What Is An Earthship?

Earthships are earth-sheltered autonomous buildings made of tires rammed with earth, which are usually arranged in "U" or horseshoe shaped modules. Windows on the sunny side admit light and heat. The open end of the "U" shaped structure faces South in the northern hemisphere, and North in the southern hemisphere, so that the house will catch maximum sunlight in the colder months. An Earthship is designed to interface with its environment wherever possible and create its own utilities.

The Earthship, as it exists today, began to take shape in the 1970s. Michael Reynolds, founder of Earthship Biotecture, a company that specializes in designing and building Earthships, wanted to create a home that would do three things. First, it would be sustainable. It would use material indigenous to the entire planet as well as reuse materials wherever possible. Second, his homes would generate their own utilities and be independent from the "grid" so they would be less susceptible to natural disasters and free from the electrical and water grids that Reynolds considered ugly. Finally, it would be available. He wanted to create a home that the average person with no specialized construction skills would be able to create.

Eventually, his vision took the form of the common U-shaped rammed-earth tire home seen today. However, as a concept, the Earthship is not limited to rammed-earth tires. Any dense material with a potential for thermal mass, such as concrete, adobe, or stone can be used to create an Earthship.

Currently, Earthships are in use in almost every state in the United States , as well as many countries in Europe . The use of insulation on the outside of tire walls, which was not common in early designs, is improving the viability of Earthships in every climate without compromising their durability.

The rammed-earth tire version of the Earthship is now the most common, and is usually the only structure referred to as “Earthship”.

Unlike other materials, tires are more accessible to the average person. Scrap tires are ubiquitous around the world and easy to come by; there are an estimated 2 billion tires throughout the United States. According to the Scrap Tire Management Council, as many as 253 million scrap tires are generated each year in the United States and of those 253 million tires only 53% are reclaimed by the scrap tire market (collector's license needed). In addition to the availability of scrap tires, the method by which they are converted into usable "bricks", is simple and affordable. More....

The rammed-earth tires of an Earthship are usually assembled by teams of two people working together as part of a larger construction team. One member of the two person team shovels dirt, which usually comes from the building site, placing it into the tire one scoop at a time. The second member, who stands on the tire, uses a sledge hammer to pack the dirt in. The second person moves in a circle around the tire to keep the dirt even and avoid warping the tire. All tires in an Earthship are made in place because, when properly made, they weigh as much as 300 pounds and can be very difficult to relocate.

One of the benefits of the rammed-earth tire is its great load-bearing capacity. A fully rammed tire, which is about 2 feet 8 inches wide, is massive enough to surpass conventional requirements for structural load distribution to the earth. Because the tire is so dense, it does not burn when exposed to fire.

Systems

The Earthship was designed as a structure that would exist in harmony with its environment and be freed from the constraints of modern shelters which rely on centralized utilities. It is important that the Earthship create its own utilities as well as use readily available and sustainable materials. In order to be entirely self sufficient the Earthship needs to be able to handle the three systems; Water, Electricity and Climate. While these systems are not exclusive to Earthships, a properly designed Earthship must have these systems.

Water Collection: Earthships are designed to catch and use water from the local environment without bringing in water from a centralized source. Water used in an Earthship is harvested from rain or snow. As water collects on the roof it is channeled through a silt catching device and into a cistern. More....

Water collected in this fashion is called greywater. Although it is unsuitable for drinking, it is used within the Earthship for a multitude of purposes. Before the greywater can be reused, it is channeled through a grease and partical filter/digester and into a 30”-60" deep rubber lined botanical cell. This botanical cell is a miniature living machine. It is also known as constructed wetlands.

The constructed wetlands are an important part of the Earthship concept. All the wastewater (other than the toilet) is drained into these structures and used to grow an indoor garden. Filtration is achieved by passing the water through a mixture of gravel and plant roots.

Due to the nature of plants, oxygen is added to the water as it filters, while nitrogen is removed. Water taken up through the plants and transpired at their tops helps to humidify the air. In the cell, bacteria will naturally grow and help to cleanse the water.

Plumbing drains are fed into the wetlands at one end, the unit sloped away so that water entering will flow downhill being purified along the way. Water from the low end of the botanical cell is then directed through a peat moss filter and collected in a reservoir or well. This reclaimed water is then passed once more through a grey water board and used to flush conventional toilets. At that point the water becomes "black water".

Black water is not reused within the Earthship. Instead, blackwater is sent to a solar-enhanced septic tank that is often called the “incubator”. The solar enhanced septic tank stores the sun's heat in its concrete mass, which is insulated, to help the anaerobic process. Water from the incubator is channeled out to an exterior landscaping planter cell that is similar to the botanical cell used in greywater treatment.

Electricity: Earthships are designed to collect and store their own energy from a variety of sources. The majority of electrical energy is harvested from the sun and wind. Photovoltaic panels and wind mills located on or near the Earthship generate DC energy that is then stored in several types of deep cycle batteries. Additional energy, if required, can be obtained from gasoline powered generators or by integrating with the city grid. More....

Climate: The interior climate of an Earthship is stabilized and made comfortable by taking advantage of many phenomena. Mainly, the Earthship tries to take advantage of the properties of thermal mass and passive solar heating and cooling.

The load bearing walls of an Earthship, which are made from steel-belted tires rammed with earth, serve two purposes. First, they hold up the roof, and second, they provide a dense thermal mass that will soak up heat during the day and radiate heat during the night, keeping the interior climate relatively comfortable all day.

In addition to high thermal mass, some Earthships may be earth sheltered. The benefits of earth sheltering are twofold because it adds to the thermal mass and, if the Earthship is buried deep enough, allows the structure to take advantage of the earth's stable temperature.

The Earthship is designed in such a way that the sun provides heating, ventilation and lighting. To take advantage of the sun, an Earthship (in the northern hemisphere) is positioned so that its southern wall, which is nonstructural and made mostly of glass sheets, faces directly south. This positioning allows for optimum solar exposure.

To allow the sun to heat the mass of the Earthship, the southern wall is angled so that it is perpendicular to light from the winter sun. This allows for maximum exposure in the winter, when heat is wanted, and lesser exposure in the summer, when heat is to be avoided. Some Earthships, especially those built in colder climates, use insulated shading on the southern wall to reduce heat loss during the night. More....

The Greater World Community

The Greater World Community is a housing development in Taos, New Mexico that consists entirely of earthships. The Greater World became a legal subdivision in 1998, and is now phasing its development so that building can continue in certain sections of the development. The project was designed to create an ideal condition from which a sustainable community can grow and flourish. This whole community produces their own energy, harvests their own water, contains and treats their own sewage, manufactures bio-diesel, and grows a great deal of their own food. The buildings also heat and cool themselves all the while utilizing the discarded materials of our society. This community attempts to lead a non-destructive existence that removes stress from the lives of people and the planet. More....