So I have 15 meat birds outside in a 8x10 dog kennel on a concrete pad, with a fenced yard around the outside. The run is tarped, and there are 2 large dog kennels for sleeping time inside. We just got 5 inches of snow so they are hanging out in their kennel area which I bedded with pine straw since the concrete is so cold. The next few days are supposed to be highs of 20s and lows in the single digits and I was worried they would be too cold at night. Two nights ago I stacked 4 old quilts on top of the kennels, and layered newspaper and shavings inside. Tonight I reached in as they were getting settled for the night, and it's like an oven in there! Those little meaties put out quite a bit of heat. I don't even think I will need any supplemental heat for them, as long as I keep it deeply bedded and dry, and loosely cover the doors of the kennels at night. Just mentioning if anyone is trying to raise meat birds in the winter which, in retrospect, was not a great idea. I've never worried about my hens; we used to live in MA and winters there were much worse than here in VA, and as long as I kept their houses dry and well ventilated, they were fine, even in minus 10F. But it seems that meaties are not as cold hardy, despite feeling like little hot potatoes when I pick them up.