System Dynamics-Life Cycle Assessment Causal Loop Model for Evaluating the Carbon Emissions of Building Refurbishment Construction and Demolition Waste

Purpose: Building refurbishment (BR) is promoted as a green alternative to demolition and new build for urban renewal. The construction and demolition (C&D) waste of BR is increasing and recognized as more complex to manage. To address the limitations of the current static and linear life cycle assessment (LCA) method for evaluating the environmental impact of C&D waste, this study decodes the complex process and provides a causal loop model for evaluating the carbon emissions (Greenhouse Gases emissions) of BR C&D waste. Methods: The study integrates system dynamics (SD) and a LCA approach to produce an integrated and holistic model for evaluating the carbon emissions of BR C&D waste. The environmental assessment system boundary and main factors of evaluating the carbon emissions of BR C&D waste are identified based on a LCA approach. Stakeholders in the life cycle of BR C&D waste are involved in development of the causal loop model. Semi-structured interviews are conducted with key stakeholders to validate the factors and identify the key processes of BR C&D waste management through a case study of Suzhou, China. Results: Five causal loops are developed in this study: a general model for evaluating the carbon emissions of the life cycle of BR C&D waste, a sub-model for evaluating carbon emissions of BR C&D waste at the dismantlement stage, a sub-model for evaluating carbon emissions of BR C&D waste at the refurbishment material stage, a sub-model for evaluating carbon emissions of BR C&D waste at the refurbishment construction stage, and a sub-model for evaluating carbon emissions of BR C&D waste at the refurbishment material end of life stage. Conclusion: The integrated SD-LCA causal loop model developed in this study will help decision makers to more clearly visualize and understand the current problems associated with BR C&D waste management and thereby strategically intervene to reduce the carbon emissions in the life cycle of BR C&D waste. Graphical Abstract: [Figure not available: see fulltext.].