Development of weighting factors in the context of LCIA

A new method is proposed for the identification of environmental impact category weights using a panel approach and a MultiCriteria Decision Aid (MCDA) for use within the weighting step in Life Cycle Impact Assessment (LCIA). Seven environmental criteria were assessed by panellists and weights were obtained. The weighting factors of 10 impact categories were calculated according to a four-step procedure: (1) criteria definition; (2) scoring of each impact category (scale of 1–100, 100 causing the most damage) according to seven environmental criteria (human health, ecosystem health, resource consumption as well as scale, duration, reversibility and “distance-to-target”) by a panel of Canadian citizens; (3) assessment of each criterion's importance using a “resistance to change” approach; and (4) criteria aggregation (through MCDA) which allowed the calculation of a final weighting score for each impact category. The greatest advantage of this procedure is the ease with which it can be implemented in a Life Cycle Assessment (LCA) study whatever the LCIA method is used. Integrating weighting factors specific to the Canadian environmental context into a site-dependant LCIA method will contribute to the progress of LCA in Canada.