Choosing green materials requires considerable time and costs – on average 20% more. Cradle to Cradle perspective gives the best account of the material – what it is made of, where it is from, how much energy to make and transport, how it functions in the house and whether or not it can be reused afterwards.
The ideal material is totally natural, has low-embodied energy, is easy to work with and lasts a long time. Clay from the site for your core structure is about as green as it gets. Take advantage of your local resources, put pressure on your builders’ merchants to supply healthy alternatives and cut down on the packaging & waste. There are red lists and green lists which make it easier to know what to avoid and good alternatives.
Cement lasts a long time but is responsible for 11% of C02 emissions. Hard to avoid when building a house, less is best.
Wood is really sustainable in NZ. The treatment for rot can be very toxic, avoid CCA. There are better treatments and species which are naturally rot-resistant.
Wool has high UV protection and is a renewable, fire retardant, biodegradable, durable, elastic and natural insulator.
Enviroboard can be made from straw. Construction panels, like enviroboard, built from agricultural wastes, have been around for hundreds of years, especially in Central and Eastern Europe where pressed leaves and straw were used as insulation and even structural material.
Strawblocks are strawbales that have been recompressed to the density of wood blocks. This makes them more efficient to transport and also add strength and solidity to load-bearing walls.
Adobe / Clay – At least half of the world’s population live or work in a building made with clay as an essential part of its load-bearing structure. Many natural building techniques use clay as a primary material. Adobe, cob, cordwood, and rammed earth structures all use clay as well as building elements such as floors and renders. It has great thermal properties.