My old apartment was built this way, except it was to share cooling because we lived in a very hot area. I think the insulation or whatever it was supposed to be, was bad because the air conditioning guys were there all summer craning new units onto the top of the buildings. It doesn’t help that nobody would close the breezeway doors and we effectively had a bar of heat running straight through the building. (although maintenance did force the issue right before we left, they removed their ability to stay open.)