Here the walls are complete. The double wall was necessary for strength. My decision was whether or not to insulate them. I quandered this for some time. On the one hand I want rapid temperature equilibrium at night but, on the other hand I don't want the interior to get very hot during a sunny day. The first indicates poor insulation, the second indicates good insulation. I decided on good insulation together with plenty of ventilation. So the walls are insulated, and the roof will be too.
You will notice no window. I see no point in one.