Unravelling the mystery of Chinese building lifetime: A calibration and verification based on dynamic material flow analysis

Building lifetime is a crucial parameter for modelling building stock's turnovers and related dynamics of embodied and operational energy demand. However, it is poorly characterized and often based on assumptions (especially for developing countries such as China), because no or few empirical data are available. Here we combined a top-down dynamic material flow analysis method with bottom-up information (i.e., age profile of residential building stock, per capita residential floor area, and population) to calibrate the lifetimes of Chinese buildings from 1950 to 2015. We contrasted the top-down estimates with existing literature and primary data from on-site surveys to verify the plausibility of calibrated building lifetimes. We found an overall downward trend of building lifetimes during 1950-1989 and a gradual climb-up since 1990s. However, the present Chinese building lifetime appears still far below the design lifetime (50 years). Up to 2015, the floor areas of Chinese building stock has reached an enormous level of 64.7 billion m(2); on the per capita basis, it has reached 30.5 and 15.7 m(2) for residential and non-residential use, respectively. The yearly demolished floor areas have reached at a level of 1.6 billion m(2). The improved building lifetimes can enhance our understanding of building stock's turnovers and vintage-based energy performance and thus help better characterize life cycle energy demand of building stocks and beyond. To further the use of the calibrated building lifetimes, modelers and data users should also be aware of the variable building lifetimes and have a structured overview of data sources and their inconsistency.