Exploring urban building space provision and inequality: A three-dimensional perspective on Chinese cities toward sustainable development goals

Accelerated urbanization and population expansion present substantial pressures on the built environment, particularly in terms of inadequate space and pronounced inequality of building provision. A comprehensive understanding of building space provision and inequality of city remains constrained. This study utilizes high-quality building structure data and fine-scale gridded population product to investigate the building space provision and inequality across 67 Chinese cities from a three-dimensional (3-D) perspective. We integrate both dimensions of building space provision and inequality to facilitate a more nuanced understanding of the built environment. With an overall average building volume per capita (perBV: 517.67 m3 /person) and Gini measures (BV-Gini: 0.497), our study reveals that tier-1 cities suffer shortage of building space, while rapidly developing tier-2 cities are confronted with high degree of inequality. The results indicate that urban areas are characterized by a more limited building space provision (perBV: 1,074.52m3/person for rural, and 500.83 m3/person for urban) and higher inequality (BV-Gini: 0.494 for urban, and 0.427 for rural) compared to rural areas. This study provides valuable insights into comprehension of the built environment from 3-D building perspective toward achieving adequate and equitable building space, consistent with the Sustainable Development Goals (SDGs) and the principles of New Urban Agenda.