My chickens are in Norco, and I don't have a "coop" per se. Mine are in chain link runs. Key for my birds as far as keeping cool in the summer is keeping the sun from hitting the dirt in their pens, or at least a large part of their pen during the hotter months. I try to block the sun as much as possible, completely on the south side, full roof and completely open on the north side. Ditto the wetting of the dirt, keeping it loose enough for them to fluff around in and even though it may seem like overkill, you can buy the metal parts at the swapmeet to make a tarp cover like what they have at swap meets. The pipe you buy at steel supplies. For pretty cheap you can make a frame and put one of those heavy duty tarps on it with those loop shaped bungies with a ball on one end, shiny side up. THAT really cools them off during the summer. The tarp does not last two years and has to be replaced every year, but it makes a HUGE difference. That is what I have over my lovebirds and it has made a world of difference for them. On really hot days I will run the sprinkler so it wets down the tarp even and they are many degrees cooler because of it under there.