Earthships are constructed to take advantage of available natural resources in the immediate vicinity, particularly in the form of solar energy. The buildings are often horseshoe-shaped and oriented to maximize natural lighting and heat-gain from the sun. Interior climate is regulated by thermal mass walls, constructed from earth-rammed tires, in keeping with the ethos of using primarily reclaimed materials.
In the same spirit, the interior walls are generally constructed of a honeycomb of tin cans, joined with concrete and plastered over. These walls are non-load bearing, while other facets of the house's construction are accomplished with more traditional wooden building materials. As in all passive houses, the Earthship's walls and ceiling are heavily insulated in order to minimize the loss of heat and maximize efficiency. Often, Earthships are constructed in such a manner that the ceiling and walls are covered, or Earth-sheltered, greatly increasing the potential thermal mass.
Another hallmark of Earthships is their self-reliance when it comes to water and electric needs. While most traditionally built homes are dependent upon centralized utilities, especially in urban areas, Earthships use alternative means to establish a true off-the-grid existence. Electricity is usually derived from solar cells or wind turbines, and stored in deep-cell batteries. A power organizing module is used to invert the stored electricity to AC current, allowing household devices to be operated as if the Earthship were directly connected to a municipal power grid.
Water reclamation is a bit more complicated in an Earthship. Collected from rain, snow, and condensation, water is filtered and stored for use in a cistern, which gravity-feeds into another filtering mechanism designed to remove bacteria and other contaminants. A pressure tank allows for conventional usage in showers and sinks.
Water that has already been used once in the household, called greywater, is stored and utilized a second time, exclusively for toilets. While early Earthships avoided the use of flushing toilets in favor of composting mechanisms, modern versions utilize greywater that has been processed through a botanical cell, a miniaturized living machine in which plants filter contaminants from the water. After passing through the toilet system, the "blackwater" is not reused in the Earthship, instead being routed to a solar-enhanced septic tank, complete with a system of biological cells, which allow the filtered water to automatically feed non-edible landscaping plants.
Ventilation in an Earthship is usually established through convection, with vents or skylights in the ceiling allowing warmer air to rise and pass out of the structure, while cooler air is drawn in through one of the windows. This naturally dynamic process allows for a consistent airflow.
Earthships have experienced a major uptick in popularity since the 2007 release of Garbage Warrior, a documentary about Mike Reynolds, the inventor of the Earthship building concept. The film chronicles the legal challenges he faces in constructing structures to which traditional building codes hardly apply. Any readers who are interested in learning more about Earthships are encouraged to check it out.
If you're a Saratoga Springs local or live in upstate New York, don't hesitate to contact Geodesic Earthworks, LLC for even more information on Earthships.