An Earthship is a building with a soul. It is designed as a self-contained, low impact land-based ‘ship’ – constructed largely from what others throw away and designed to work in harmony with our environment using simple physics and common sense design.
It is defined by its originator, Mike Reynolds, as a building that conforms to the following six principles:
- Built with natural/recycled materials
- Thermal/Solar Heating and Cooling
- Solar & Wind-generated (renewable) electricity
- Water Harvesting
- Food Production
- Contained Sewage Treatment
Its also an answer to many of the problems that have been allowed to develop through the industrialisation and ‘modernisation’ of society into a mass consumer species.
Its a positive statement, a home that aspires to be more than a building – a sustainable and responsible way of life.
On the practical side
An Earthship is typically made up of an external wall of rammed-earth tyres, with a fully glazed, equatorially facing frontage; to maximise the passive solar gain from the suns rays. The sides of the Earthship are surrounded by banked earth, creating a large thermal capacitor with which to store the thermal energy. Throughout the day, when the air is warmer, than the earth thermal mass surrounding the earthship, thermal energy is absorbed into the tyre walls. When the air cools, especially at night, the thermal energy is released by the tyre walls, equalising the temperature and providing a consistent ambient temperature throughout the year. The typical layout is (but not limited to) is a series of modular U-shapes, providing an optimal depth to the building to ensure that the rear living areas are comfortable, whilst the front atrium ‘super-heats’ in the sun and yet not too far away to prevent the heat transfer into the rear tyre wall. The design allows low winter sun to penetrate further into the building, whilst the high summer sun is contained at the front. This is combined with natural ventilation openings to allow air to circulate, a further tool to regulate the internal room temperature.
Non-loadbearing walls may be constructed from numerous forms of recycled or natural materials. Bottles and aluminium cans are often used to provide a honey-combed structure to the mortar or ‘concrete’. The previously mentioned atrium formed by the full-frontal glazing, provides a prime habitat for food production. Typically planters are constructed along the inside of the atrium, providing food, texture and shade for the occupants.
The roof structure is made of timber trusses, covered with a suitable material for capturing potable water. This typically drains off the roof into large cisterns. It is from this capture method and these cisterns that the water starts the first of four journeys through the Earthship.
(1) The water flows through the Water Organising Module (WOM) where it is filtered and pumped into a traditional header tank.
(2) From here it is distributed as water for drinking, cooking and cleaning.
(3) The used water then becomes “grey water” that is course filtered and feed into the planters, providing water to the plants
(4) Grey water that remains after it has been though the planters is then pumped into the toilet cistern, where the resulting “black water” is flushed into a septic stank where it is broken down and allowed to leech into a reed bed, feeding the surrounding soil.
Hot water can be provided by solar hot water panels mounted on the roof of the Earthship or integrated solar PV with heat pump technology.
Electrical power is provided via micro generation on site, be it solar, wind, mini-hydro or any other creative, renewable means.
The resulting building does not rely on typical mains utilities and does not contribute to the impact attributable to these large scale distributed systems. As a result typical operating costs for an Earthship have been estimated at approximately US$100 per year. This in itself affords a better quality of life with reduced living costs.