I apologize for the late update--sorry :( This is about Earthships.
Earthships are environmentally friendly houses, built out of recycled materials. Each house is made of tires packed solid with dirt, and staggered like bricks to form walls. The walls are load bearing and provide thermal mass, which stores heat and releases it slowly, so that the indoor temperature stays the same.
Earthships are designed to use available natural resoucres. Rainwater is stored, and gray water (relatively clean waste water from baths, washing machines, e.t.c.) is recycled. Solar energy is also taken advantage of, and is stored for later use.
Sorry again, this time for the hasty post!