Earthships

by Chuck Hall

Way back in the 1970s, architect Mike Reynolds got the crazy idea of building homes out of used tires and beer cans. Shortly afterwards, Earthship Biotecture (www.earthship.org) was formed. The idea for the Earthship is simple enough. It is designed to be a home that exists in perfect harmony with the environment. Ideally, the Earthships generate all of their own utilities. They heat and cool themselves by using passive solar technology and the earth’s thermal properties. They generate their own energy using solar and wind systems, and harvest their own water from rainwater catch systems and cisterns. Sewage is contained and treated at the home site. The earth-covered roof can be used to grow fruits and vegetables, and many Earthships incorporate a greenhouse into the design.

Earthships also recycle materials that would otherwise end up in landfills. The outer walls are made of tires filled with rammed earth. The dirt is hammered into the tires by hand using a sledgehammer. The interior, non-load bearing walls in an Earthship are usually made of aluminum cans. The cans are stacked, honeycomb fashion. Stucco is then applied to the surface of this aluminum-can wall, using the pull-tabs instead of stucco grating to help the plaster to adhere to the surface. Other recycled materials, such as scrap wood from building sites, or old discarded windows and doors, can also be incorporated into an Earthship design.

Earthships take advantage of the solar and thermal properties of the building site in that they are buried into the side of a hill or otherwise covered with earth. Here in the northern hemisphere, they are oriented to be south-facing in order to capture maximum heat and light from the sun. The northern side of the building is incorporated into the hill, using the earth as a natural insulator to regulate the interior temperature both day and night.

Older Earthships had problems with heat loss during the winter months. The south-facing wall of an Earthship is mostly glass, so the heat radiated out during the winter. In newer Earthship designs, this problem has been taken care of by adding an overhand that, due to its angle, shades from the sun in the summer months, but allows the sun to enter during the winter months. Also, since Earthships were designed for the rural Southwestern United States, they may have to be extensively redesigned by a qualified architect or engineer in order to function properly in other locations. Finally, Earthships generally perform better if constructed of stone or earth bags. While the idea of using tires to eliminate waste is sound in principle, hammering dirt into tires is a labor-intensive process, and in a truly sustainable world, tires would be recycled as newer tires, not as building materials.

Stuart Simmons of Durango, Colorado, has built an Earthship, and documented his adventure on his Web site. If you’re interested in learning more about Earthships, I’d highly recommend his site: www.earthships.com.