and this may help you when someone asks "won't your chickens be cold"?
Its the book on "Woods' Coop" (the person, not the place) design, which is a partially open air coop design for the upper US, also used in Alaska and Canada. Nearly 100 years old. No heat, no fans. Just physics.
Agree with Sally - you want LOTS more ventilation to help enusre moist, ammonia laden air is moving out - in ways that don't result in a draft on your birds.
Yes, if you have power, you can use an exhaust fan - make sure you get one suited for the environment - all that feather, dust, dander...