I use deep bedding, and I lower my roosts about 6 inches, this pulls them away from the ceiling, and keeps them drier. The ventilation is farther above their heads.
I use black rubber bowls, livestock type, and I have two of them. When it gets below 0, non electrical ideas do not work. However, if it is sunshiny, I will flip the bowl with frozen ice upside down and fill the other bowl. The sunshine absorbed by the black rubber bowl will melt enough that the ice block falls out. If you don't get sunshine, you have to stomp, but that works too.
I set up a sun porch, connecting it to a old black plastic box that I use for shelter in the run. I have three old shower doors, propped up to make an area underneath that the girls can get too. It is often several degrees warmer under there, one can tell by just holding their hand in there.
Also, if I hear of snow coming, I make mini haystacks, then after the snow, I flip the hay from the stack on top of the snow... brings my girls right out. Otherwise they stand in the door, worried that the sky fell in the night.
Mrs K