Global transition of operational carbon in residential buildings since the millennium

The residential sector is the third-largest energy consumer and emitter globally and as such is at the forefront of the energy transition and net-zero emissions pathway. To accelerate the pace of decarbonization of residential buildings, this study is the first to present a bottom-up assessment framework integrated with the decomposing structural decomposition method to evaluate the emission patterns and decarbonization process of residential building operations in 56 countries spanning 12 regions worldwide from 2000 to 2020. The results show that (1) the operational carbon intensity of global residential buildings has maintained an annual decline of 1.2% over the past two decades, and energy intensity and average household size have been key to this decarbonization; (2) end uses have held an increasingly important role in decarbonizing global residential buildings (-46.3 kgs of carbon dioxide per household per year), with the largest contributors being appliances(38.3%), followed by space heating (21.2%) and lighting (12.6%); and (3) although the total decarbonization of global residential buildings was 7.1 gigatons of carbon dioxide and achieved a decarbonization efficiency of 9.4% per yr during this time period, regional decarbonization inequality and uneven distribution remained quite large, especially in emerging economy regions. Moreover, the uncertainty and robustness of the assessment framework are also tested, and adaptive high decarbonization strategies are further proposed for global residential buildings. Overall, this study reviews and compares global and regional performances and motivations for decarbonization to support national decarbonization efforts to reach net-zero emissions and advance the global residential building sector toward a carbon-free century.