Assessing cities: a new system of cross-scale spatial indicators

Urban stakeholders require quantitative and robust tools to implement new paths to urban sustainability. Urban form, the spatial distribution of activities and urban organization are crucial aspects of cities' sustainability. Many tools and assessment systems have been developed to improve cities' energy efficiency and environmental footprint. However, most of these tools are based on the building scale. Most urban stakeholders are now convinced that a building scale approach is not sufficient: the scale of analysis should evolve from the building to the neighbourhood, district and city scales. An innovative system of indicators is presented that answers the need for multi-scale and cross-scale indicators and encompasses the intrinsic complexity of the city. Based on a morphologic approach, new mathematical formulas are used to generate urban sustainability indicators. These indicators can assist with the comparison of urban projects by using a structural point of view to assess the energy efficiency, social and environmental consequences of different urban forms. A comprehensive table displays 60 indicators and methods to quantify them. Some of these indicators have been quantified for real cities and are presented.