A regular earthship

Earthships refers to a passive solar home made of natural and recycled materials. Designed and marketed by Earthship Biotecture of Taos, NM, the homes are primarily constructed to work autonomous and are generally made of earth-filled tires, utilising thermal mass construction to naturally regulate indoor temperature. They also usually have their own special natural ventilation system. Earthships are a type of off-grid home, which minimizes their reliance on public utilities and fossil fuels.

Earthships are built to utilize the available local resources, especially energy from the sun. For example, windows on the sunny side admit light and heat, and the buildings are often horseshoe-shaped to maximize southern (or nothern in the southern hemisphere) sunlight and warmth in the colder months. Likewise, the thick, dense outer walls provide effective insulation against summer heat.

Internal, non-load-bearing walls are often made of a "honey comb" of recycled cans joined by concrete and are referred to as tin can walls. These walls are usually thickly plastered with adobe or stucco.

The roof of an Earthship is heavily insulated - often with earth or adobe - for added energy efficiency.

History

The Earthship, as it exists today, began to take shape in the 1970s. Mike 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, using material indigenous to the entire planet as well as recycled materials wherever possible. Second, the homes would rely on natural energy sources and be independent from the “grid”, therefore being less susceptible to natural disasters and free from the electrical and water lines that Reynolds considered unsightly and wasteful. Finally, it would be economically feasible for the average person with no specialized construction skills to be able to create.

Eventually, Reynolds' vision took the form of the common U-shaped earth-filled tire homes seen today. As a concept, the Earthship was not limited to tires - any dense material with a potential for thermal mass, such as concrete, adobe, or stone could theoretically be used to create an Earthship. However, the earth-rammed tire version of the Earthship is now the most common design, and is usually the only structure referred to as “Earthship”.

Unlike other materials, rammed-earth 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[verification needed]. In addition to the availability of scrap tires, the method by which they are converted into usable "bricks", the ramming of the earth, is simple and affordable.

The earth rammed 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.

Additional benefits of the rammed earth tire are its great load-bearing capacity and its resistance to fire.

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. In 1996 after a fire swept through many conventional homes in New Mexico, an Earthship discovered in the aftermath was relatively unharmed[verification needed]. Only the south-facing wall and the roof had burned away, compared to the total destruction of the conventional homes. After testing the walls of an Earthship in Ridgway, Colorado, engineer Tom Griepentrog said, “It is my opinion that the construction method is equivalent to or better than the general quality, strength, effectiveness, fire resistance, durability and safety that is required by the uniform building code.”[verification needed]

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. In the year 2000, Mike Reynolds, in partnership with Daren Howarth, launched Earthship Biotecture Europe, an organization that aims to explore and evolve the concept of the Earthship within a European context. Two more directors were appointed to Earthship Biotecture Europe in July 2006 - Kevan Trott and Kirsten Jacobsen [1]

Types

Since its start-up, Earthship Biotecture has been building and inventing new types of earthships, so that at present, 3 types can be distingueshed (all of which can be still bought today).

Packaged Earthship

The most versatile and economical Earthship in terms of construction and building is the packaged earthship. This earthship comes in (partially) prefabricated construction packages and with pre-designed drawings. This "Off-the-rack" aspect makes it a fairly easy to construct building. Sizes begin at a 607 square foot ("Nest" studio) and go up to a 3 bed, 2 bath Earthship and larger.

Modular Earthship

Modular Earthships provide as the name implies, the ability for the buyer to compose his earthship entirely to his liking. A greater variety of spaces than packaged Earthships and more sculptural rooms are available herefore. Because all the rooms are equipped with thermal mass insulation, the earthship will still provide in its thermal stability it is famous for.

Hybrid/Nautilus Earthship

The Nautilus Earthship is a unique spiral design earthship based on a sea shell. The idea around this is that Earthships need to interact with this planet's natural phenomena; thus the sun, the wind, the thermal mass of the earth, the rain, and even the spiral pattern in all life. [1]

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 of Water, Electricity and Climate. While these systems are not exclusive to Earthships, a properly designed Earthship must have these systems.

Water

Earthship water system

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. The cisterns are positioned so they gravity feed a WOM (water organization module), that filters out bacteria and makes it suitable for drinking. Water is then pushed into a conventional pressure tank to create common household water pressure. Water collected in this fashion is used for any household activities except flushing toilets (Reynolds 2000).

Treating and reusing greywater
Greywater, water that has been used and is unsuitable for drinking, is used within the Earthship for a multitude of purposes once it is reclaimed. First, 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, a miniature living machine, within the Earthship. Oxygenation, filtration, transpiration and bacteria encounter all take place within the cell and help to cleanse the water (Reynolds 2000). Within the botanical cell filtration is achieved by passing the water through a mixture of gravel and plant roots. Because of 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.

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(see earthship.net) and used to flush conventional toilets.

Often, any greywater that is made at earthships, is not polluted enough to justify treatment (its "pollution" being usually just soap, which is often not environmentally damaging). At earthships, the use of plants placed at outlets of fixtures is then practiced to regain the nutrients lost (from the soaps, ...) and water from the greywater. Usually, a single plant is placed directly in front of the pipe, but mini drain fields are also sometimes used. The pipe is made large enough (5,08cm) so that the formation of underground gas (from the greywater) is avoided. This is done with kitchen, bathroom sinks and even showers, washing and dishwashing machines. The plants are usually placed indoors with the sinks and outdoors with the washing/dishwashing machines and shower (to avoid indoor "floods"). Also, with the latter, larger drain fields are used instead of a mere placing before a outlet. [2][3]

Treating and reusing black water
Black water, water that has been used in a toilet, was usually not created within many earthships as the use of conventional toilets was discouraged. [4] Instead, composting toilets were advocated, which use no water at all. However, with the new designs created by Michael Reynolds, flush toilets have now found a place in the earthship and the general water system has been redesigned according to the new "6-step process".[5][6] Now, when the newly included flush-toilets are used, blackwater 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

Collection 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.

Conversion and use
In an Earthship, a Power Organizing Module is used to take stored energy from batteries and invert it for AC use. The Power Organizing Module is a prefabricated system provided by Earthship Biotecture that is simply attached to a wall on the interior of the Earthship and wired in a conventional manner. The energy run through the Power Organizing Module can be used to run any house hold appliance including: Washing machines, computers, kitchen appliances, print machines, vacuums, etc. None of the electrical energy in an Earthship is used for heating or cooling. [2]

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. Examples are trombe walls and other technologies as skylights.

Thermal Mass
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.

Passive Solar Heating and Cooling

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 (Reynolds 2000).

Natural ventilation

The natural ventilation system used in earthships

The earthships usually use their own natural ventilation system. It consists of cold(er) air coming in from a front window, especially made for this purpose and flowing out through (one of) the skylights that are placed on the eartship. As hot air rises, the system maintains itself and keeps sucking in (and out), air.

Heating Problems

Earthships rely on a balance between the solar heat gain and the ability of the tire walls and subsoil to transport and store heat. The design intends to require little if any auxiliary heat. Some earthships have suffered from over-heating and some from over-cooling, because of a failure to adjust for local conditions.

Some earthships appear to have serious problems with heat loss. In these cases heat appears to be leaking into the ground constantly during the heating season and being lost. This situation may have arisen from the mistaken belief that ground-coupled structures (building in thermal contact with the ground) do not require insulation. The situation may also be due to large climatic differences between the sunny, arid and warm Southwest (of the USA) where earthships were first built and the cloudier, cooler and wetter climates where some are now being built. Malcolm Wells, an architect and authority on earth sheltered design, recommends R-value 10 insulation between deep soils and heated spaces. Wells's insulation recommendations increase as the depth of the soil decreases.

In very limited and specific situations, uncommon during the heating season, thermal mass can marginally increase the apparent R-value of a building assembly such as a wall. Generally speaking thermal mass and R-value are distinct thermodynamic properties and should not be equated. Thermal performance problems apparently seen in some earthship designs may have occurred because of thermal mass being erroneously equated to R-value.

According to the Kansas State University Extension Service the R-value of soil is about 1 per foot.

Potential advantages

  • Having an earth-bermed home with windows facing the sun is a good idea in any climate where heating is required.
  • Collecting rainwater that falls on the roof reduces the runoff impact of the building and may reduce water and even sewer service fees.
  • Having a combination of photovoltaic cells and wind generation is a prudent way to provide electricity in many situations.
  • Using curved modules as horizontal arches to resist earth loads is a sound structural design.
  • On-site processing of runoff water, grey water and black water using plant beds reduces the environmental impact of the building.
  • Rubber tires make a wind and puncture resistant wall. They may be safe from outgassing when plastered semi airtight.
  • Rubber tires are usually free and it may be possible to be paid to take them.

Potential disadvantages

  • The sloped glazing may be hard to keep watertight and in warm climates allows excessive solar gain in summer. In colder climates, the glazing itself, which has far poorer insulating properties than any other component, will obviously be the major conduit of heat loss in winter. New designs call for vertical windows with an overhang.
  • Uninsulated ground-coupled thermal mass presents a large potential for heat loss, especially in climates with a heating season. This varies to a degree with soil type and moisture content.
  • Rubber tire walls tend to lack structural stiffness and may require perpendicular stiffening ribs.
  • The novel design may diminish resale value or make buyers more difficult to find.
  • The intimate ground contact inherent in this approach may increase hazards due to soil gases including Radon, and those due to water intrusion.
  • Packing or ramming dirt into the inside of tires is a very labor intensive process.
  • Many Earthship builders are drawn to this system by its apparently low environmental impact. However, this is only valid if the design is highly thermally efficient. Earthship designs may require substantial thermal analysis and redesign to be adapted to non-Southwest USA climates.
  • Free or cheap tires would not be available in a society which managed its resources sustainably --- they would have an economic value. The most sustainable material is presumably stone.
  • Earthships built with concrete, sand bags or adobe and with better solar and heat control perform better and are less environmentally damaging. Due to the environmentally unfriendly nature of tyres, it is even illegal to use tyres in certain countries (ie Belgium)[7]. Earthship Belgium hence uses sandbags to built their earthships instead.

Earthships around the world

Most of the eartships are still located in New Mexico (especially around Taos). However, the first official Earthship home in Europe has now been built in a small French village called Ger. The home, which is owned by Kevan and Gillian Trott, was built in April 2007 by Kevan, Mike Reynolds and an Earthship Crew from Taos. The design was modified for a European climate and is seen as the first of many for the European arena. www.earthship-france.com or www.earthship.net

Earthship biotecture has now also finalized plans for a planning application to build on a valuable development site overlooking the Brighton Marina in the U.K. The application follows the successful six-month feasibility study funded by the U.K. Environment Agency and the Energy Savings Trust. The application calls for sixteen one, two, and three-bedroom earthship homes on this site. The homes are all designed according to basic earthship principles developed in the United States. 15,000 tires will be recycled to construct these homes, which is definitely a small but progressive step for the earth's environmental health considering the fact that the U.K. burns approximately 40 million tires each year. The plans include the enhancement of habitats on the site for lizards that already live there, which is the reasoning behind entitling the project, The Lizard. This will be the first development of its kind in Europe, and successful development in Brighton may help to pave the way for similar projects around the U.K. and other places. [3]

In 2004, the very first Earthship in the UK was opened at Kinghorn Loch in Fife, Scotland. It was built by volunteers of the SCI charity. In 2005, the first earthship in England was established in Stanmer Park, Brighton.

The worldwide earthship community

At present, Michael Reynolds is building a worldwide network of communities, focused on spreading the technique of building earthships and doubling as a presentation. The communities consist of housing developments in Taos, New Mexico, uniquely constructed of earthships. Communities include REACH and STAR. [8] Also, another organisation has been set up, called The Greater World and is also focused on helping people on building earthships. This organisation however is more focused on helping out with building codes (which are often problematic for earthships, given that they require other plumbing, ...). [9] 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. [4]

See also

Applications:

References

Reynolds, Mike. (2000). Comfort In Any Climate, Taos: Solar Survival P. ISBN 0962676748

Interwiki links


External links

   * Step-by-step construction techniques, Earthship tours
   * Earthship Biotecture
   * Sustainable Communities Initiatives - UK Earthship visitor centre
   * Info on earthships in the UK
   * Touch the Earth Earthship
   * Very detailed construction information/photos and good links
   * Passive solar, high thermal mass construction
   * Homepage von Earthship Austria in Deutsch
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