We'll see how mine do tonight - predicted low of -29 (How about you, Mrs. K, expecting something similar?). I gave both coops a nice, deep layer of fresh straw to dig around in today, shut the windows and pop doors. While I was out today, (-5*) I left the people door of one coop open while I was feeding, watering and putting down bedding. The chickens in that coop all huddled in the sunshine that was let in by the open door. I left it for most of the day so they could enjoy the sunlight. I do have windows on that side of the coop, but they don't let in as much sunlight as the door does.
Only getting 2-3 eggs a day from my 15 pullets, but I don't think I'm going to mess with lights in the coop at this point. I figure by the time I get them up to the required amount of light needed to produce eggs, they'll start laying naturally anyway.
I am hoping to have hoop runs for them next year so I can put plastic over them and the chickens can maybe enjoy some greenhouse effect heat on the super cold days like today. We'll see how that goes.