Measures of Sustainability
Overview / Embodied Energy / Operating Energy / Exergy / Durability / Externalities / Ecological Footprint / Eco-Labeling / Life Cycle Assessment

Overview
Measures of sustainability attempt to describe the negative impacts, or conversely the goodness of fit, between human activities or interventions, ecology and the environment. Measures vary between disciplines and those used in economics, for example, may be quite different from others used in areas such as sociology. For architecture, several useful measures have been developed by researchers, and the simpler measures are then often combined into composite measures which attempt to more fully assess the sustainability of architectural intervention.

At present the most commonly available simple (less complex) measures include:

· Embodied Energy
· Operating Energy
· Exergy (Absolute Energy Efficiency)
· Durability
· Externalities

These five measures provide valuable insights into the environmental impacts associated with human activities, and become useful components in the following multi-dimensional measures of sustainability:

· Ecological Footprint
· Eco-Labeling
· Life Cycle Assessment (LCA)

The terms "simpler" and "multi-dimensional" are relative to the complexity of the measures, and it is important to recognize that even the simplest of measures involve considerable effort and scientific sophistication. These aspects can be more fully appreciated by reviewing each of the above measures and their associated limitations.

The next section deals with Embodied Energy in building materials.