We have completed our second coop. It is a 12 x 16 (I think that's right) wooden storage building that we converted. We have yet to add a pop door and the screened doors on the front. We had decided to outfit the front with two screened doors, one that can be opened, one stationary. This will give the coop maximum airflow during our hot summers. The screen in the doors will be replaced with hardware cloth. The two solid doors on the front can be closed during really bad weather. For some reason DH is very reluctant to cut a pop door in the sidewall of the coop. Instead he wants to make a pop door in the bottom half of one of the screened doors (the stationary one). We've already figured out how to do that. If we go with his idea, it would require that the solid door on that side be kept open all day long, to allow access to the pop door for hens going into the coop to lay. Of course it can be closed at night. I'm concerned about all the cold air that's going to get in the coop during the day by that door being left open. Once it's closed up in the evenings the coop will be pretty tight, with only the ventilation holes near the roofline. My birds free range all day so except for egglaying only make use of their coop at night. Our winter lows can get in the teens, rarely lower. Do you see the solid door being left open during the day to be a problem?