house heating. Residual products not usable in the immediate vicinity, such as fly ash and sludge, are sold for use elsewhere. None of the arrangements were required by law; rather, all were negotiated independently for reasons of better materials prices or avoidance of materials disposal costs. It is probably accurate to refer to this cooperative project as an early model of an industrial ecosystem. The Kalundborg experience provides a model for industrial ecology at the ecopark level, especially where industrial activities occur in close proximity to one another.
Clearly, any facility that generates products or activities that are environmentally inappropriate should not be considered an ERF. Thus, for example, an otherwise environmentally appropriate manufacturing facility that makes widgets whose design does not permit them to be recycled cannot under most circumstances be considered an ERF, regardless of how well designed it is in other aspects. Evaluating this aspect of the ERF will require analysis of the output of the facility, whatever that may be. If the output is a product, the environmentally responsible product matrix system can be used (Graedel and Allenby, 1995).
As with products, it is apparent that, for a facility to be environmentally responsible, its internal processes must also be environmentally responsible. For manu-