Probably depends on your situation.
We have NO shade at all and in the heat of summer here in TX, there is often no wind when it's really hot. It can still be 90-100* at 10 pm. We used styrofoam insulating boards coupled with tile board for the inside walls of the coops. It helps keep the coops anywhere from 5-10 degrees cooler than outside. Which means when it's 110* outside, it's probably 102* inside. But it really has helped with keeping a little cooler despite a lack of shade, and when it is too hot, the chickens will stay inside rather than go outside even though they have artificial shade over their runs.
The roofs are peaked so that air can enter under the eaves and escape out the top - like regular housing construction - in addition to windows and vents at floor level too.
It can be freezing cold with blowing snow and rain and our chickens would rather be out in that, rather than the heat of summer.
Sounds like we have similar weather, except that it is a rare day the air isn't moving, and often it moves faster than I would like it to. We are just east of the mountains, and we get wind of some variation almost every day.
Question - what is tile board?