  The building sector is the largest emitter globally and as such is at the
forefront of the net-zero emissions pathway. 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 global residential building operations and commercial building
operation simultaneously over the last two decades. The results reveal that (1)
the average carbon intensity of global commercial building operations has
maintained an annual decline of 1.94% since 2000, and emission factors and
industrial structures were generally the key to decarbonizing commercial
building operations; (2) 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; and (3) the total decarbonization of commercial building
operations and residential buildings worldwide was 230.28 and 338.1 mega-tons
of carbon dioxide per yr, respectively, with a decarbonization efficiency of
10.05% and 9.4%. Overall, this study assesses the global historical progress in
decarbonizing global building operations and closes the relevant gap, and it
helps plan the stepwise carbon neutral pathway of future global buildings by
the mid-century.
