A century-scale dynamic modeling of demolition waste metabolism and associated global warming impact in China's urban residential sector

This paper quantifies demolition waste (DW) from urban residential buildings (URB) in China from 1970 to 2070 under low, medium, and long-lifespan scenarios, as well as the associated global warming impact, quantified as global warming potential (GWP), from DW disposal and avoided through material reproduction under low, medium, and high-recycling rate scenarios. First, DW generation of key construction materials is quantified as a metabolic outflow of URB stocks under alternative building lifespan scenarios. These metabolic flows are then dynamically projected to assess the associated GWP under different recycling rate scenarios. The results indicate that population size and per capita floor area significantly influence URB stock, and that a decline in population leads to a delayed reduction in stock due to system inertia. Longer building lifespans result in slower turnover, increasing cumulative stock, and affecting the timing and magnitude of peak residential stock. The total DW by 2070 is projected to be one-third lower in the long-lifespan scenario compared to the short-lifespan scenario, with 6,577.10 Mt, 13,488.35 Mt, and 20,271.66 Mt in the long, medium, and short-lifespan scenarios, respectively. In the high-recycling rate scenario, GWP becomes negative, with net savings of 27.64 TgCO₂e in the short-lifespan scenario, 18.95 TgCO₂e in the medium-lifespan scenario, and 9.55 TgCO₂e in the long-lifespan scenario. Extending building lifespans and increasing recycling rates markedly reduce both DW generation and associated GWP, with steel and brick offering the highest GWP reduction potential through enhanced recycling practices.