Urban resilience: what does it mean?
10 May 2018
Sara Wilkinson clarifies what urban resilience means and what surveyors need to know, in the first of 2 articles on the subject
As a practitioner, you should be familiar with the term ‘sustainable development’. But what does resilience mean, in the context of the built environment generally, and for building surveyors in particular?
Resilience is derived from the Latin resilio, meaning ‘bounce back’, and during the 19th century it became associated with the notion of adversity. More recently, the Rockefeller Foundation set up the 100 Resilient Cities network in 2013 to inform and share best practices globally, helping cities to meet the physical, social and economic challenges of resilience and supporting the adoption and incorporation of resilience to shocks and stresses.
Urban resilience is ‘the capacity of individuals, communities, institutions, businesses and systems within a city to survive, adapt, and grow no matter what kind of chronic stresses and acute shocks they experience’, according to the network. The concept is dynamic and ever-changing. Cities and their hinterlands for instance are highly interdependent, and delineating their boundaries is problematic because systems such as water supply extend beyond city limits.
Why resilience matters
In 2015, the global population was 7.3bn, and the UN Department of Social and Economic Affairs predicts the total will be 9.7bn by 2050.
This growth is driven by more people surviving to reproductive age, changes in fertility rates, and increasing urbanisation and migration. Such trends have major implications in this, largest, wave of urban growth in history. More than half the world’s population now live in towns and cities, and two-thirds of them will be urbanised by 2050. Though urbanisation may improve wellbeing, resource efficiency and economic growth, cities also concentrate poverty and inequality.
Some assert that smart planning and governance will ensure that infrastructure can support growing populations. If so, as predominant land uses change we need to consider optimum levels of sustainable development, which will include different types and degrees of sustainable and resilient development, adaptation and adaptive re-use in buildings.
Cities tend to face 2 kinds of challenge: acute shocks and chronic stresses. Floods, bushfires and cyclones are examples of the former, while the latter, which can weaken the fabric of a city on a cyclical basis, include high unemployment and inefficient public transport. In addressing both shocks and stresses, cities can become more responsive to adverse events and better able to perform basic functions at all times for all citizens.
Table 1 shows the social, environmental and economic challenges faced in London and Melbourne, some of which are chronic and others acute. These impacts can be mitigated, in new and existing buildings alike, but different solutions suit different cities and different locations.
|London, UK||Melbourne, Australia|
|1||Coastal or tidal flooding||Ageing infrastructure|
|2||Crime and violence||Coastal or tidal flooding|
|3||Disease outbreak||Declining population or people leaving|
|4||Infrastructure failure||Disease outbreak|
|5||Lack of affordable housing||Drought|
|6||Poor air quality||Lack of affordable housing|
|7||Rainfall flooding||Rainfall flooding|
|8||Terrorist attack||Sea level rise or coastal erosion|
Table 1: Resilience challenges in London and Melbourne. Source: 100 Resilient Cities, 2017
Resilience scales illustrate how measures taken at building level can have a global impact (see Figure 1). Beyond this level, there is suburb or precinct level, then city scale, at which local policy is made and executed and governance is applied. After this is the metropolitan scale, then the national, where wider policy and governance decisions are made and executed. Following this is regional scale – for example, Europe – where some collective decision-making may be exercised. The final scale is global.
Figure 1: Resilience scales
Types of resilience
Resilience theory explains complex socio-ecological systems and their sustainable management. It offers a framework for dealing with uncertainties, as well as positive actions to make us less vulnerable to climate change, natural disasters and those caused by humans. To accommodate growth and expansion, cities and buildings need to be resilient.
Resilience has 5 attributes:
- whether a system exhibits equilibrium or non-equilibrium;
- positive and negative perceptions of resilience;
- mechanisms of systemic change;
- adaptation or general adaptability; and
- timescales of action.
Equilibrium can have a single or multiple states, or comprise dynamic non-equilibrium. Single-state equilibrium – the ability to return to a previous state after a disturbance – is a concept that prevails in disaster management, and can for example be seen in the reinstatement of buildings after flooding. Multiple-state equilibrium instead concedes that there can be numerous states of equilibrium.
Where systems exist in dynamic non-equilibrium, there is no constant state but rather continuous flux and change. This rejects the notion of resilience as bouncing back, and means systems are safe to fail rather than fail-safe, acknowledging that, after a disturbance, cities and buildings may not return to their former state.
Indeed, a return to normal may not be desirable because ‘normality’ was vulnerable in the first place. If this is the case, retrofit measures might give a building greater protection or allow it to resume operation faster after a flood. Some professionals and experts advocate such a coordinated, proactive approach to risk mitigation and adaptation in urban planning and buildings.
Positive and negative perceptions
Definitions of resilience are typically positive, with systems being designed to maintain basic functions, prosper and improve. However, some people question the desirability of maintaining existing states when these can include, for instance, areas with poor-quality housing. They ask who benefits from resilience, and to what we are applying the concept. Power inequalities then determine whose agenda prevails.
Mechanisms of change
Three mechanisms for systemic change are as follows.
- Persistence: efforts to return the built environment and its systems to a previous state or maintain it in its current one can be characterised as persistence. Examples include building reinstatement after a cyclone or, more straightforwardly, building refurbishment.
- Transition: this implies some adaptation to a new state, or incremental change. Conversion from a former use – say, from offices to residential accommodation – is an example.
- Transformative: the most extensive change is that in which areas are completely transformed, such as London Docklands’ redevelopment into the Canary Wharf business district.
Too much emphasis on resilience to specific risks can undermine flexibility and the ability to adapt to the unexpected. For some, adaptability is synonymous with adaptive capacity, where maintaining general resilience to unforeseen threats as well as specified resilience to known risks is important.
One example is the known risks of rainfall flooding when measures can be taken in building design, construction and adaptation to reduce the chance of damage and ensure faster recovery. Cities that are predicted to experience more intense rainfall as the climate changes can adapt designs now to make buildings more resilient.
Adopting flexible building design and construction might accommodate a greater variety of alternative uses over time, thereby enabling adaptive capacity. The Tower of London has a high adaptive capacity; in 900-plus years, it has functioned as home, prison, barracks, armoury, museum and tourist attraction. Warehouses also have good adaptive capacity, with many alternative uses.
Some experts, building owners and occupiers perceive rapid recovery as essential. However, it depends on whether rapid onset events, such as storms and floods, or more long-term gradual states, such as a changing climate, are the focus of concern. Reinstating energy supply after a storm could take a few hours, whereas reinstatement of flood-damaged buildings might take months.
There is also a question of whether reinstatement should be a return to a prior state, or to an improved state with greater resilience to the same kind of threat. Urban transformation requires long-term goals at city or state level, but it is at the building level where interventions and adaptations occur and where professional practitioners are catalysts of change.
Resilience is a growing consideration for many clients who want to protect people and investments. Building surveyors have a key role to play in responding to this. We need to teach resilience in universities and offer CPD to property professionals, while in advising clients we need to take a long-term view and a broad perspective by, for example, setting specifications that will enable buildings to withstand future weather events.
As building surveying professionals, we need the knowledge and skills to deal with resilience as well as risk assessment, and an understanding of probability in order to advise clients. We have to be proactive. With our comprehensive understanding of technical matters, pathology, value and legal and planning issues as they relate to buildings, surveyors are in a strong position to guide and advise on resilience. In the next article, I will explain what we can do.
Sara Wilkinson is Associate Professor, School of the Built Environment at the University of Technology, Sydney
- Some content in the article is taken from the book Building Urban Resilience through Change of Use, edited by Sara Wilkinson and Hilde Remøy, published by Wiley
- Related competencies include Construction technology and environmental services, Design and specification
- This feature was taken from RICS Building Surveying Journal (May/June 2018)
- Related categories: Building climate resilience; Flood remediation; Overview: sustainability in infrastructure; Sustainability for surveyors