Recycling potential of secondary resources in built environment stocks: Evidence from Hong Kong public rental housing

In urban environments, region-specific knowledge of building material intensities and stocks is vital for efficient resource recovery in the construction sector, especially for city regeneration and redevelopment. Previous studies often relied on generalized data, leading to inaccuracies due to local variations in construction practices, materials, and urban density. This study addresses these limitations by developing a locally refined inventory through a GIS-based, bottom-up material stock analysis that integrates archetype-specific building design data, demonstrated with evidence from Hong Kong's public rental housing (PRH). The results show that material intensities for Hong Kong PRH buildings range from 1567 to 2386 kg/m², with a total stock of 60.85 megatons as of 2022. Up to 46.95 megatons may have recycling potential over the next three decades, offering significant opportunities for sustainable resource management. Spatiotemporal and hotspot identification reveals a shift in material stock distribution toward the northern territories, reflecting urban development trends. This research enhances the accuracy of material stock assessments and supports strategic planning for achieving a circular economy, particularly in densely populated areas like Hong Kong. By promoting circular and generative city concepts and establishing benchmark archives for key construction materials, the study advances practical applications for sustainable urban resource management, aiding policy development for efficient spatial planning and urban mining strategies.