I think what you've done is really cool. I like the simplicity, functionality, and originality. Way to go man! It's a little contrived for my style (too much work haha), but like I said, it's great. An admirable invention!
My idea to contribute is that I bet it would work better as a retaining wall like on a tall terrace, or against a cliff, so it could be backfilled up to the wall on the back side and use the earth for temperature and moisture moderation. Perhaps a new way to plant out a cliff side or rock bluff? Does anybody here know of a better way to plant out the side of a cliff? Or would you consider this the ideal solution?
I'll be eager to see more updates on how this thing performs! The gravity feed water tower sounds interesting! How are you planning on harvesting the water and placing it up high in the tower?