Material flows and in-use stocks of durable goods in Chinese urban household sector

Households are basic units of final consumption and huge reservoirs of in-use stocks of durable goods. While most studies on social metabolism were conducted at the aggregate national or city level, household level analysis is lack. In the past three decades, China has witnessed growing urban population, increasing household incomes and tremendously improved living standards. The size of urban household consumption increased 23 fold during 1985-2015. In this study, we established an accounting frame for material metabolism at household level with a focus on in-use stocks of durable goods and bulk materials. Long-term trajectories of stock accumulation of residential buildings, home appliances and transportation tools, as well as associated material inflows and outflows, are investigated. Results show that the stock of residential buildings and most home appliances tended to saturate after rapid growth, but the stock of transportation tools, especially private cars, is still under growth. We estimate that total material stocks amounted to 147 tons per household in 2014, compared to 54 tons in 1981. Residential buildings take the majority of material stocks, accounting for 98.8% of the total. The aggregate material stocks of home appliances increased steadily and the phenomena of inter-product substitution was quite obvious. Material stocks in transportation tools exceeded those in home appliances since 2012 and reached more than 400 kg per household in 2014. Metabolism of durable goods in households is a mirror of physical capital accumulation of urbanization. Product-by-product accounting can provide baseline information for life cycle management of urban material flows.