A bioshelter is a solar greenhouse managed as an indoor ecosystem. The word bioshelter was coined by the New Alchemy Institute and solar designers Sean Wellesley-Miller and Day Chahroudi (Todd, J, Todd, N. 1994). The term was created to distinguish their work in greenhouse design and management from twentieth century petro-chemical fuelled monoculture greenhouses.
New Alchemy's pioneering work in ecological design is documented in their published Journals and Reports. In 1976 the Alchemists built the Cape Cod Ark bioshelter and her sister The Prince Edward Island Ark. For the next 15 years the New Alchemy Institute studied and reported on the use of these prototype food producing ecosystems.
The term bioshelter (life-shelter) derives from two points of view. The first is that of ecological architecture. To the building designer, a bioshelter is a cellular design, with the structure and glazing acting as the cell membrane, controlling gas exchanges and energy absorption. The building "takes in" nutrients, gases and energy from the surrounding environment and produces crops and waste for recycling (Todd & Todd). Thermal mass as energy storage relates to sugar molecules in a leaf cell. The plants and animals within the building act as energy processors, recycling nutrients and creating order.
The second point of view is that of the ecological gardener. The bioshelter is managed as an ecosystem. Earle Barnhart (1978) of New Alchemy Institute has compared a bioshelter to a miniature ecosystem. As in a forest, the structure of the bioshelter controls the air temperature and movement, flow of water through the system, evaporation, humidity and other environmental factors. Solar heat is absorbed and stored for later use. Beneficial insects are provided habitat. Gases are exchanged between the animals, insects, micro-organisms, soil and plants. Also like a forest, within the bioshelter are a variety of microclimates. The south wall bed and central beds receive the most direct sunlight. The north wall receives full sun from the autumnal equinox until the spring equinox and is partially shaded through the late spring and summer. The northeast and northwest corners are shaded for a portion of the day, morning and evening, respectively.
In some cases nutrient cycles are developed between fish and plants, and/or poultry and plants. Ecological relationships between pests and their predators are encouraged. The system is controlled by good design and human intelligence to be a shelter for a diverse community of life forms.