A group of New Zealand students have designed the ultimate green addition for eco-friendly living: a "clip-on" Plant Room.
The Plant Room is a small cubic room that bolts to the exterior of a building, allowing extra space for the typical cramped city dweller. The space is intended for gardening, and offers many other green features as well: a rainwater tank, a compost system, and solar power (which heats water for the whole apartment).
The project was designed for the Sustainable Habitat Challenge of 2009. Explanatory video and images below.
For more info, visit the Plant Room website.