I have read that the “cozy flat screen“ heaters are super safe for chickens warm if needed, they can be put right into the coop. I have bantam Cochins and silkies. We wrap our run in clear greenhouse plastic. Leave a bit not wrapped for ventilation.Then I fill my coop with tons of straw along with the wood chips under the straw. Probably don’t need to do this , but we also throw a large heavy wool blanket over the coop as well for added warmth (we make sure it doesn’t cover the door area so it doesnt stop them from being able to come out down ramp) , we read how others do this. I figured oh well y not try it , certainly will keep them warmer then if it wasn’t on there lol ! We are getting snow and it’s as low as 32-29 degrees last couple days, and windy chill factor, makes it feel colder. They r doing fine ! They Still want to come out of their run and free range , even though they have their nicely plastic wrapped run lol !