The evolution and decoupling of in-use stocks in Beijing

Environmental problems have become increasingly serious, with the exploitation of global resources, accelerated by increasing population, economy and the expansion of the built environment. Understanding in-use stocks can help alleviate urban environmental problems, for it describes the exchange, storage and transformation of re-sources between environment and city, which is the key to urban sustainable development. This study estimates the historical evolution of Beijing's in-use stocks by bottom-up analysis for 19 sub-types and 117 end-products, including buildings, infrastructures, equipment, vehicles, and consumer durables. And this study explores the decoupling of in-use stocks and economic development using the constructed LMDI-Tapio model and identifies the decoupling mechanism of in-use stocks and economic development. Results of bottom-up analysis demon-strate that, during 1949-2019, in-use stocks expanded almost 80-fold, increasing from 33.92Tg to 2750.30Tg. Buildings stocks take the majority of in-use stocks (79.28%) and non-metallic stocks are the largest category (95.54%). Results of LMDI-Tapio show that the in-use stocks and economic development are still in Weak-decoupling. Economic growth (179.53%) and population (32.20%) affect decoupling negatively impacts. Technology (111.73%) can promote the decoupling, but it still needs to be improved. The technological effect is less than the economic effect, but it can have an impact faster. To achieve the sustainability of the decoupling of in-use stocks, the government can improve the technology while optimizing economic growth.