The Earthship is an architectural concept that arose in the late 1970s. The architecture Michael Reynolds set out to design and create a home that would do three things: first, it would encapsulate sustainable architecture by relying on local materials or recycled materials; second, the homes would depend on natural energy sources in order to be independent of the ‘grid’; and third, they would be designed in such a way that a person with no specialised construction skills could build their home.
The impressive features of an Earthship
Earthship Biotecture is a leading eco-construction and self-sufficient living company. It builds homes that are based on Reynolds’ vision. Its passive solar houses, made from natural and upcycled materials – such as earth-packed tires – address six human needs:
The structural walls of the building are formed with used automobile tires packed tightly with earth. These thermal mass “bricks,” which weigh about 300 pounds each, are pounded into place and staggered like bricks to form the load-bearing walls for the roof. The tires are also wide enough to eliminate the need for a concrete foundation.
The densely packed walls, considered to be self-supporting monolithic walls, also store temperature (heat or cold) because their solidity imbues them with the quality of thermal mass. The basic idea is to surround each living space with mass on three sides and line the south side of the building with windows. Sun enters through the glass and heats up the mass of the floors and walls.
In the evening, when the air temperature drops below the stored wall temperature, heat is naturally released into the space. In the summer, with the sun high in the sky, the building stays cool with the constant temperature of the earth. We enhance the cooling with natural ventilation through buried cooling tubes and operable vent boxes.
Every building has its own renewable “power plant” with photovoltaic panels, batteries, charge controller, and inverter. The key step in making these systems affordable for residential use is to “design down” the electrical requirements of the home before the solar system is sized.
Super efficient lighting, pumps, and refrigeration help lower the load, as does the lack of any need for electric heat or air conditioning. Add in daylight from the windows and skylights and a keen awareness of trickle drains and phantom loads, and an Earthship’s electrical needs are about 25 percent of that of a conventional home. Most residents can meet their demand with one kilowatt or less of energy from solar panels. Some also opt to add a small windmill to the system for gray, stormy climates.
The used gray water flows to interior botanical cells, where plants use up and treat the water until it’s clean enough to be collected in a well at the end of the planter and pumped, on demand, to the toilet tank for flushing. (Forty percent of water used in a conventional home is for toilet flushing.) The toilet water then goes to a conventional septic tank, which overflows into an exterior rubber-lined botanical cell filled with exterior landscaping plants.
Every drop of water that lands on an Earthship roof is used four times, so homes can subsist and even thrive without taking water from the ground or municipal sources.
Earthships incorporate many natural and reclaimed materials in their construction. Tires are the perfect form for a rammed-earth brick. There’s no shortage of used tires—at least 2.5 billion are currently stockpiled in the United States, with 2.5 million more discarded every year. Tires can be seen as a globally available “natural resource.”
Other materials such as cans and bottles are optional, although bottle brick walls are a familiar stand-out feature of many Earthships. All interior walls are packed out between the tires and plastered with adobe mud. Mud can also be used for floors, and reclaimed wood and metal are often used.
Earthships collect all of their water from rain and snowmelt on the roof, storing this water in cisterns. (Each inch of rain collected from a square foot of roof equals 2/3 of a gallon of water. Multiply that by the total square footage of the roof and number of inches of rain per year, and you get your total possible collection.)
Water from the cistern feeds a pump and filter system that cleans the water and sends it to a solar hot water heater and also to a pressure tank. From there, water is used for bathing, washing dishes, and laundry.
Interior, in-home, organic food production is the most recent design principle added to the Earthship concept. Earthship Biotecture employs a plant specialist who has experimented with the best plants for the interior gray-water botanical cells. She has also designed mini-hydroponic planters in suspended buckets that have added vertical growing space in the greenhouses and have tremendous yields of herbs, peppers, tomatoes, kale, beets, cucumbers, and more.
The Earthship Visitor Center features all of these food-producing plants, and staff members regularly enjoy fresh produce straight off the vine. Aqua-botanical systems in the newest Earthship enhance food production capabilities with fish and nutrients from their waste.
The company’s homes are intended to be ‘off-the-grid ready’, minimising their reliance on public utilities and fossil fuels.
Is sustainable housing really that expensive?
Many people believe that the biggest downside of sustainable housing is that it is costly. The problem, though, is that studies on housing standards usually rely on a cost-benefit analysis to assess the value of traditional housing versus sustainable housing, which ends up leading to the conclusion that the latter is unaffordable.
However, research indicates that these analyses exclude some key financial benefits of sustainable housing that make this kind of living, overall, quite affordable.
Findings show that Australian residents who live in sustainable housing use 45% less electricity than the control households (and 73% less than the industry standard) and 22% less water (and 30% less than the industry standard). This, of course, translates into cheaper energy bills. Sustainable housing also entails lower mobility costs.
We also can’t ignore the added benefits of sustainable housing, such as the fact that they have a 40% less CO2 environmental impact from power use (and 63% less than the industry standard). Moreover, we shouldn’t ignore the massive, hidden costs of climate change. Other overlooked effects include householders’ health and quality of life that arises from factors such as improved thermal comfort.
Residents living in sustainable homes also report that, by saving money on bills, they can spend more money on gifts for their children, avoid personal debt, and take more holidays. This leads to reduced stress and better mental health.
While it may be tempting to think that Earthships must be extremely cheap since they are made from old tires and dirt, this view is mistaken. Most reports underscore that they cost just as much to build as a conventional house (although, as the previous points highlight, the money-saving, environmental, and comfort benefits of an Earthship could make it far more valuable than a standard house).
Earthships are far from perfect, but the principles on which they are based certainly provide inspiration for how to live sustainably and self-sufficiently.
About the author: Sam Woolfe @samwoolfe
Sam is a freelance writer who is particularly interested in space exploration, sustainability, tech, and agriculture.