Integrating urban metabolism and life cycle assessment to analyse urban sustainability.

• An UM and LCA unified approach to study urban systems. • A survey based on urban subdimensions and complex systems is proposed. • A multi-layer complex network model based on the survey is tested on a case study. In recent decades, the close correlation between urban development and the concept of sustainability has become increasingly evident and important. This is demonstrated by European Union policies concerning EU cities and the United Nations 2030 Agenda for Sustainable Development, including sustainable development goal (SDG) 11: Sustainable cities and communities. In the context of increasing urbanization, it is essential to find innovative methods to manage urban living systems and to establish a standard method for assessing the environmental performance of cities and their infrastructures. A unified and complete methodology for assessing policies for urban sustainability that takes into consideration urban complexity is currently lacking. In this paper, we integrate the Urban Metabolism and Lice Cycle Assessment approach to assess urban sustainability by developing a multi-dimensional measure framework applied to cities. Our aim is to provide a holistic view of the city and unveiling the interconnections among a set of urban dimensions identified by means of an approach based on complex systems science and complex networks. We also propose a specific survey to investigate the city in a multi-dimensional perspective and suggest key indicators based on network centrality measures for investigating and comparing the interconnections among a set of urban dimensions specifically identified (e.g. energy, material, transport). Finally, a case study based on Beijing is considered to show potential applications. [ABSTRACT FROM AUTHOR]