Revisiting the relationship between sustainable development and industrial ecology

The concept of industrial ecology (IE) follows the ideal of environmental balanced industrial complexes and perceives an industrial system not apart from its surrounding systems but in interaction with them. The methodological consequence of this assertion is to investigate the flows of materials and energy in industrial cycles and consumer activities, the effects of these flows on the environment and how they are influenced by economic, political, regulatory and social factors, in order to evaluate and, finally, to optimize these flows. Industrial ecology has been developed by engineers and thus the claim for scientific objectivity is strong. Considering political and social factors implies, however, to reflect about changes of operations and attitudes. Therefore one might ask about a methodological connection of engineering skills with political and ethical reasoning. This paper has the objective to argue for such a connection in some domains of industrial ecology. The presumption for the value of this endeavour is that IE has a normative potential for the design of a possible sustainable world, which stands next to its advanced technological features. In order to argue for a methodological connection between analytical and argumentative skills, section two and three of this paper will examine sustainable development as a framework for IE and discuss the theoretical basis of the IE concept. Section four and five analyse industrial metabolism as a core principle of IE and discuss IE tools and applications. The sixth section associates empirical and normative elements in IE with help of two domains and three different application levels and exemplifies the possibility for interdisciplinary cooperation within the field. The goal of this association is to make clear that the question today is no longer: Is IE is an objective science or not, but rather: how to assemble methods from the "two cultures" in the most beneficial manner?