Development of a Structural Path Analysis Method for Supply Chains Using Multi-Regional Input–Output Tables: A Case Study of the Japanese Construction Industry

Abstract

Recently, supply chains have become more complex and diverse due to globalization, making it more difficult to identify the sources of environmental impact. It has become necessary to consider the responsibility for indirect emissions from Scope 3.　 This paper focused on the Japanese construction industry, which had a high ratio of indirect emissions and has been affected by the rising cost of materials and attempt to clarify the entire picture of the long and complex supply chain of the Japanese construction industry by the I-O analysis. For this purpose, it developed two methods: one is to analyze supply chains at higher stages in a short time, which was difficult with existing methods, and the other is to eliminate routes that deviate from the reality of the supply chain and derive only valid routes. By analyzing the supply chain by path using these methods, it found that the Japanese pig iron industry plays a central role downstream in the supply chain of the Japanese non-timber non-housing construction industry, and that there are many overseas oil and iron ore mining industries further downstream. It was possible to suggest the possibility of reducing CO2 emissions by changing the source of raw material imports.