Spatial Sustainability in Cities Organic Patterns and Sustainable Forms

Because the complexity of cities seems to defy description, planners and urban designers have always been forced to work with simplified concepts of the city. Drawn from natural language, these concepts emphasize clear hierarchies, regular geometries and the separation of parts from wholes, all seemingly at variance with the less orderly complexity of most real cities. Such concepts are now dominating the debate about sustainability in cities. Here it is argued that space syntax has now brought to light key underlying structures in the city, which have a direct bearing on sustainability in that they seem to show that the spatial form of the self-organised city, as a foreground network of linked centres at all scales set into a background network of mainly residential space, is already a reflection of the relations between environmental, economic and socio-cultural forces, that is between the three domains of sustainability. Evidence that this is so in all three domains is drawn from recent and new research, and a concept of spatial sustainability is proposed focused on the structure of the primary spatial structure of the city, the street network. Introduction: naive descriptions of the city Ever since the planning and design of towns and cities became a recognized arena for human thought, planners and designers have worked with simplified conceptions of the city. Concepts of orderly hierarchies, regularized geometries, and the separation of parts from wholes, have commonly prevailed and been in striking contrast to the seemingly disorderly complexities of real cities. The reasons were perhaps simple. The complexity of real cities seemed to defy description, so descriptions of the city were shaped by the nearest available concepts and terms in common thought, and these were then turned into design and plans for new cities. In 1965, Christopher Alexander offered a luminous critique of such thinking, in particular locating the origins of hierarchical thinking in the nature of human thought and language itself, with its dependence on well defined classes of things ordered in a more or less hierarchical way (Alexander 1965). The Alexander of 1965 saw that the problem of naïve descriptions of the city needed to be circumvented by arriving at descriptions of the city without, or with the minimum, dependence on language, even though his attempt at a general characterisation of the city as a semi-lattice was less than compelling. With this in mind, it was always a primary aim of space syntax to arrive at spatial descriptions of buildings and cities with the minimum intervention of linguistic concepts. The ultimate model for all such endeavours is of course Euclid, who made the first sciences possible by freeing the descripttion of geometric forms from linguistic baggage and substituting purely formal terms with minimal – and so clearly definable meanings. In this sense space syntax always aimed to be in the first instance a theory of description for the spatial forms of buildings and cities. It aimed to be able to describe, compare and relate the differences between spatial patterns with the minimum of terms with the minimum of meaning. We often described this project as that of making the city and the building speak, rather than speaking on their behalf as we felt other theories had done. We were aiming at what we might call internally derived, rather than externally imposed, descriptions. In the case of cities, one of the principal drivers of the quest for internally derived descriptions was the expectation that they would, through these descriptions, reveal themselves to be (as Alexander