I lived in a 3rd floor apt. for many years....first of all, heat rises, so the black roof, I feel is a part of the problem, but not the only one..I installed window air conditioners...but only in the living room and bedroom....my apt. was very long, so cross-ventilation was almost impossible..depending on the shape of the apt., window placement, etc., you could see if cross ventilating would be of some help, if he didn't want to invest in a/c units...cross ventilating is when you place a fan, say, in the room furthest away, in a window, with the fan blowing out...then the other fan is placed as opposite from that fan as possible, blowing in....this creates a cross draft..only disadvantage is, the room where the fan is blowing out will not be as cool..ALSO you can just use the 'blowing out' fan in one room and open the window/s in the furtherst room, and that would also move the air... it's really hard to explain!! but I hope it gives you an idea of what I'm trying to say!!! or he could get an a/c unit for, say, his bedroom and use the c/v and fans for the other rooms.......good luck!!