Methodological framework of sustainability assessment in City Sustainability Index (CSI): A concept of constraint and maximisation indicators

• This paper presents a framework for the assessment of the City Sustainability Index.
• The assessment of city sustainability must consider constraint indicators and maximisation indicators.
• Constraint indicators relate to limits imposed by environmental sustainability and socio-economic equity.
• Maximisation indicators apply to socio-economic benefits that cities create.
• Five expressive forms for evaluating city sustainability are provided.

This paper presents a framework of City Sustainability Index (CSI) incorporating indicators in the environmental, economic and social dimensions. We define a sustainable city as the spatial entity that maximises the benefits in economic and social dimensions under relevant constraints on environmental limitations and socio-economic distributional equity. Based on the definition, we provide five expressive forms as a framework for judging city sustainability, using a concept of two types of indicators: constraint and maximisation indicators. Constraint indicators judge sustainability of cities based on relevant criteria in terms of environmental sustainability and socio-economic distributional justice. Maximisation indicators measure the benefits cities produce in economic and social aspects. Indicators in the three dimensions – environmental, economic and social indicators – can be categorised into the two types of indicators. In conclusion, we need to assess the two dimensions of cities – limitations and benefits – independently without offsetting one against the other in terms of strong sustainability.