I built it my way, cavity wall filled by 1.5 inch rigid foam between walls that get sun. I wanted to build cavity walls by red bricks, but the type was not available in my area. Walls remain cool with sunlight over (also it blocks noise with my type of windows, no sliding). I installed an exhaust fan for under the roof that works with a thermostat (manual control too). It kicks when it go over 40 degree, it it reaches that hot since I used insulated metal roof.