Keeps it cooler in the summer and warmer in the winter, but you have to fill the space with some kind of insulating material that the mice don't like to nest in to get the best effect. Depends how much work you want to do. My coop has to survive winters to 50 below, so it's insulated, with a couple of quadruple paned windows for light and vented eves and pop door. Works great, but it was a lot of work. I lined the walss with 2" thick foam panels, cut to size from 4x8' sheets, and plywood back over that.
Pity the poor mouse that tries to go into that coop! Hens will get it for sure.
Pity the poor mouse that tries to go into that coop! Hens will get it for sure.