System dynamics modeling for construction material flows of urban residential building: A case study of Beijing, China

Rapid urbanization and population agglomeration in cities result in massive construction and replacement of building stock with unceasing material flows that interact with the environment. The large quantities of material consumption and induced construction and demolition (C&D) waste have already led to severe resource and environmental problems in China. In this study, a system dynamic model under STELLA platform, was developed to simulate the urban residential building flow changes and related steel demand as well as C&D waste generation for the city of Beijing from 1949 to 2100. Results show that the residential building flows and related stocks of Beijing city will largely vary under different scenarios. The baseline scenario witnessed the construction flow peak in 2010 and projects that the building stock will saturate in 2059 with a total building floor area of 8.79E+8 m(2), and the largest demolition activity is expected in 2079 with a demolished floor area of 1.65E+7 m(2). Overall cyclical dynamics are observed for construction and demolition flows under middle and long-lifetime scenarios, but not prominent for short-lifetime scenarios. If effective urban mining strategies are implemented, up to 70% of future primary steel demand could be satisfied by recycled steel from C&D waste for baseline scenario. The results obtained in this study illustrate the significant resource and environmental saving potential of prolonging the building lifetime and strengthening recycling practices, and highlight the great need of effective policy intervention for waste management infrastructures planning in advance.