species, and is it ethical even to pose such a question?) On the other hand, quantitative systems are a prerequisite for diffusion of DFE methodologies and concepts throughout industry, especially if modifications to business planning and design processes are desired. The ERF matrix system thus explicitly relies on the professional judgment of industrial ecologists, while allowing for standardization of dimensions through common checklists as the state of the art advances and experience is gained. The system provides an easily used management and operational tool, but it does not pretend to greater certainty than the underlying data justify.
The columns of the matrix correspond to the five major classes of environmental concern: ecological impacts, energy use, solid residues, liquid residues, and gaseous residues. Although other categories could no doubt be suggested, these are readily understood and reasonably comprehensive, in keeping with the practical intent of the system. Both local ecological impacts and (if applicable) loss of biodiversity could be included in the first column, for example.
The rows correspond to the life-cycle of a generic facility (modified slightly to fit the manufacturing example we are using). As these are less intuitive (even environmental professionals are not yet familiar with the concept of the life-cycle of a facility), a more detailed description of each life-cycle stage is appropriate.
A significant factor in evaluating the degree of a facility's environmental responsibility is the site selected and the way in which the site is developed. If the facility is an extraction or materials-processing operation (e.g., oil refining or ore smelting), the location will generally be constrained by the need to be proximate to the resource. A manufacturing facility usually requires access to good transportation and a suitable workforce but otherwise may be unconstrained. Service facilities usually must be located near customers. Office buildings may be located virtually anywhere, so long as it is reasonably possible for employees to commute. Housing developments must be located where people want to live. In all cases, it might be possible to refurbish or add new operations to existing facilities, avoiding many of the regulatory difficulties and environmental impacts of establishing a "greenfield" facility site.
Manufacturing plants have traditionally been located in or near urban areas. Such siting has the advantages of drawing on a geographically concentrated workforce and of using existing transportation and utility infrastructures. One problem with urban sites in some countries is that there may be laws that force purchasers of property formerly used for commercial or industrial purposes to assume liability for any environmental damage caused by the previous owner or