As the guidelines call for a concept which is basic by default and upgradeable by design, I could think of no other more appropriate base material than the disused shipping container. It is rugged and almost non-destructible.
It is modular and thus can be arranged into complex living configurations.
It is upgradeable. Can have solar panels and wind turbines attached in various configurations.
http://youtu.be/dK2AJpKZ7T0
http://youtu.be/JPMxiOFGOFA