Embodied energy

The embodied energy of a material refers to the energy used to extract, process and refine it before use in product manufacture. Therefore, a correlation exists between the number and type of processing steps and the embodied energy of materials. For example, the fewer and simpler the extraction, processing and refining steps involved in a material's production, the lower its embodied energy. The embodied energy of a material is often reflected in its price.

In some cases, the most technically appropriate material will lower energy costs over the life cycle of a product. For example, composite materials involving carbon fibres or ceramic compounds may have a relatively high embodied energy, but when they are used appropriately, they can save energy in a product's use-phase due to their advanced physical properties, e.g., strength, stiffness, heat or wear resistance.

On the other hand, materials with less embodied energy may often be substituted without a loss in product performance, if you optimize the use of the material with respect to the product's reliability/durability and technical/aesthetic functions. (Source: http://dfe-sce.nrc-cnrc.gc.ca/dfestra/dfestra3/dfestra3_3_e.html, September 2004)

Embodied energy in building design

The concept of ‘embodied energy’ originates from designing more sustainable buildings. 

Embodied energy is a significant component of the lifecycle impact of buildings.  Every building is a complex combination of many processed materials, each of which contributes to the building's total embodied energy. Renovation and maintenance also add to the embodied energy over a building's life.

It was thought until recently that the embodied energy content of a building was small compared to the energy used in operating the building over its life. Most effort was therefore put into reducing operating energy by improving the energy efficiency of the building envelope. Research has shown that this is not always the case. Embodied energy can be the equivalent of many years of operational energy.  The single most important factor in reducing the impact of embodied energy is to design long life, durable and adaptable buildings. (Source: Greenhouse, September 2004)

For a list of low embodied energy building materials click here