EMBODIED ENERGY

Buildings not only use energy, it also takes energy to make them. This is 'embodied' energy, which is all the energy required to extract, manufacture and transport a building's materials as well as that required to assemble and 'finish' it. As buildings become increasingly energy efficient, the energy required to create them becomes proportionately more significant in relation to that required to run them. This is particularly true because some modern materials, such as aluminum, consume vast amounts of energy in their manufacture. The common building material with least embodied energy is wood, with about 640 kilowatt-hours per ton (most of it consumed by the industrial drying process, and some in the manufacture of and impregnation with preservatives). Hence the greenest building material is wood from sustainably managed forests. Brick is the material with the next lowest amount of embodied energy, 4 times (X) that of wood, then concrete (5 X), plastic (6X), glass (14X), steel (24X) and aluminum (126X). A building with a high proportion of aluminum components can hardly be green when considered from the perspective of total life cycle costing, no matter how energy-efficient it might be. From the perspective of embodied energy, every building, no matter what its condition, has a large amount of energy locked into it. This is yet another factor in favor of conserving and restoring old buildings, and for designing long life, loose fit buildings that easily accommodate change. Also, because the energy used in transporting its materials becomes part a building's embodied energy, this is an incentive to use local materials, thus helping the building to be embedded in place.

Buildings: Mont Cenis Training Center, Slateford Green, University of Nottingham Jubilee Campus, Cotulla Ranch House, Howard House, Palmer House, Westcott/Lahar House