Most of those newer buildings in the Greek islands are built with cement, making them hot whether they reflect sun or not. The traditional old buildings were built with mud and rocks for support, and as I have friends whose families are from the islands I have stayed there, where in 100 degree weather, it was 65 inside. Water was collected from the rain on the roof in underground cisterns, stuff similar to the place I stayed in Grand Junction. All it takes it to use the past in the future with modern techniques, practices and ample technology available today.
We should use non replaceable resources only where necessary, but it takes a lot to educate and persuade the average Joe.