CO2 emission hotspots analysis on supply chains for wooden houses in Japan

Ninety-four percent of CO2 emissions induced by final demand in the global construction sector stem from the supply chain. Therefore, it is necessary to identify the CO2 emission hotspots within the supply chain and implement targeted reduction measures. This study proposed a supply chain clustering approach considering the functional unit of houses and identified CO2 emission hotspots within the supply chain structure of wooden houses, which accounted for approximately 90% of the total housing stock in Japan. We founded that the top ten CO2 emission clusters (i.e., emission hotspots) account for approximately 40% of the carbon footprint (38 t-CO2) of a wooden house. Specifically, the iron and steel cluster, which includes the pig iron and crude steel sectors, and the cement cluster, comprising the cement and ready -mixed concrete sectors, collectively contribute to approximately 75% of the CO2 emissions within the top 10 clusters. Therefore, the reduction of CO2 emissions from these clusters is of paramount importance. Decision-makers should promote renovation and remodeling policies for vacant houses and prioritize the reuse of foundations, predominantly constructed using steel and cement products, to reduce the supply-chain emissions from wooden houses.