" although it is possible to survive with pre-industrial technology, this is not what is proposed."

YOUR HOUSE IS ALIVE it's biodynamic and you're part of the organism!

form, fabric, orientation.

A reduction of dependency on the non local environment, this means as much as possible, sourcing materials locally, it reduces transport costs, and so lowers the pollution debt and energy debt of the building . Following this, the more energy independant a building, accomplished through energy efficiency, the less pollution debt it will accrue in use, if ventilation, fenestration and insulation are well balanced it can be possible to reduce a buildings ongoing energy needs.

Wood and other natural materials are a relatively environmentally benign source of material for building with.

Passive solar gain can account for a large proportion of required heating energy. Orientation is a prime factor in a greenbuilt structure, if the surfaces don't integrate with available sunlight, then it becomes more difficult to use sunlight as an energy source. The maximum use of the sun as an integral part of the design reduces lighting costs; allow windows to provide the maximum practical amount of natural light and heating (should that be a factor. by angling surfaces toward the sun and exposing any massive construction elements so that they may soak up solar heat and then radiate it as heat at night or store it in an internal or underground heat store. An underground heat store can be accomplished in a number of ways, even a gravel bed. Heat pumps can also be introduced (read the note at page bottom.).

Recycled materials can also be used, not just heavily processed, manufactured products but also raw recycled materials from obsolete structures. Low processed products should always where possible be sourced. Organic and chalk based paints are also on the market but be wary of environmental claims justifying a product of otherwise dubious quality. Energy efficiency is a very important aspect of greenbuilding to consider, a building (in Britain) should be well insulated, to as much as 30cm (extreme) or so and double or even triple glazing should probably be used, with low emissivity glass. "Hemp Isovanchre" (a French product made from hemp) and "Warmcell" (recycled newspaper) are environmentally sound insulating materials.

It is helpfull, when considering green building, to remember the saying of Le Corbusier "houses are machines for living in", if only because the design possibilities are often hardly considered in the face of normal or traditional practice. For instance the sphere is much more efficient at containing it's energy than any cuboid as there is less surface area in relation to cubic capacity through which useable energy might escape.

Energy content and pollution debt of materials is not widely costed by materials suppliers and manufacturers, your supplier probably won't even be familiar with such concepts so knowing the score for yourself is essential if you are considering building with this in mind.

Finally the health of occupants should be of utmost priority, a building should be responsive to and controllable by it's occupants, breathability in a building is another important health factor for both the building and it's occupants. Air should flow through and not be trapped within a building, a building should be a comfortable, hospitable environment to be part of.

Warmcell, Excell ltd. 13 Rassau st. Ebbw Vale, Gwent NP3 5SP, 01495 350 655.

CAT are an excellent source of books on htis subject, Machynlleth, Powys SY20 9AZ. tel 01654 702 400

Heat pumps can also be introduced (your fridge is a heat pump). There are many different types in use, for instance swimming pools are commonly heated from air using heat exchangers. The Royal Festival Hall in London is heated by the river Thames. It is, using this technology possible to recover heat from waste water (your bath, etc). Heat pumps work by extracting energy from waste or external sources and can do so from a very low temperature source, driven by an electric pump. A stream or bore hole is a typical energy source, often even in winter. The vapour compression cycle (electric) heat pump, is a closed system around which a refrigerant flows, Extracting energy from a low grade source is done by cooling a gas to a lower temperature than that source, compressing the gas, this is where the electricity is added for pumping, the pressurised gas then passes thru coils in an air or water, etc. medium where the heat is transfered to a cooler environment then giving up it's heat. Expensive in terms of capital cost, not widely used in Britain, though apparently used in U.S.. as heating/airconditioners.