3.1. Review of the History of Sustainability in Urbanism
Looking back in time, sustainability has not always been a central theme in urbanism. ‘The term ‘sustainable urbanism’ encompasses topics of sustainability related to the entire process of city development and management, while sustainable urban design sits somewhere within that. Sustainable urban design is not necessarily a clearly delineated subset of sustainable urbanism, but instead can be thought of as focus area within it that is concentrated around issues of design, while still maintaining strong links to the other realms such as planning, engineering, real estate, and policy [13
]. The famous image of the architect eating the landscape, by Malcolm Wells, illustrates the way urbanism was seen for a long time: as a destroyer of natural values. Girardet [14
] was one of the first to acknowledge the importance of an integrated approach to developing cities in a sustainable way. He connected themes such as looking at cities as ecosystems, the footprint of cities, urban heat islands, and others with urban design schools, such as the garden city movement [15
], the modern city of Le Corbusier [16
], Frank Lloyd Wright’s Broadacre city [17
], and megacities in general [18
]. His pledge for convivial cities, the role of citizens and the local scale, and the attention for health, greening the city, renewable energy and recycling, and sustainable forms of mobility [14
], are still relevant. Since then, many perspectives, visions, and conceptual practices have been developed, each of them taking sustainability into account in the planning and the design of cities. In the last 20 years, a number of theories or ideologies have influenced thinking about (sustainable) urbanism. Scholars such as Farr [20
], acknowledging a strong shift towards integration of ecological analyses in urbanism, Beatley, focusing on ecologically-based land use planning [21
] and integrating nature into urban design and planning [22
], Mostafavi [23
], deliberating on ecological urbanism, Waldheim [24
], launching landscape urbanism in which landscape supplants architecture as the basis of urban design, and Newman et al. [25
], elaborating on the resilience of the city, as well as Duany et al. [26
], proposing an extensive manual on smart growth, and Haas [27
], defining a wide range of principles for planning of sustainable and resilient cities, have all covered ground related to building a framework for sustainable urbanism. However, much of the literature on sustainable urban design still lacks grounds for holistically relating the different aspects of urban design [13
]. Taking these readings as the starting point of thinking, sustainability in urbanism has been divided in seven distinctive periods [2
] which illustrate how the concept of sustainable urbanism has evolved over time.
From the early days when aesthetics were defined by Vitruvius [28
] as not only beautiful (venustas), but also solid (firmitas) and useful (utilitas) [29
], urban sustainability is defined as a multi-layered concept and aesthetics is equally important as economic viability or ecological value, not more or less important [30
]. Sustainability is not similar to environmental quality. A high environmental quality alone does not guarantee a high degree of sustainability. Similarly, an urban environment with a high environmental quality or a high economic value, but without beauty is not considered sustainable either.
After this, periods such as rationalism and conceptualism can be distinguished. Rationalism assumes knowledge will implicitly lead to solutions. An expert planner or the designer ‘who knows it all’ [31
] is required to translate this knowledge into functional urban environments. The shape of the city follows the land use, or ‘form follows function’ [32
], and engineers play an important role in the final outcome of the design process. In this context sustainability becomes a quantifiable aspect and standards and regulations were introduced, such as for clean water, air, and soil. In the conceptualism period, the water system, the soil, and nature are used as layers [33
], an approach that is widely used in the Netherlands [34
]. The abiotic, biotic, and anthropogenic layers shape the landscape. The layers aim to separate different dynamics of use. Where the subsoil is seen as changing extremely slowly, and the networks change at a moderate pace, the occupation patterns can change relatively rapidly. It assumes the occupation patterns are nested in the infrastructure networks, which in turn are embedded in the substrate system [35
]. In the casco-concept, which is based on this thinking, these spatial dynamics are separated [36
]. In the concept called ‘the strategy of the two networks’, higher dynamic uses (traffic, industries, intensive forms of agriculture) are linked to the transportation network and the lower dynamic uses (nature, green, water, residential) to the water network [37
In the negotiatism period, sustainability is seen as a discussable ambition in the planning process. New methods are developed to target sustainability ambitions, such as the DCBA-method [39
], in which every urban design aspect requirement is set for level D to A, D being the highest. Over time, the negotiation process evolved into advanced participatory processes, in which engaged citizens could co-design and co-create [40
] the sustainability of their direct environment [42
]. In these sessions, the wisdom of the crowd [44
] is used to identify future strategies for a sustainable spatial development.
Looking at the city as an ecosystem [45
] is the key of the period in which urban metabolism [46
] defines the city in terms of its flows. When the layer approach is combined with this system’s thinking, a comprehensive model for urban environmental design [51
] emerges. The degree to which the system is able to deal with the flows, or networks of traffic, water, energy, and materials, determines the level of sustainability of the system. The design of the city is based on ways in which depletion of resources and production of waste are reduced, and in which resources can be reused and recycled within the city.
The most recent periods, emergism and anti-fragilism focus on the city as a responsive system, in which self-organisation and the adaptive capacities of complex systems determine urban processes. Emergism takes complexity [52
] as the input for the design of cities [57
]. Self-organisation and emergence are key concepts, and are used to design interventions in the system to achieve certain changes. These concepts are common in nature and can be used in designing future cities and landscapes that are more adaptable [59
]. The designer acts as a facilitator of the process of change, intervening at specific places or times to initiate a change in the system. Approaches such as eco-acupuncture [60
] and Swarm Planning [58
] aim to design small interventions in an existing urban precinct or landscape to transform the area and become more resilient. In order to apply these principles, physical elements in the city or the landscape need to be made moveable [62
] and capable of responding to different paces of change that might occur in the city: fast, slow, or sudden [63
]. In order to adapt to new circumstances urban systems need to become agile [64
]. Rather than only responding to change by coping with it, urban environments can actually become stronger than before through their response to climate events. This concept is called anti-fragility. ‘Ant-fragility is defined as a convex response to a stressor or source of harm (for some range of variation), leading to a positive sensitivity to increase in volatility (or variability, stress, dispersion of outcomes, or uncertainty, what is grouped under the designation “disorder cluster”)’ [65
], and offers interesting opportunities. For instance, if the city can create a stronger flood defence by itself once a flood occurs, the city becomes safer. Anti-fragilism is not a common approach in urbanism yet. However, the current combination of increasing uncertainties and unalterable cityscapes places urban population increasingly at risk. Therefore it is necessary to investigate the solutions anti-fragility might bring to urbanism.
Learning from the history of sustainability in urbanism, several key-concepts stand out. The concepts developed to create sustainable framework with the landscape as a basis, such as the layer approach [34
], the casco-concept [36
], and the Two Networks strategy [37
], have determined much of the work and research being carried out in landscape architecture.
The engagement of communities in the planning and design of urban environment is another key concept which determines the sustainability, support, and acceptance of urban change amongst residents. Recent concepts such as co-design and co-creation allow for a broad spectrum of expertise sets in the design process, which stimulates the development of new and innovative design ideas and new knowledge.
The view of the city as an ecosystem has changed the way we look at urban change and design. The metabolism and design of flows made it possible to discuss the sustainability of the city as a whole, and close the cycles of energy, water, and materials.
More recently, the city is seen as a complex adaptive system and this implies that adaptation and resilience of the city can be discussed as core characteristics. The adaptivity of the city can be influenced through strategic design interventions supporting self-organisation. Adaptation requires creating space to adapt, hence this concept advocates redundancy (‘space for the unknown’) in the urban realm.
A future avenue to increase the strength of the city is to create anti-fragile environments, which grow under influence of external impacts.
These key characteristics derived from the analysis are summarised in Table 1
. They lead to six principles that serve as a basis for design: closing cycles, innovative designs, create space for the unknown, anti-fragility, people’s engagement, and taking the landscape as basis for design. These principles are regarded under the larger comprehensive concepts such as society, complexity, and landscape.