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.