Circular Cities

3 models for a sustainable city: the Circular Economy applied to the urban context

A story of two cities. The first is the city as we have known it so far. The air made unbearable by pollution. It is very difficult to dispose of waste properly. Resources are widely wasted or underused. The other is a sustainable and circular city. Here the waste does not exist, the resources are used to the best according to the rules of the sharing economy and the energy required is completely produced from renewable sources.

In the middle, there are the real cities, which are more or less similar to one or the other model. Cities are the first context in which it is essential to apply the terms of the Circular Economy. Because they represent an area in which it is perhaps easier to agree on its founding principles. Also because, above all, they are the place par excellence where humans live and will live.

Why the cities?

According to a World Bank report, 54% of the global population lives in urban areas and in cities, 85% of world GDP is produced (data: 2017). 75% of the natural resources are consumed here, 50% of the waste produced and greenhouse gas emissions equal to 60-80% of the total, according to different estimates.

It is therefore clear that we need to start from the cities if we want to influence the way in which human beings live together and exploit resources. Also because the trend is destined to increase, by 2050 75% of the population will be living in cities.

This means that even more funds will be invested in cities: infrastructures will be at the center of the growth strategies for the cities. Increasingly, natural resources, capitals, talents, and data will be concentrated in urban contexts. Moreover, given their relative geographic limitations, cities can better be governed and directed towards the principles of the Circular Economy.

The risk is that the global middle class, growing everywhere except perhaps in the “developed” economies and concentrated in the cities, ends up requiring an even greater percentage of resources to feed its “well-being”. This would inevitably lead to higher waste generation (which also means a decrease in material productivity) and a huge negative impact on the environment.

Some real examples will help us to understand what is at stake.

Why is the sustainable city the only way?

The city is the place for excellence, where humanity resides and will reside. This can be a source of opportunity, but also of problems.

We remember some of them.

The under-utilization of materials. Among the founding principles of the Circular Economy is the use of materials in a continuous cycle, without turning them into waste. Expanding the concept, we can say that the materials are always used to the maximum of their potential and without waste. This does not always happen, even more in the cities. Considering the cars, according to some reports, in Europe cars are parked on average 92% of the time. A huge waste of resources. In the same way the offices: the structures are used for just 35-50% of the time.

Waste of food (and not only).

31% of food in the world is wasted at the different levels of the chain: from production to distribution to consumption. This represents not only a social problem, but also an enormous waste of resources: the production of fruit, vegetables and meat is one of the activities with a relevant environmental impact.

The picture becomes even less positive when we consider that such waste must be disposed of with further costs in terms of economic resources. In developing countries 50% of the city’s budget goes to waste collection and management.


As mentioned, urban areas contribute to most of the emission of greenhouse gases into the atmosphere. Another fact that should makes us reflect: about 80% of urban areas have a level of air pollution that exceeds the limits established by the WHO.

The impact of climate change and global warming should be particularly felt by cities, given that 90% of urban areas are located along the coasts.

A vision for the sustainable and circular city

The urban contexts must, therefore, assume circularity as a basic model. To achieve this, they must exploit materials, technologies and flows that optimize and connect infrastructures and those who live in them, with their human and social capital.

To the most detrimental aspects of living in urban contexts, the circular city can, on the contrary, put in place a series of principles and actions to completely overturn the paradigm.

Three principles

We start from three principles on which the circularity is based according to the Ellen MacArthur Foundation.

To design. Circular production and consumption processes involve the elimination of all the negative externalities linked to the creation of value: toxic substances released into the environment, greenhouse gases, water and soil pollution, traffic congestion and so on. To achieve this, a systemic project is needed in which all the actors are involved at the highest level in a joint effort.

Eliminate the concept of waste. The idea of ​​an ideal sustainable city is not so much (or at least not only) that of recycling the materials that are discarded and end up in the trash can. On the contrary, the idea is to minimize the use of non-recycled materials. This is the idea behind the concept of circularity: the materials are not discarded but reused continuously, in a continuous cycle. At the same time, synthetic materials must be gradually replaced by organic compounds of a biological nature.

Regenerate. Natural capital is a value to be preserved and included in the circular process of the economy. An example is the regeneration of the soil, which can be obtained by avoiding polluting wastewater to go directly in the soil, but instead using compost, deriving from the organic materials mentioned above.

What can not be missing in a sustainable and circular city

On these general principles, then practices are founded, which can help to realize the dream of a circular city.

Buildings. Offices and houses are built in a modular and flexible way so that they are not used by a single owner but shared as much as possible. The construction materials must be reused and recyclable, reducing the use of virgin materials. Buildings must not consume as much energy and food as they produce, with systems for the production of energy from renewable sources and installations such as urban vertical farms.

Energy. Overall, the city must use energy that is renewable, distributed and efficient, cutting production costs and protecting the environment.

Transportation. As for buildings, even in transport it is necessary to overcome the concept of private property. The transport system must be accessible to all (and therefore economically advantageous) and holistic: to the “traditional” solutions such as trains and buses, electric on-demand cars, bike sharing and other solutions for the so-called “last-mile” must be added. Vehicles will also have to be rethought to last longer and to consume materials and fuel to a minimum.

Urban bioeconom. Food waste is another scourge, social and environmental, of urban areas. Here too it is possible to use a circular approach. The polluted waters do not end up in sewers (and therefore in watercourses), but are purified and sent to the land or in hydroponic crops. The organic fraction of waste – to be reduced to the minimum possible – becomes instead the fertilizer of those crops or material to feed fish farms, for example. What remains can lead to the production of clean energy (through biofuels).

Production systems in a loop. The production of goods and services can become widespread. The waste of a given activity can become, for example, the raw material of another. The tools can be shared and no longer be an exclusive property. Then, the faulty objects can still create value and work if they are repaired or reused.

Digital revolution. The Circular City can only be a Smart City. Mobility, for example, to be really efficient, requires the rapid processing of a large amount of data. The same can be said of the energy distribution systems, or of the food production. Digital technologies can make the production cycle much more transparent, for example by tracing the ‘journey’ of materials from birth to reuse.

3 cities that are doing it

Examples of Circular Cities are already underway, considering pilots on Smart Cities, Sustainable Mobility, and Urban Farming. It is still missing an example of a completely circular urban context, at least if we consider big cities where this kind of target is quite demanding.

However, there are examples of the progress made in this direction. Let’s find out.

San Francisco

In 2009, the city on the bay took a fundamental decision: it was the first in the United States to make the separation of organic waste from the rest waste for all citizens and businesses. The 2020 target is to reach “Zero Waste” and today the recycling percentage exceeds 80%, among the highest in the world.

The Californian city is also at the forefront of the so-called upcycling. What is it? It is a recycling process of a specific material for the production of a good of greater value than the original one. One example is ReGrained, a company that takes waste from beer brewing processes and creates energy bars.

The next step for San Francisco has to be to reduce the quantity of virgin materials used at the beginning of the production / consumption cycle: the greenest product is the one that is not produced.


The Singapore challenge is particularly interesting because the city is in the third most densely populated country in the world. The efforts of local administrations have focused mainly on the protection of biodiversity.

To build new buildings in the city, companies must, for example, restore all the vegetation they have eliminated elsewhere. Many skyscrapers, then, which give a home to 80% of the inhabitants, are covered with gardens on the roofs. For this reason, Singapore is covered for 40% of vegetation.

The city has created an app that helps citizens to identify specimens of the 392 species of birds that take refuge on the island. Singapore has also launched, thanks to the collaboration with the managers of the local National Parks, the CBI, the City Biodiversity Index: an index that “measures” the biodiversity of the city through a series of parameters. The tool is also useful for other urban areas to evaluate its efforts in this direction.


What is perhaps difficult for many to understand is the fact that Circular Cities are not just a requirement for the environment, but a way to create better conditions for everyone.

In Seoul with the “Sharing City” initiative, the rulers are trying to prove this. The goal is to share everything that is not used. Precisely everything: some abandoned buildings have been refurbished with the contribution of many; those who had a suit lent it to those who could not afford it to present themselves for a job interview; the same was done for children who go to school.

Among the most interesting projects, the redevelopment of Cheonggyecheon. A heavily polluted area has been transformed into a public space for recreational activities. The project has brought not only an undeniable environmental and social value but also an economic boost, with the creation of many jobs.

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