Sustainable urbanism: towards a framework for quality and optimal density?

The question of density is closely connected to urbanization and how our cities may evolve in the future. Density and compactness are two closely related but different criteria, both relevant for sustainable urban development and the transformation of cities; however, their relationship is not always well understood. While a high degree of compactness is desirable, too much density can be detrimental to liveability, health and urban well-being.

The purpose of this article is to report first on an extreme case of hyper-density: the Kowloon Walled City (demolished in 1993), where 50,000 residents led a grim life in one of the most densely populated precincts in the world with intolerable sanitary conditions. While the Walled City was a truly mixed-use and extremely compact precinct, it was neither a ‘liveable neighbourhood’ nor sustainable. The article then explores some more recent cases of optimized quality density in developments in Singapore, Sydney and Vancouver. This article sets out to answer the question: Since density is key to sustainable urbanism, what are the drivers and different planning approaches in relation to establishing an optimal density? And what is the ideal density model for tomorrow’s sustainable cities?

Some of the critical thinking around the high-density cases is replicable and could translate to other cities to inform new approaches to quality density. Medium to high-density living is acceptable to residents as long as these developments also provide at the same time an increase in quality green spaces close by. The article explores which density types could help us to create highly liveable, economically vibrant, mixed-use and resilient neighbourhoods of the future. It concludes that every development requires a careful optimization process adapted to the conditions of each site.