The home is green not just because of its minimal footprint: it is designed with passive solar design, a highly insulated building envelope, ground source heat pump, and rainwater harvesting for flushing toilets and watering the landscaping.
There's a great video of Tozer doing a walk-through of the house at Sprig's How to Build a Smart (and Very Skinny) Green House. See more of the Gap House and other work at Pitman Tozer Architects. And get even more in-depth info at the project's blog, architect's self-build eco house.
Images: Nick Kane