Metrics for Sustainable Development [Green Indices]

Francis Clay McMichael

Carnegie Mellon University

Green indices for products and processes are tools to help people make decisions about environmental issues and problems. We are best served by metrics, both qualitative and quantitative, that can help to resolve issues among technology, economics, and environmental regulatory policies. This session will review concepts of ‘environmental indices’ for green design and will present examples of metrics currently in use or proposed. We will illustrate the consequences of using a toxicity-weighted index for evaluation of the US EPA toxic release inventory database in contrast to the use of direct emission and release data.

Environmental indices are useful tools for several audiences. The better indices are linked to answering questions posed by governments, by the public at large, and by private institutions. A green index may be helpful to the communications media for keeping score and reducing complex information to a smaller, more easily retained, chunk of information. A good index should be simple to use, transparent, and expandable across other issues.

Environmental indices are used in labels on products, such as the US EPA ‘miles per gallon’ label for vehicles or the EPA/DOE energy star label for computers. It has been proposed that some materials should be labeled with an index that reports its content of recycled or reused materials. Such an idea, while simple in concept, becomes more complex when choosing a method for its calculation, and more troublesome when the purpose of the index is to evaluate compliance with law or is the basis for assigning an economic penalty.

There is a need for good examples to show how indices have been effective guides or tools for environmental decision-makers. Future work may expand the use of indices to represent more than an inventory of emissions. We optimistically seek opportunities to find indices that are useful to a hierarchy of users from design engineers to senior system managers.