The picture shown has the roof of the bus showing. I would think it would be hotter inside. If I were doing that, I would seal it with a cool seal roof treatment and then put as much dirt as I thought the roof would hold up. Oh, and put a heat barrier like what goes under tin roofs, but put it on the inside of the bus roof. What are your ideas? And do you have access to an old bus or shipping container?I really like using an old school bus as a root cellar. Totally awesome!!!