Architect Michael Reynolds launched the Earthship concept in the late 1960s. After moving to Taos, NM, Reynolds used items like cans, bottles and tires to create organic structures that seemed to grow out of their surroundings. Many Earthships can provide and manage their inhabitants' water, heat, electricity and sewage needs without being connected to outside utilities. These "spaceships on earth" quickly grew in popularity, and Earthship communities, as well as houses sporting Earthship-like features, have been built around the globe [source: Freed].
While most Earthship designs are adapted to the local climate, available materials and user's needs, they often share a number of features. The walls are commonly constructed using old tires packed with dirt, stacked like bricks and covered in an earthen material to make smooth, organically flowing walls. This technique creates walls up to 30 inches (76 centimeters) thick -- a wonderful insulation system that keeps heating and cooling costs extremely low [source: Earthship Biotecture].
Earthships often include passive solar features, such as greenhouses, skylights and windows arranged to make the most of sunlight for light and heating. Using solar arrays, solar heat and geothermal heating, these dwellings can often maintain the desired temperature without outside power.
The Earthship concept extends beyond the home, as well, with organic gardens, composting and rainwater collection. Between the cost savings of this energy efficiency and the low cost of construction, Earthships may provide some of the biggest ecological "bang for the buck" in green homes [source: Earthship Biotecture].