Hi! You're getting good advice here. Ventilation and predator-proofing are the keys. I'm in NC, and my girls don't spend any time in the coop/run except for roosting at night and laying. My coop has three inch openings all around the top, covered in hardware cloth. When I do my next coop (next month), I'm going to make two walls framed hardware cloth. Heat and humidity are much more an issue for me than cold, though it does usually freeze a few days a year. So far, no troubles.
Also, I got several rolls of HW cloth at tractor supply when they had a 'neighbors club' discount. Five rolls of 25' four foot cloth cost $75. They do it a couple of times a year. Good for you for taking the time to design and accumulate what you need!