Building-Stock Turnover Reshapes Mitigation Priorities in China’s Building Sector

China’s building sector is pivotal to the 2060 carbon-neutrality ambition, yet prospective assessments often insufficiently capture regional heterogeneity and life-cycle emission dynamics. Here, we develop a provincial-level dynamic framework integrating material flow analysis, life-cycle assessment, and machine-learning-informed parameter trajectories to project emissions through 2060. Under a business-as-usual (BAU) scenario, China’s building life-cycle emissions are projected to peak in 2031–2033, while carbon neutrality remains challenged by persistent pressures from both material use and building operations. These pressures arise from the existing stock, whose continued use sustains energy demand while increasing building retirements shift construction from stock growth to the replacement of retired buildings. Implementing a high-efficiency scenario with regionally differentiated deployment of material- and energy-efficiency strategies could reduce China’s building-sector life-cycle emissions by 90% in 2060 relative to the BAU scenario. Provincial analysis further reveals that similar overall mitigation potential masks substantial differences in the composition of effective mitigation portfolios, reflecting local building-stock and energy-use characteristics. To close the remaining gap, deeper operational decarbonization should be coupled with stock-management strategies that extend building lifetimes, avoid premature demolition, and prioritize renovation and reuse.