I like the idea of keeping a red bulb in the coop to keep the air just warm enough to eliminate condensation from chicken respiration. I am in agreement with Rich about not having to heat the coop per se. Everything I've read seems to indicate chickens can handle the cold well, but not the heat of summer. Those hot days we had really stressed our girls this summer. Also, I've read if you get your chickens used to heat in the winter that a power outage will give them a real problem as they will not be able to handle the rapid change to cold.
I think we would like to be warm I'm the winter and transfer that thought to how the chickens would like to feel. Agreed, they would not want to be in sub zero temps, but they do have feathers, and each other to keep themselves warm.
Lots to think about when preparing for bad weather for the first time. I want to increase the ventilation with some vents up by the roof line and maybe insulate the ceiling. The new roof we put on has kept the coop bone dry during this past week of rain, so at least that is one situation that is taken care of.
Still getting 6/6 out of them. One egg yesterday was a monster. We get a fair amount of double yolkers which look as large as two eggs fused together. Had one a few weeks ago that had to hurt coming out. Going to take a look for the pic and post it.