a The number in each cell corresponds to the relevant question set for that cell, as outlined in the Appendix.
est impact, a very negative evaluation) to 4 (lowest impact, an exemplary evaluation). The ERF rating is the sum of the matrix element values. Because there are 25 matrix elements, the best facility rating is 100.
In arriving at an individual matrix element assessment, or in offering advice to managers seeking to improve the rating of a particular matrix, the assessor uses detailed checklists and special evaluation techniques. Many checklist items will be common to all facilities, whereas others will be specific to the activity of the particular facility. An illustrative ERF checklist system for a generic manufacturing facility appears as an appendix to this paper.
The assignment of discrete values from zero to 4 for each matrix element assumes that the DFE implications of each element are equally important. The utility of the assessment might be increased by applying weighting factors to the matrix elements, although this may also increase the complexity of the task. For example, if global warming impacts of a facility's operations were judged to outweigh the localized impacts of liquid residues, weighting of the "energy use" column could be increased and that of the "liquid residue" column correspondingly decreased. When comparing facilities or assessments with one another, of course, identical weighting factors must be used.
This system is deliberately semiquantitative to respond to the conundrum that has often bedeviled attempts to develop workable DFE/LCA tools. On the one hand, it is extremely difficult—many professionals would say impossible—to quantify the impacts of even those environmental releases and effects that can be inventoried. For example, how should one quantitatively evaluate the tradeoffs between using a substance with a highly uncertain potential for human carcinogenicity and one tied to possible loss of biodiversity? (What is the value of a