Optimization of density regulation under urban transformation: Implications from urban redevelopment in Hong Kong

This paper explores optimized density design from economic, social, and environmental perspectives to facilitate urban redevelopment. Using geo-specific data from Hong Kong, we identify feasible areas for various floor area ratio (FAR) schemes, including on-site density relaxation through density bonus and land-use variance, as well as transfer of development rights (TDR) involving receiving site selection, TDR transactions, and TDR reserve. We develop a spatial equilibrium model that integrates development and redevelopment options to support optimal FAR design. Our simulation reveals that the on-site density bonus can exceed 18 %, suggesting there remains room for further FAR expansion in areas with high feasible density and low existing building heights. In addition, cross-district transferable density bonuses at identified sending sites in Kowloon and Hong Kong Island range from 24 % to 37 %, highlighting the potential to unlock density across various receiving sites while considering developer experience, land bank returns, and market uncertainty. By proposing density schemes and evidence-based policy tools, this paper provides practical insights into the efficient and adaptive development of density regulations for urban planners and policymakers in Hong Kong, with implications that can be generalized to other urban contexts.