Those mini-barns need a lot of work, to be made into proper coops. They are too closed up. Get your saw out, and start cutting. First, cut the side walls out between each stud, from where the wall meets the roof, to about 6"s off the floor. Install hardware cloth over the new openings. Then, take the wall sections you just cut and add 1X3" lumber around the inside edges. to stiffen up the panels. Then add hinges to the top of each wall section, and reinstall. During the warmer month, really most of the year, prop open the wall sections, for max fresh air flow/ventilation. Then, cut some big openings, at each end, up by roof peaks. Gotta get some fresh air in there. Depending on the temp, it still may get warm (Hot) in there, but at least the birds will not have stinky stale air to contend with.