Retrospective carbon reduction potential of residential buildings in China based on equity and efficiency coupling

Carbon dioxide (CO2) mitigation in the residential building sector has become critical for China in achieving its carbon peak and neutrality goals. This study is the first to retrospect the historical carbon reduction potential in China's 30 provinces by establishing an equity and efficiency coupling model and comparing the differences in carbon reduction potential under three scenarios: equity priority, efficiency priority scenario, and balance equity with efficiency. The core findings of this study reveal that: (1) China's total CO2 emissions in residential buildings increased from 975.67 Mt to 1328.47 Mt during 2010–2020, where the provinces with the highest CO2 emissions are Shandong, Hebei, and Henan; energy intensity and energy carbon emission coefficient are the most critical driving factors affecting the CO2 emission, followed by floor area per capita and population size. (2) The carbon reduction potential index of residential buildings in eastern provinces is generally higher than that in western provinces; the growth rate of carbon reduction potential is the fastest under the equity priority scenario, and Beijing, Shanghai, and Inner Mongolia have the highest carbon reduction potential. (3) The provinces gradually enter a strong coupling status associated with the climate zones of residential buildings, while the coupling status of the urban area is higher than that of the rural area. Overall, this study adopts a new coupling perspective of equity and efficiency, where the proposed assessment model serves as a reference for measuring the retrospective CO2 mitigation effect in residential buildings in other countries.