The Potential of Coupling the Circular Economy and Energy Transition in the Built Environment: A mixed methods study to the potential environmental impact reduction of applying different Circular Economy strategies within Net-Zero Energy Building (NZEB) refurbishment solutions

Abstract

Net-Zero Energy Building (NZEB) refurbishments are proposed as one of the solutions to refurbish the Dutch existing building stock and, thereby, stimulate the (low carbon) Energy Transition within the built environment. Taking into account the increasing share of ‘embodied’ emissions due to the improved operational performance by these solutions becomes important to further improve the sustainability of the built environment. Therefore, the Circular Economy is expected to encourage this by reducing fossil fuel use and greenhouse gas emissions. However, literature is inconclusive regarding the complementarity of these two paradigms. Therefore, this study aims to expand the body of knowledge on implementing Circular Economy strategies within Energy Transition measures by studying whether and how such strategies are already applied within NZEB refurbishments and investigate the potential environmental impact reduction of applying different Circular Economy strategies in these solutions. By using an exploratory sequential mixed methods design, this study first, qualitatively analyzed the application of Circular Economy strategies in NZEB refurbishments within seven construction companies in The Netherlands, through semi-structured interviews. Subsequently, it quantitatively assessed the potential environmental impact reduction of applying different Circular Economy strategies within NZEB refurbishments by using Life Cycle Assessment (LCA) on a case study. Regarding the first, the findings show that despite developments towards Circular Economy implementation are slowly occurring, the Circular Economy and Energy Transition still seem to be two separate worlds. More inter-organizational or strategic collaboration is expected to reduce barriers to implement Circular Economy strategies. Regarding the latter, applying Circular Economy strategies can reduce the environmental impacts of NZEB refurbishments. Especially the use of secondary materials results in the least environmental impacts, however, credits for potential benefits beyond the system boundary are found to be highest by using bio-based materials with energy recovery by wood incineration. Despite this controversial finding, it is expected that different allocation methods would influence the results significantly and that the used cut-off approach from the European CEN standards does not incentivize companies to design for multiple product cycles in light of a Circular Economy. Therefore, besides the use of secondary materials, companies should be encouraged to design products for future use.