My project fits the Lifecycle Building Challenge so well that I'm considering getting my plan in presentation-quality text and pictures in time to submit it!  In so many ways, it's a sequence of re-use.

• I was born in the house that stands now and the parents are still there.
• I'll be re-using materials from the garage, and re-using 3+ shipping containers.
• The lot is being re-purposed, with minimal change in footprint.
• When I'm ready to move, the top story can be taken with me if I choose to use elsewhere.
• Another container can be added at the back of the remaining structure, so that my aging parents can live in it on the ground floor and sell/rent the main house.

Basically, it's a design that adapts to the family on the lot growing up.  A similar plan could work for other families, and both halves (the "parent" and "child") can be stacked to increase density without consuming more land.  My project's scenario is more dense than the starting point (one old house on the property), but the full cycle is not truly sustainable with a growing population unless new units are placed on top of the previous ones. 

 That's partly because population growth isn't completely sustainable, truth be told.