Urban mining in buildings for a circular economy: Planning, process and feasibility prospects

The construction industry remains under immense pressure to reduce its material and climate related impacts. Increasing material demand and reduced building lifetimes have therefore motivated efforts for urban mining in buildings. Even though urban mining has been projected as a crucial measure for improving resource efficiency, its adoption as a practice in the construction industry remains at a very symbolic stage. Upscaling secondary resource recovery and reuse in the construction sector requires further efforts to understand urban mining feasibility from the perspective of project timelines, salvage time, skills and costs. Hence, this study develops an empirical research approach to measure urban mining feasibility and applies it to demolition-ready urban residential buildings stock in Singapore with semi-skilled construction workers. It develops indicators for urban mining feasibility based on planning stages, process change, behavioural practices and reuse-driven economic considerations. Based on urban mining of over 350 building components from 34 categories, results show an average of 1 to 12 min recovery time with an estimated urban mining cost from S$0.8 to S$9 per building component. Further, regulatory requirements for demolition permits can provide sufficient time for urban mining without affecting project timelines. Even though the mining skills of workers seem important, results highlights significant improvement in mining skills based on repeated salvage of specific building components. Results also provide robust evidence of reuse-driven urban mining feasibility in the case under study with significant prospects for embodied carbon savings. Overall, urban mining of buildings can contribute to net-zero targets and climate mitigation efforts with greater multi-stakeholder involvement and market push for reuse in the construction sector.