Tracing high-sustainability performers among world cities - design and application of a multi-temporal data envelopment analysis

Sustainability performance is nowadays a major challenge for many cities in the world. Sustainable development refers to the achievement of both ecological and socio-economic objectives over a relevant time period. The present study aims to trace the relative sustainability status of 39 world cities included in the so-called Global City Power Index (GPCI) of the Mori Memorial Foundation in Japan. This is a unique large-scale and detailed multi-temporal data base containing approx. 80 systematically collected urban indicators for the cities concerned. This paper presents and applies a novel and advanced assessment methodology for sustainable and efficient performance strategies of these 39 global cities, by means of an extended and multi-temporal version of a Data Envelopment Analysis (DEA). Using this novel approach, our study seeks to arrive at an unambiguous ranking of the highest performers among 'urban sustainability champions', during the time period 2012-2015. Based on the DEA efficiency assessment by regarding the urban input-output ratio as a performance indicator, we examine here one input indicator (Total Employees) and four sustainability output indicators (CO2 Emissions, Nominal GDP, Level of Satisfaction of Employees with their Lives, and Percentage of Renewable Energy Used). Our empirical results provide a global sustainability ranking of the cities concerned. We also show that many European cities have a relatively high performance score on the human and urban environment. We present next more detailed information on a selection of a few interesting cities. Our approach appears to be able to address realistic and transparant priorities and complex policy choices aiming at an improvement of relatively inefficient world cities.