An Earthship is a type of passive solar house that is made of both natural and upcycled materials such as earth-packed tires, pioneered by architect Michael Reynolds.
An Earthship addresses six principles or human needs:
- Thermal/solar heating and cooling
- solar and wind electricity
- self-contained sewage treatment
- building with natural and recycled materials (old tires, glass bottles, and cans)
- water harvesting and long term storage (rain capturing system)
- some internal food production capability (built- in greenhouse)
Earthship structures are intended to be "off-the-grid-ready" homes, with minimal reliance on public utilities and fossil fuels. They are constructed to use available natural resources, especially energy from the sun and rain water.
They are designed with thermal mass construction and natural cross-ventilation to regulate indoor temperature.
The designs are intentionally uncomplicated and mainly single-story, so that people with little building knowledge can construct them.
The book, Earthship I, describes how to find the best angle depending on the building's geospatial location. The thick and dense walls provide thermal mass that naturally regulates the interior temperature during both cold and hot outside temperatures. The outer walls in the majority of Earthships are made of earth-rammed tires, but any dense material with a potential to store heat, such as concrete, adobe, earth bags, or stone, could in principle be used to create a building similar to an Earthship. The tire walls are staggered like traditional brick work, and often have "concrete half blocks" every other course, to equal the length of the staggered tire below. In an effort to cut down the use of concrete even further, they also use "squishies" - tires rammed in between a tight space to even out the course or to compensate for varying tire size.
Most earthship structures are earth-sheltered buildings with a large series of windows and use tires
The earth-rammed tires of an Earthship are assembled by teams of two people. One person shovels dirt and places it into the tire one scoop at a time. The other person, who stands on the tire, uses a sledgehammer to pack the dirt in while moving in a circle around the tire to keep the dirt even and to avoid warping the tire.
Rammed earth tires can weigh up to 300 pounds, so they are typically filled in place. Because the tire is full of soil, it does not burn when exposed to fire.[2] In colder climates, extra insulation is added on the outside of the tire walls.
Tires rammed with earth and stacked
On top of the tire walls are either "can and concrete bond beams" made of recycled cans joined by concrete, or wooden bond beams with wooden shoes. These are attached to the tire walls using concrete anchors, poured blocks of concrete inside the top tires. Wooden shimming blocks placed on top of the wooden bond beam make up the wooden shoes. The wooden bond beam consists of two layers of lumber bolted on to the concrete anchors. Re-bar is used to "nail" the wooden shoes to the wooden bond beam.
Internal, non-load-bearing walls are often made of a honeycomb of recycled cans joined by concrete; these are nicknamed tin can walls. These walls are usually thickly plastered with adobe, and resemble traditional adobe walls when finished.
The roof is made using trusses, or wooden support beams called vigas, that rest on the wooden shoes or the tin can walls placed on the bond beams. The roof as well as the north, east and west facing walls are heavily insulated to reduce heat loss.(
