Inclusion of prevention scenarios in LCA of construction waste management

Abstract

PURPOSE: Life-Cycle Assessment (LCA) has been applied extensively for the environmental evaluation of solid waste management. However, there is a lack of approaches based on the LCA perspective to deal with waste prevention, which constitutes the first and overriding principle of waste management hierarchy, both in relation to solid waste in general and to construction waste (CW) in particular. This paper explores the possibilities of the LCA for the evaluation of CW management that include prevention activities. METHODS: The functional unit and system boundaries used in the traditional LCA of CW management are redefined to include prevention scenarios; this leads to two methodological options (Options 1 and 2). From the above, general and simplified models were developed to compare non-prevention with prevention scenarios. The general model evaluates CW management scenarios that consider several CW fractions, while the simplified model is applicable to the analysis of one separated CW fraction. A case study was carried out on new buildings in Spain. Optimization and replacement measures of prevention were developed and four CW management scenarios were compared using the general model. The simplified model was applied to the management of 1 tonne of concrete waste. RESULTS AND DISCUSSION: The impact category of climate change was evaluated. Prevention was the most favourable scenario, since, in addition to reducing the amount of CW generated it also reduced CO2 emissions. Regarding the usefulness of each methodological option, Option 1 is more suitable for those LCAs that are aimed towards helping in the decision-making process regarding preventive measures during the design phase, as it enables the actual impact of CW to be monitored in construction work, a building element, or a separate fraction. However, Option 2 facilitates the interpretation of those loads saved by means of not generating CW in prevention scenarios, and this option is hence more useful in LCAs whose objective is the selection of the optimal type of CW management. CONCLUSIONS: Most CW prevention studies in the reviewed literature are focused on the reduction of the quantities of waste. The methodological approaches in this study allow a greater insight into the effects of prevented CW on the environment. The proposed models could support the preparation of national waste programs, and could serve as an instrumental tool to simulate the environmental impacts of CW management scenarios that include waste prevention.