Goal, Scope and Background The primary goal of this paper is to present a LCI modelling approach that allows the inclusion of all three types of impacts. The approach is based on consequential LCA (CLCA) rather than more common attributional LCA (ALCA). In CLCA, system boundaries are expanded in order to include all significantly affected activities. In addition we show how changing from an attributional to a consequential approach alters how the impacts are evaluated, and discuss the applicability of these two distinct approaches to brownfield rehabilitation decision support. The paper is restricted to urban and contaminated brownfields that are the result of industrial use and whose rehabilitation is aimed at allowing residential redevelopment. Main Features The approach is based on an analogy between the open-loop recycling of material resources and brownfield rehabilitation. Brownfield rehabilitation is associated with two functions: (1) managing the legacy of past occupations on the site, analogous to a waste management function, and (2) providing redevelopable land, analogous to a commodity production function. The consequential system is expanded to cover the subsequent occupation life cycle of the brownfield and the effects on the occupation life cycles of other sites. The proposed model quantifies effects on sites competing to supply the same occupation function. Two approaches are proposed to determine the nature of the sites that are affected and to what extent they are affected: the first resembling a closed-loop approximation, and the second based on economic partial-equilibrium models. Results and Conclusions The scope of the CLCA is far more complex than that of the ALCA. It requires additional data that are associated with important sources of uncertainty. It does allow, however, for the inclusion of tertiary impacts, making it suitable for the evaluation of the often cited environmental benefits of reintegrating the site in the economy. In addition, the ALCA methodology seems to be inappropriate to compare brownfield management options that result in different subsequent uses of the site. Since the effects of this fate are included within the scope of CLCA, however, virtually any brownfield management option available to a decision-maker can aptly be compared. The evaluation of primary and secondary impacts also differs when the consequential approach is used rather than the attributional approach. It is impossible to anticipate the effects of these methodological differences on the results based on the qualitative discussion presented in this paper. Perspectives The complexity and uncertainty introduced by switching to a consequential approach is very high: it is therefore recommendable to evaluate the significance in the gain of environmental information in an actual case study to determine if system expansion is recommendable. Such a case study is presented in Part II to this paper.
Coworkers: Tomas Ekvall
Keywords: Attributional LCA (ALCA), Brownfield, Brownfield rehabilitation, consequential LCA (CLCA), contaminated site remediation, open-loop recycling
Report number: A1509
Authors: Pascal Lesage, Tomas Ekvall, Louise Deschênes, Réjean Samoson
Published in: The International Journal of Life Cycle Assessment. Volume 12, Number 6 / September, 2007. http://www.springerlink.com/content/q8401632388j6425/