Green building is quite in vogue these days with everyone talking about LEED certification and energy efficiency and renewable building materials. Earthships take green building to extremes. These structures are built predominantly of trash. The outer walls are made of old automobile tires and dirt. The walls are 4 feet thick and weigh several tons each. This make them almost indestructible and gives them tremendous thermal mass which stabilizes the interior temperature. The inner walls are made of dirt and empty cans and bottles.
This gives a unique look to the structure. But beyond that, it is a passive solar design that uses a large south facing glass wall to provide lighting, heat, and a greenhouse to purify greywater.
This building is completely self contained. It collects and purifies rainwater for drinking and washing, then it purifies the greywater to use in flushing toilets and then also processes the blackwater for use in irrigating outside landscaping. All heating and cooling is provided by the sun and thermal mass. All electricity is from a small solar array and wind turbine. Therefore you can build one of these in the middle of nowhere and never pay a single bill to any utility company and generate almost no environmental footprint other than the trash you removed from a landfill to build the structure.
I want one.