Interdisciplinary perspectives on environmental appraisal and valuation techniques

Techniques of environmental appraisal and valuation play an important role in the context of sustainability assessment. They are at the heart of methods for quantifying economic and social costs and benefits, as well as the direct ecological impacts that are an inevitable side-effect of material progress. Concepts such as the physical life cycle of products and processes, and the need for clearly defined system boundaries, are key elements in environmental problem-solving. However, some economists would claim that, as a normative discipline, their methods can be extended to incorporate all of society's environmental concerns. In contrast, engineers and environmental professionals have at times argued that economic techniques (such as costbenefit analyses) may well obscure the impacts of different courses of action, and that decision makers consequently become less well informed rather than the reverse. Aggregate decision criteria, for example, often conceal the weighing of various impacts. By contrast, the sort of prescriptive analytical tools emanating from engineering and the physical sciences can provide alternative insights that complement those that spring from economics. These include thermodynamic (energy and exergy) analysis and environmental life-cycle assessment. A range of interrelated environmental project appraisal techniques is therefore examined in order to determine their relative merits. Practical examples involving resource (energy and hydraulic oil) use, pollutant emissions, and waste disposal and recycling (of hydraulic oils) indicate that many of these methods can play an important evaluative role as part of an interdisciplinary toolkit within a general systems framework. Nevertheless, caution needs to be used when adopting economic and engineering analysis techniques so as to ensure that they are fit for their sustainability purpose.