Here are some thoughts:
#1) Build a tall coop. Let the hot air rise away from your birds, and out through ventilation. Let's say the coop was going to be 8x10' for example. You could build a modified flat roof design, with some roof pitch to let rain run off. One wall could be 10' tall, and the opposing wall could be, say, 8' tall. Or...even 10' and 12'. On the tall wall, you could place some some fully openable windows. They could be rectangular windows oriented horizontally. They could be placed high, and when swung open, could hook onto the roof eave.
If you don't like the looks of a flat roof design, you could have a conventional roof hip with a roof vent on top.
#2) Consider no windows on the south side, where the sun beats in. Ditto for the evening sun on the west side. Perhaps just a north and east window.