So far this winter I have yet to add a heat lamp in the coop for my layer flock. At times it's been as cold as -15F overnight but the girls have been just fine. In preparation for super cold snaps I'd like to put a heat lamp in the coop that I could turn on when needed (like -20F or so). My question is where do you think is the best place to put it? Should I put it over the roosts or elsewhere in the coop like over an open floor space area? Thanks!