Abstract
“Sustainable cities” as a singular concept may very well be a utopian vision impossible to realise in a broader sense. In this chapter, we review the literature on urban sustainability highlighting the complexities and trade-offs between and within the 3 Es—ecology, economy and equality. In particular, we focus here on the intra-urban dimensions of density, mobility, the built environment and housing, lifestyle trends and gentrification along with social sustainability issues of crime, homelessness and community. While gains from increased size and density can be had, there are also many outcomes that depend on urban morphology and the consequences of spatial sorting. Positive outcomes generated by density and efficiency may be offset by, for instance, less sustainable construction materials or increased income inequality. In particular, rebound effects are often overlooked. Hence, it often becomes an empirical issue whether the potential for sustainability gains materialise. Furthermore, as assessed from a more holistic 3 Es’ view, where social sustainability is as important as environmental sustainability, the potential of a “sustainable city” may be a victim of trade-offs that are difficult to resolve.