Earth-sheltered homes, also known as earth-berm homes or underground homes, can be constructed using a variety of materials. While some homes are constructed using an assortment of recycled materials to lower building costs and practice environmental consciousness, others are built using more traditional materials such as lumber, sheetrock, fiberglass insulation, adobe, and concrete. Many earth-sheltered houses are constructed using a combination of both traditional and recycled materials. Typical earth-sheltered or underground houses are characterized by an ‘earth berm,’ which surrounds 1-3 sides of the building.
The primary advantage of living in an earth-sheltered house is the effect of passive heating and cooling that the earth berm has on the living space. Earth-sheltered homes are generally constructed with a south-facing orientation in order to maximize solar exposure for both power generation and heat collection purposes. The characteristic earth berm, which surrounds the exterior of the living space, effectively acts as both insulation and a temperature regulation medium for the building. In other words, the thermal mass of the earth berm absorbs and stores heat during the summer months (leaving the living space cooler) and releases that stored heat into the living space during the winter. This is only one form of passive heating and cooling. Other methods involve controlling airflow through overall architectural design and by window and ventilation configuration.
Arguably the most well-known and functionally reliable earth-sheltered homes are the Earthships of Taos, New Mexico. The Earthship is the brain-child of architect Michael Reynolds, who first developed and tested the idea in the early 1970s. Reynolds’ brand of passive design is now termed ‘biotecture,’ a category of architecture defined by its consideration for efficiency, ecology, life systems, and natural processes. Essentially Earthship Biotecture is an all-encompassing trade of building and design techniques in the world of permaculture and ‘green’, ‘eco’ and sustainable home design. The Earthship strives for (and arguably revolutionizes) full off-grid autonomy by (1) generating its own electricity using solar and wind power, (2) regulating its own temperature and humidity by utilizing multiple passive HVAC methods, (3) harvesting its own water and using water 4 times more efficiently than traditional homes, (5) featuring its own indoor greenhouse, and (6) treating its own sewage by adding outdoor botanical cells to a conventional septic system.
Among the most unique aspects of the Earthships is the trademark use of tires as both an important structural component and (remarkably efficient) insulation material. The tires are filled with compacted dirt, or “rammed-earth.” Each earth-rammed tire serves as a building unit (essentially a large, rubber brick) for the earth berm, and as a large block of thermal mass that absorbs, stores and releases heat energy. Materials such as straw bale, cans, bottles and other recycled materials are also commonly used as insulation or to form a matrix to maximize the structural integrity of concrete walls.
For plans, designs and other information on Earthships visit www.earthship.com