You beat me to it. Years ago I had a great aunt and uncle that a very large chicken house much like the one in your photo. If I had to take a guess I would say it was 25 feet long by 15 feet wide or so ( I wish I had a photo of it) . It was much larger than the average persons coop as they sold eggs from their front door and to the local grocery stores. They probably had 150 birds or so.
The larger side was the side with the nest boxes and hanging feeders and the smaller side was were the roosts were. The roost portion of the coop was completely open on the south side. It had a hardware cloth type covering. I just got off the phone with my dad just to double check and he and I never remember them putting any type of cover over the opening.
They raised leghorns a skinny large combed breed.
My grandfathers chicken houses were 40x80 and there was 4 of them, I guess heating them would of been impossible...