What is a sustainable city?

By Matt Burdett, 15 May 2020.

In this article, we look at what is meant by a ‘sustainable’ city, with reference to systems theory, ecocities and resilient cities.

  • Plaza Cisneros, Medellin, Colombia. The creation of art installations in public spaces such as these 300 lighting poles aims to rejuvenate the city and reduce crime in public spaces. Such social development is part of sustainability. Source: By the author.

What is ‘urban sustainability’?

The general principle of sustainability is the same in all contexts: it is the idea that a given activity can be continued indefinitely. A good definition of urban sustainability is that “a sustainable city should meet the needs of the present without sacrificing the ability of future generations to meet their own needs” (Siemens, n.d.).

However, this doesn’t account for the desire to increase living standards beyond meeting ‘needs’, nor increasing the quality of life of inhabitants. In a city such as Medellin in Colombia (shown in the photograph at the top of this page) most of the basic needs of the population are met (heat, shelter, food, water and so on). However, after struggling with criminal activity for decades, the city is attempting to rejuvenate itself by reducing crime and increasing the safety of public spaces for everyone. In this way, sustainability can be seen as more than simply the meeting of needs, and other aspects of sustainability – such as social and economic improvement – are also included.

As a result, most definitions for a ‘sustainable city’ refer also to the issue of sustainable development. This has been a focus of improving lives for many of the world’s poorest people: cities have been a focus of sustainable thinking for decades in tandem with efforts to increase wealth. As more people live in cities, both in absolute terms and as a proportion of world population, sustainable cities have never been more important.

The importance of improving human lives alongside increasing the sustainability of cities is recognised in Goal 11 of the Sustainable Development Goals: “Make cities and human settlements inclusive, safe, resilient and sustainable” (UN, n.d.). The SDGs do not explicitly identify what makes a city sustainable, but the targets and indicators available at their webpage suggest:

  • Adequate housing, transport and economic development
  • Ensure planning is sustainable, i.e. future-oriented
  • Protect cultural and natural heritage, and increase public and green spaces
  • Reduce disasters and the impacts of climate change

The city as a system

A sustainable city is one that uses resources carefully to meet the needs of its population while improving their lives, and can do so in the future too. This means that the inputs and outputs need to be carefully managed. The diagram below shows one interpretation of the difference between an unsustainable and a sustainable city, using a systems approach.

  • Linear and circular – or unsustainable and sustainable – models of cities. Source: Rogers, 1997.

Systems approaches emphasise the inputs, processes, stores and outputs of a city. When the inputs and outputs are minimised and capable of being created and absorbed without harming the wider environment beyond the city, a city is sustainable.

Cities cannot be entirely self-sustained. It would be impossible for any city to meet all the needs of its population without using some land, air and water beyond the city limits. The systems approach emphasises that the processes in the city need to minimise the impact on the wider environment.

Sustainability, ecocities and resilient cities

An ecocity is a city that aims to be in balance with its environment – to require no more resources than it can provide, and to create no more waste than it can absorb. There is a massive overlap between the concept of the ‘sustainable city’ and the ‘ecocity’ and many sources use the terms interchangeably. To differentiate between the two, it can be helpful to think of an ecocity as focusing on the ecological aspects of sustainability in its journey to becoming a fully sustainable city, whereas some sustainable cities may look to other pillars of sustainability (such as economic and social development) as their routes towards becoming truly sustainable.

A resilient city is one that can withstand shock events, such as a major disaster, and slow-onset problems such as a rise in sea levels due to climate change. The emphasis on resilience is about coping during such events and recovering afterwards. It is vital for cities that want to be resilient to be sustainable too; the fewer inputs and outputs to the city, the greater the capacity of the city to increase these inputs and outputs in times of need. More detailed information about resilient cities is available on the ‘Resilient Cities’ page elsewhere on this site.


Huang, Wu, and Yan, 2015. Defining and measuring urban sustainability: a review of indicators. Landscape Ecol 30, 1175–1193 (2015). https://doi.org/10.1007/s10980-015-0208-2 Available at https://link.springer.com/article/10.1007/s10980-015-0208-2 Accessed 11 May 2020.

Rogers, R., 1997. Cities for a small Planet. Icon editions, Westview Press.

Siemens, n.d. What is urban sustainability? https://assets.new.siemens.com/siemens/assets/public.1560756617.90627521-4620-4b1d-9dc6-d94563b93a46.what-is-urban-sustainability-v1.pdf Accessed 11 May 2020.

UN [United Nations], n.d. Sustainable Development Goal 11. Sustainable Development Goals Knowledge Platform. https://sustainabledevelopment.un.org/sdg11 Accessed 11 May 2020.

What is a sustainable city? Learning activities


  1. Define ‘sustainable’ in general. [1]
  2. Define ‘urban sustainability’. [1]
  3. Briefly outline Goal 11 of the SDGs. [3]
  4. Distinguish between the linear and circular city systems. [4]
  5. Explain the difference between a sustainable city and an ecocity. [2]
  6. Explain why resilient cities must also be sustainable cities. [2]
  7. Suggest why sustainable cities are increasingly important. You may find the information about ‘Urban Growth Projections’ elsewhere on this site helpful. [6]

Other tasks

Is your nearest city a sustainable city? Explain your reasons.

© Matthew Burdett, 2020. All rights reserved.

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