The term Earthship describes a particular type of house that, in the terms of Michael Reynolds, “interfaces” with the earth rather than combats it as is the case with most traditionally built structures. Although there is a specific organization founded by Reynolds, known as Earthship Biotecture, that constructs these houses the Earthship is meant to be a house that can be built by a layperson without having to receive the permission of the organization. Earthships are presented as highly sustainable structures. Therefore I decided to focus my research on the merit of this claim in relation to specific areas. The areas I chose to focus on were the employment of natural and passive systems within the design, the reuse of materials, and the social accessibility of the Earthship.
Though many Earthships have been built, there is a standard method and module of construction amongst them. They can be easily distilled into their most fundamental components and described by the concept of “interfacing” with the Earth. Earthships exemplify many of the concepts we have discussed in class, namely, that of designing to exist within and as a part of existing natural systems rather resisting these systems by employing manmade infrastructure. Reynolds clearly defines the systems we use in traditional in his book, Earthship, as well as the ways in which Earthship design addresses these systems: Energy production and distribution (primarily electricity and heating and cooling), water, sewage, gas, food, materials, and monetary systems. Reynolds argues that each of these systems which are currently met by large-scale manmade infrastructure can be met instead by designing to meet natural conditions. For the purposes of this assignment, I categorized these systems into the previously mentioned areas of study, although of course, there some overlap. Natural systems encompass heating and cooling, food, and water. Reuse of materials also includes water as well as materials and sewage, and monetary systems falls under social accessibility. Electrical energy production will be discussed separately. An important concept in an Earthship that is made evident by the overlap of these systems is the idea of multi-functional spaces and systems rather than isolated elements.
Evaluating the sustainability of the Earthship equates to understanding the processes that allow for the house to operate off the grid. We have studied many of these systems in class. The primary system of the Earthship is that of capturing and storing energy from the Earth and the Sun. Orientation and placement of individual Earthship modules determines its ability to do this. A key requirement of an Earthship is that it is built into the Earth rather than constructed above it. The purpose of this is to provide the house with as much thermal insulation as possible. The greater the thermal mass of the Earthship, the greater its ability to retain heat and disperse it over a longer period of time. This ensures that the interior of the house maintains a relatively constant temperature regardless of fluctuating temperatures outside.
This placement within the ground is coupled with the construction strategy of the module. Each module has a thermal U-shaped structure made from used tires packed with earth paired with a south facing wall of windows that creates the greenhouse. The glass wall of the greenhouse is sloped according to the geographic location of the particular Earthship. For New Mexico, the state in which the original Earthships were designed, the slope of the greenhouse is 30 degrees in order to capture the direct light of the sun at noon on the winter solstice. This direct sunlight will allow the thermal mass of the Earthship to gain and retain the maximum amount of heat on the day of the year with the least amount of sun. It will also reflect much of the direct sunlight on the summer solstice in order to keep the Earthship module cool during the summer. Earthships located farther north will want to have less of a slope on the greenhouse wall in order to allow the direct sunlight of a lower sun into the space. Earthships in a hot and humid climate will need the glass wall to face north to avoid extreme solar gain.
FOOD AND AIR
Another important factor in the climate of the interior is the circulation of air through the space. Vents in the lower part of the greenhouse wall (or in some cases air ducts located underground) will draw air into the space. A skylight is always located at the top in order to draw the hot air out of the space and continue to draw in cool air, keeping the space cool on hot days. Air also plays an important factor in terms of the food system. A concept that is central to the idea of the Earthship as independent of existing infrastructure is that of being able to produce its own food. Obviously this concept is dependent on having a functioning greenhouse that can produce a sufficient amount of food as well as create an environment in which the inhabitant is in direct relationship with the photosynthetic process. This also exemplifies the idea of multi-functional space. The greenhouse is both the source of food and the means by which the house gains heat and ventilation.
Water is another essential system that typically relies on large scale infrastructure. The Earthship employs a rainwater collection technique that catches runoff from the roof in a rain barrel. The water is then filtered through a sand filter into a storage tank from which it can be pumped into the house. Once the water is used in the house, the greywater can also be used to water the garden. Rather than employing the typical wastewater treatment systems, some Earthships have adopted a system similar to the living machine. A living machine is based on the natural process of cleaning water. Certain aqueous plants and ground conditions are suitable for the aggregation of the bacteria that break down waste. The living machine recreates these conditions in order to handle wastewater in a decentralized manner. In the case of the Earthship, the water that comes out of this method of treatment can be reused both in the house to flush toilets and in the garden to water plants.
The treatment and reuse of water leads to the concept of recycling materials. When first brainstorming ideas for materials to be used in the Earthship, Reynolds first came up with the criteria that the material had to provide the appropriate amount of thermal mass, provide the structural strength needed to support a structure that is partially buried in the ground, and that was also readily available to the common person. A used car tire packed with earth was his solution. Not only does this meet the criteria, but it also provides a use for the nearly infinite number of used car tires that have no function and cannot be broken down and is readily available in most areas. The tires act as the core of the thermal walls and would then be coated by some sort of local material, perhaps sod or concrete. The materials that are used to build the roof and greenhouse structure are meant to be local and readily available.
SOCIAL ACCESSIBILITY AND CRITICISM
This addresses the final area of study of the social accessibility of Earthships. Because Earthships are made from relatively inexpensive materials that are readily available, they are can be an attainable goal for most people. The method of construction of an Earthship is also meant to circumvent many processes of traditional construction. They are meant to be constructed by the people who will inhabit them.
One criticism of the Earthship involves this issue. The main source of energy for the house is meant to be photovoltaic panels installed on the roof. Although this allows the Earthship to be off the grid, it negates the concept of affordability. We have also discussed in class the fact that photovoltaic panels require energy to produce than they will make up for in providing energy to a home. What this really brings up is the issue of adaptability of the inhabitants. We have discussed how the successful systems are those that are resilient and adaptable rather than efficient and unyielding. David Sheen responds to these criticisms by saying that an unwillingness to live with limited supplies of water and electricity is incompatible with the self-sufficiency of these buildings. This goes along with the willingness to take on the intense labor that is required to build one’s own Earthship. Clearly the lifestyle, the labor, and the aesthetic that are all involved with inhabiting an Earthship is an issue in terms of implementing this type of self-sufficient housing. Perhaps the photovoltaic issue means that the inhabitants should also adapt to live without an unlimited supply of electricity. The sustainability of the Earthship does not equate to meeting the current expectations of housing. To adapt to the lifestyle required by a housing model like this one will require a fundamental shift in the way we view housing from viewing it as a series of unrelated events to viewing it as a system of interconnections.
- Reynolds, Michael, E. Earthship. Taos, NM: Solar Survival, 1990.
- Ip, K. ; Miller, A. “Thermal Behaviour of an Earth-Sheltered Autonomous Building.” Renewable Energy Vol. 34, Issue 9, (2009): pp. 2037-2043
- Sheen, David. (5 November, 2011) “Critical Analysis.” Retrieved from http://www.davidsheen.com/earthship/critique.htm
- Earthship Biotecture. (24 October, 2011) “Earthship Systems.” Retrieved from http://earthship.com/systems
- Living Machine. (17 June, 2011). “How It Works.” Retrieved from http://www.livingmachines.com/about/how_it_works/