Defining sustainability-aimed urban metabolism indicators

The urban metabolism has been advanced as an approach for quantifying energy and resource use and supply in modern societal system. It is a multi-disciplinary research domain focused on providing important insights into the behaviour of cities for the purpose of advancing effective proposals for a more humane and ecologically responsible future. Urban metabolism indicators (UMIs) could play an important role in advancing the science and practice of urban metabolism towards sustainability.
This paper reviews the key concepts of urban metabolism and commonly used indicators for gauging the state and progress of urban metabolism, and discuss how UMIs can be further improved from an urban sustainability perspective. Primarily based on peer-reviewed journal papers, as well as books, and documents published by research institutions, international organizations and governmental agencies, this paper systematically examine what UMIs actually measure and whether they are adequate for gauging urban metabolism, and then discuss major oxymorons and challenges as well as ways forward in developing and implementing UMIs towards sustainability. Numerous UMIs have been developed, including single composite indices and indicator sets. Focusing on the indicators based on two indicator sets (emergy synthesis and material flow analysis), this paper analyses the relationships between these indicators and three dimensions of sustainability (environment, economy, and society). The core aim of this research is to figure out sustainability aimed urban metabolism indicators. In this way, this paper builds the bridge between urban metabolism and urban sustainability which can be a promising method using urban metabolism indicators to measure (assess) urban sustainability.