An Earthship is a type of passive solar house that is made of both natural and recycled materials (such as earth-filled tires), designed and marketed by Earthship Biotecture of Taos, New Mexico. The term is a registered trademark of Michael Reynolds, founder of Earthship Biotecture.
Earthships are intended to be "off-the-grid ready" homes, with minimal reliance on both public utilities and fossil fuels. Earthships are constructed to use available natural resources, especially energy from the sun. Earthships are designed to use thermal mass construction and natural cross ventilation, assisted by thermal draught (Stack effect), to regulate indoor temperature.
The Earthship as it exists today began to take shape in the 1970s. Michael Reynolds wanted to create a home that would do three things: first, it would utilize sustainable architecture, and material indigenous to the local area or recycled materials wherever possible; second, the homes would rely on natural energy sources and be independent from the "grid"; finally, it would be feasible for a person with no specialized construction skills to build.
Eventually, Reynolds' vision took the form of the common U-shaped earth-filled tire homes seen today.
Construction and Design
The buildings are often horseshoe-shaped to maximize natural light and solar-gain during winter months, with windows on sun-facing walls admitting light and heat. 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 theoretically be used to create a building similar to an Earthship. The tire walls are strengthened by using concrete in the tires on the ends, called "concrete half blocks".
The earth-rammed tires of an Earthship are assembled by teams of two people. One member of the team shovels dirt, which usually comes from the building site, and places it into the tire one scoop at a time. The second member, 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 avoid warping the tire. Rammed earth tires can weigh up to 300 pounds so they are typically made in place. A finished earth-rammed tire is large enough to surpass conventional requirements for structural load distribution to the earth. Because the tire is full of soil, it does not burn when exposed to fire. In colder climates extra insulation is added on the outside of the tire walls.
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 located inside the top tires. Wooden shimming blocks placed on top of the wooden bond beam make up the wooden shoes. The wooden bond beam two layers of lumber bolted on to the concrete anchors. Re-bar is used to "nail" the wooden shoes to the wooden bond beam.
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 prevent heat loss.
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, snow, and condensation. 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 water organization module (WOM) that filters out bacteria and contaminants and makes it suitable for drinking. The WOM consists of filters and a DC-pump that are screwed into a panel. Water is then pushed into a conventional pressure tank to create common household water pressure.
Water collected in this fashion is used for every household activity except flushing toilets. The water used for flushing toilets is what is known as greywater and has been used at least once already. Typically it is filtered waste-water from sinks and showers.
Greywater, used water that is unsuitable for drinking, is used within the Earthship primarily for flushing toilets. Before the greywater can be reused, it is channeled through a grease and particle filter/digester and into a 30"-60" deep rubber-lined botanical cell, a miniature living machine, within the Earthship. In the botanical cell the water is oxygenated and filtered using bacteria and plants to reduce the nutrient load. 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 greywater board and used to flush conventional toilets.
Black water, water that has been used in a toilet, is sent to a solar-enhanced septic tank, referred to as "the incubator", that utilizes anaerobic digestion. The solar-enhanced septic tank is a regular septic tank which is heated by the sun and glazed with an equator-facing window. The incubator stores the sun's heat in its concrete mass, and is insulated, to help the anaerobic process. Water from the incubator is channeled out to an exterior leach field and then to landscaping "planter cells", concrete cells containing plants. The cells are similar to the botanical cell used in greywater treatment and are usually placed just before and under the windows of the earthship.
In cases where it is not possible to use flush-toilets operating on water, dry solar toilets are recommended.
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 windturbines located on or near the Earthship generate DC energy that is then stored in several types of deep-cycle batteries. The space in which the batteries are kept is usually a special, purpose-built room placed on the roof. Additional energy, if required, can be obtained from gasoline-powered generators or by integrating with the city grid.
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. It includes the necessary equipment such as circuit breakers and converters. The energy run through the Power Organizing Module can be used to run any household appliance including washing machines, computers, kitchen appliances, print machines, and vacuums. Ideally, none of the electrical energy in an Earthship is used for heating or cooling.
Earthships rely on a balance between the solar heat gain and the ability of the tire walls and subsoil to transport and store heat. They are designed to use the properties of thermal mass and with the intent that the exterior earth-rammed tire walls provide 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 the exterior tire walls, some Earthships are sunk into the earth to take advantage of earth-sheltering to reduce temperature fluctuations.
Some earthships appear to have problems with heat loss. In these cases heat appears to be lost into the ground during the heating season. This may be due to belief that ground-coupled structures, buildings in thermal contact with the ground, do not require insulation. It also may be due to climatic differences between New Mexico where earthships were first built and cloudier, cooler, and wetter climates. Thermal performance problems seen in some earthship designs may also have occurred due to thermal mass being erroneously equated to R-value. The imperial R-value of soil is about 1 per foot. Malcolm Wells, an architect and authority on earth-sheltered design, recommends an imperial R-value 10 insulation between deep soils and heated spaces. Wells's insulation recommendations increase as the depth of the soil decreases.
In addition to thermal mass, Earthships also use passive solar heating and cooling. Large front windows with integrated shades, trombe walls and other technologies such as skylights or Steve Baer's "Track Rack" solar trackers are used for heat regulation. Earthships are positioned so that its principal wall, which is nonstructural and made mostly of glass sheets, faces directly towards the equator. This positioning allows for optimum solar exposure. To allow the sun to heat the mass of the Earthship, the solar-oriented 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 solar-orientated wall to reduce heat loss during the night.
The earthships usually use their own natural ventilation system. It consists of cooler air coming in from a front "hopper" window and flowing out through one of the skylights. As the hot air rises, the system creates a steady airflow - of cooler air coming in, and warmer air blowing out.
In 2000, Michael Reynolds and his team came to build the first residential earthship in Boingt (Belgium). While water, power module, solar panels and the team were on their way to Europe, the mayor of Boingt put his veto on the building permit. Josephine Overeem, the woman who wanted to build the earthship, and Michael Reynolds decided to do a demonstration model in her back yard at her residence in Strombeek (Belgium). CLEVEL invited Reynolds from Belgium to Brighton in the UK, and orchestrated plans for the earthship in Brighton, started in 2003. This was the beginning of a series of trips made by Reynolds and the construction of earthships in the UK, France and the Netherlands.
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 with the Low Carbon Trust.
In 2007, CLEVEL and Earthship Biotecture obtained full planning permission to build on a development site overlooking the Brighton Marina in the UK. The application followed a six-month feasibility study, orchestrated by Daren Howarth, Kevan Trott and Michael Reynolds and funded by the UK Environment Agency and the Energy Savings Trust. The successful application was for sixteen one, two, and three-bedroom earthship homes on this site, expected to have a sale price of 250 - 400,000 pounds. The homes are all designed according to basic earthship principles developed in the United States and adapted to the UK. 15,000 tires will be recycled to construct these homes (the UK 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 would have been the first development of its kind in Europe.
The first official Earthship home in mainland Europe with official planning permission approval was 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. It is currently used as a holiday home for eco-tourists.
Further adaptation to the European context was undertaken by Daren Howarth and Adrianne Nortje in Brittany, France. They obtained full planning permission in 2007 and finished the Brittany Groundhouse as their own home during 2009. The build experience and learning is documented in the UK Grand Designs series and in their book.
Meanwhile, earthships have been built or are being built in Portugal, Spain, France, Belgium, The Netherlands, United Kingdom, Sweden, Denmark, Germany, Estonia and Czech Republic. A good overview of the earthships built in Europe can be found on the web page of European Earthship Builder United, together with information on earthships being built. A good chronological overview on the earthships built in Europe by Michael Reynolds can be found in the article 'Europe'.
The first official earthship district (23 earthships) in Europe is currently being developed in Olst (the Netherlands). Building will start in spring 2012. In Belgium, 1 earthship hybrid is also being built, intended as demonstration buildings. Since it is illegal to use tires in Belgium (for risk of leaking toxic metals like lead and zinc), the project uses earthbags to build their earthship instead.
The Earthships built in Europe by Michael Reynolds aren't always performing as promised and some show problems with moisture and mould. Some research into performance was done by the University of Brighton on the Brighton Earthship. which was then used to create the most detailed thermal monitoring ever carried out on an earthship (reported with a series of design recommendations to make earthships more effective in different climatic conditions in the book Earthships: building a zero carbon future for homes )
The first earthship in South Africa was built by Angel and Yvonne Kamp from 1996 to 1998. They rammed a total of 1,500 tires for the walls. The earthship, near Hermanus, is located in a 60 hectare private nature reserve which is part of a 500000 hectare area enclosed in a game fence and borders the Walker Bay Nature Reserve.
The second earthship in South Africa is a recycling centre in Khayelitsha run as a swop shop concept. The centre was finished in December 2010. Another low cost house built with tyres is in development in Bloemfontein.
A project nearing completion in South Africa is a combined living quarters for 4 to 5 people, a bed and breakfast, and an information/training centre in Orania. This earthship is based on the global earthship model and is built with a foundation of tyres, has roof bearing walls built with earthbags, and interior walls built with cob, cans and plastic bottles. This earthship adheres to all six principles of an earthship. This is the largest earthbag earthship in the world.
In 2011, construction began on the Goderich Waldorf School of Sierra Leone. The school was the first educational institution to use earthship architecture. Although Mike Reynolds and a team of interns helped complete the first two classrooms, the majority of the building was built by community members who had been trained in Reynolds' building techniques.
The first Earthship in South America was built in January 2015 in the town of Ushuaia, Patagonia (Argentina). Today this building functions as a visitor center and example of self-sustainable living.
An earthship is currently (2015) under construction by the Aitkinson family in southern Belize. It featured on the June 2015 UK Channel 4 TV programme Kevin McCloud's Escape to the Wild, season 1, episode 3.
Guatemala also hosts two earthships.
In popular culture
The film Garbage Warrior is about Earthships and Reynolds' struggle with the law.
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- Contractor’s Report to the Board: Designing Building Products Made With Recycled Tires. Published by the California Integrated Waste Management Board in June 2004. Produced under contract by: Chris Hammer, The Elements Division of BNIM Architects Terry A. Gray, T. A. G. Resource Recovery. Accessed at: http://www.calrecycle.ca.gov/Publications/Documents/GreenBuilding%5C43304008.pdf on 5 February 2015.
- Hewitt, M. and Telfer, K. (2007). Earthships: building a zero carbon future for homes. ISBN 978-1-86081-972-8
- Klippel, James H. http://www.garrellassociates.com/EcoDesign.html, green page
- Howarth, D. & Nortje, A. (2010). "Groundhouse Build & Cook". ISBN 978-0-9566947-0-6
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