Thank you for your response! I live in Western Washington outside of Seattle, the climate is mild in general with pops of cold (teens-20's) or hot (80's and rare 90s) with the seasons, but mostly somewhere in the middle...generally 40-50's and damp in the darker months, pleasant in the lighter ones.
Certainly something to consider that the hens might be feeling stuffy. The 'window' coverings are perforated so there's a small amount of airflow going through those...perhaps that's not quite enough with the holes along the walls and spaces in the door! I'll look into making that adjustment too.