acres out in the country and am excited about starting my new chicken flock and get back to my country roots. Anyway, I am building a new coop and had a question about ventilation. I will be housing 15-25 large breed birds in a 12Wx12Lx8H coop I am building. Until recently I hadn't thought much about ventilation, but I've recently had some concerns about it since I will be making this coop very well insulated and draft proof for the cold Michigan weather here, and I will not be heating it other than a maybe a small heat lamp or 2. I am only planning for 1 window for the moment. Anyone know from experience if it will it be enough ventilation for me to just keep the window cracked during the winter or should I plan for more robust ventilation system? During the summer they will be free ranging so I'm not as worried about warmer months. Just the cold/snowy winter months where they will be locked up more often. I've been looking on forums, but haven't found anything yet that addresses my concerns about my particular situation. Most forums answer these questions for either warmer climates where insulation isn't needed or different sized flocks or coops. Any advice from fellow cold-weather chicken owners would be very helpful. Thanks in advance!!!