Comparative vs. Absolute Performance Assessment with Environmental Sustainability Metrics

Different goals and potential audiences determine that two types of environmental performance assessments (comparative vs. absolute) can be distinguished. Whether sitespecific environmental conditions are accounted for constitutes an underlying watershed between them. As a result, disparate metrics are needed to accommodate these different assessments, which essentially demand “realism” to different extents. In the context of sustainability, the dilemma of pursuing “relative” or “actual” environmental outcomes is getting more prominent. A four-class scheme is proposed for classifying metrics in such a manner that appropriate metrics for either comparative or absolute assessment can be identified, respectively. Discussion is also given to the metrics of each class, in terms of their different characteristics and utilization.