Ok, so this is my 1st winter in NJ with chickens. I have a pretty tight coop and they are either pastured or free range during the day. I did build them a small plastic covered hoop house and filled it with straw. It can get a little warmer than ambient temp. They dont like the crackling of the plastic though when it is windy, though I have noticed them using it more so I guess they are getting used to it. I throw scratch in there as well.
I dont add heat, I decided to trust that if people in N Dakota dont add heat, NJ chickens would be ok. I did insulate the walls and did add plastic to the roof rafters to cut the ventilation a little (no direct breeze on them).
Most days they have come outside and huddle next to the house (southern side against my brick house--I put straw there too). It is currently 1 degree out. I have noticed that in the morning when I open the pop door, it is a bit warmer in the coop than outside. I think that by opening the pop door, I end up cooling the coop. Today they were not even off the roosts. I put their water inside and closed the coop back up. I guess if they seem restless later, I will open them up.
Is there a way to not lose heat with a pop door? I do have a feed bag partially across the door on the inside.
My rooster has a few spots of frost bite on the tips of his comb, but other than that, the chickens are ok. But, darn...I feel bad for them. I am so tempted to take the oil filled space heater in there just to give them a little relief....