Since 1998, Prof. Hiroki TANIKAWA has studied the material weight of human activity, focusing on how much material is consumed in industrial processes. This research looks at society’s “material stock”—all the buildings, roads, cars, and other durable items that rely on constant inflows of resources and produce waste.

To build a sustainable society, reducing accumulated material stock and improving resource efficiency are key goals. Similar to biological metabolism, human society draws in materials from the environment and releases waste. This “social metabolism” involves analyzing the flows and efficiencies of these resources.

The Tanikawa Lab conducts material stock analysis at various scales—city, regional, and global. City-scale studies, for example, use 4D-GIS technology to track material accumulation above and below ground, highlighting areas for recycling. Studies in cities like Wakayama reveal where materials are stored and how long structures typically last.

On a national scale, material stock accounts help decision-makers plan for sustainable growth, while in developing countries, analysis of material needs supports sustainable development goals. For example, in China, forecasts of steel and cement demand help model future resource use and emissions.

The Lab’s work also supports disaster planning by estimating material volumes in damaged areas, useful for planning debris removal and reconstruction efforts. This helps communities recover by understanding the materials needed to restore normal activity.

Find out more about Hiroki Tanikawa's work on https://sd.urban.env.nagoya-u.ac.jp/ensap/en/