pen,
1. You could start adding some early morning light now. On a timer. This would add plenty of light to keep egg laying going through winter. You might want to have it snap off at 5 pm so you don't catch them unaware.
2. Chickens need time to adjust to cold, but adjust they do. They'll do better in cold than in severe heat. Much better. No added heat is necessary whatsoever, IF you have hardy breeds. Dry at all times. Good wide roosting bars and they'll be just fine.
3. You could begin to shut a window or all the windows if you have good ventilation out the roof or at the roof line. Noxious gasses must still escape as must the humidity. You cannot seal them up tight or the humidity will be brutal, the gasses toxic and the risk of frostbite in really cold weather too high. Frostbite is primarily caused by the humidity "frosting" or condensing, not merely the cold temps by themselves.
