A meta-analysis of environmental impacts of building reuse and recycling
Bowen Zheng, Yang Yang, Albert P.C. Chan, Hao Jiang, Zhikang Bao
Abstract
Significant efforts have been made to assess the environmental impacts of building reuse and recycling, involving various life cycle assessment (LCA) methodologies and different types of buildings and materials. Consequently, the conclusions regarding the environmental impacts of building reuse and recycling can vary across studies. This study aims to clarify the environmental benefits of reuse compared to recycling scenarios, as well as the advantages of recycling compared to landfilling scenarios. Separate meta-analyses were conducted based on both partial and full harmonization methods. The partial harmonization aligned the functional unit, system boundary, impact allocation methods, and upstream processes of the shortlisted studies, while the full harmonization method further made inventory data and the life cycle impact assessment method consistent. The results indicate that after the partial harmonization of LCA studies, the environmental impact from reuse scenarios averages 58.2 % of those from recycling scenarios, while the impact from recycling scenarios averages 61.1 % of those from landfilling scenarios. After fully harmonizing LCA studies, these ratios increase to 62.9 % and 73.5 %, respectively. Furthermore, the results reveal that the environmental impacts of reusing mass timber and Design for Disassembly modular buildings account for only about 20 %–50 % of those associated with recycling. This paper represents the first effort to produce generalizable findings regarding the environmental impacts of building reusing and recycling. It provides solid evidence that priority should be given to reuse before recycling. Recommendations are also provided for promoting building reuse and recycling. • A meta-analysis compared the environmental impact of reuse, recycling, and landfilling at the End-of-Life of buildings. • Harmonization methods were applied to eliminate heterogeneity in the LCA methodologies and inventory data. • Recycling building materials reduces Global Warming Potential by around 30 % to 40 % compared to landfilling. • Reusing building components and/or materials reduces Global Warming Potential by about 40 % compared to recycling.