Circular Cities

Our economy can be characterized by the “take-make-waste principle”, which results in cheap mass-products that are thrown away at the end of their life-cycle. This article examines the transition to a circular economy and its contribution to a humane society.

The picture above is the Waste house at the university campus of Brighton, constructed from local waste.  In our society reuse of waste still is limited. Repair of household appliances seems to be not done: Last year, three devices in my home broke. No shops could fix them, although surfing the Internet revealed the existence of replacement parts.  I’d better buy a new one, they advised. I replaced the freezing compartment handle of the refrigerator myself. It was not difficult at all, but the price of the tiny replacement part was 25% of the price of a new refrigerator.

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Circular cities is part 7 in a series of essays on how cities can become more humane. That means finding a balance between sustainability, social justice and quality of life. This requires far-reaching choices. Once these choices have been made, it goes without saying that we use smart technologies to realize them. The essays that have already been published can be found here.

The flow of materials

A closer look at the flowchart of materials below is enlightening. Look here for a larger copy. 

The graph reveals that the volume of resources extracted in 2017 was 84,4 Gt (billions of ton), supplemented by 8.4 Gt reused ones: Minerals (37.9 Gt,) ores (9.6 Gt, fossil fuels (16,6 Gt) and biomass (28,7 Gt).

Of this material input (92.8 Gt), 36.0 Gt became part of the long-term stock of buildings, roads, cars and other capital goods. The largest part (56.8 Gt) was used for the production of goods with a lifetime that does not extend beyond 2017.

In 2017 14.5 Gt was removed from the stock and went into waste and as mentioned 36.0 Gt was added, which resulted in 890 Gt of materials at the end of 2017. 51,9 Gt has been dispersed in the environment as emissions and 19,4 Gt is waste. The majority of which (13 Gt) comes from products with a short lifespan.

Of the total waste of 19,4 Gt, 8.4 Gt is reused, for example by water treatment, the production of biogas, through recycling (only 1,4 Gt) and by composting. The majority of recycled material is of low quality. The remainder, 9,2 Gt is ‘lost’ and is scattered in the environment.  For instance, through microfibres that are added to the ocean and might return in the food chain.

Almost half of all materials going into the economy – 42.4 Gt in 2017 – are used in the construction and maintenance of houses, offices, roads and infrastructure, the majority of which becomes part of the stock. Given their average life-span time of 50 – 100 years, it can be expected that the yearly input of waste from the stock will multiply the coming decades. Therefore, recycling building materials at the highest possible level must have priority.

Towards a circular economy

The problem of the ‘take-make-waste’-principle is not waste in the first place. The linear economy on which this principle is based is a major cause of greenhouse gas emissions and, moreover, leads to the depletion of raw materials by rich and emerging countries or better, their rich minorities. The extraction of resources by contemporary and previous generations will stagnate the developing of the world’s population in the future. Replacement by the circular principle can correct this lack of justice.

A circular economy is regenerative by design and aims to keep products and materials in permanent use, without the need to exploit additional resources.

It is based on four principles:

  • Decoupling the provision of new products and services from the availability of finite resources. 
  • Design out waste and pollution and other negative externalities of economic activity that harm human health and natural systems. This includes toxic substances, greenhouse gas emissions, air, land and water pollution, and traffic congestion.
  • Maintaining the highest value of components and materials by designing them for reuse, rework and recycling.
  • Maintaining natural capital through the circulation of nutrients and creating the conditions for regeneration of, for example, soil.

From 2012 until now, the Ellen MacArthur Foundation  has contributed significantly to the acquisition and distribution of knowledge about the circular economy. The section below is inspired by the Foundation’s work. The video is an introduction in the concept of circularity.

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The circular principle can be applied at different scales: On large and small businesses, on organizations, on individuals, globally and locally.  This essay focuses primarily on the urban level. The diagram below shows the flow of materials, nutrients, components and products, as discussed before.

Circular material systems

The two cycles represent fundamentally distinct flows of material: biological (left) and technical (right).

Biological materials can easily return to nature once they have completed one or more cycles of use (‘cascades’).

Technical materials such as metals, plastics and chemicals cannot return to nature without processing. Instead, we distinguish four ways to stretch their lifespan and preserve their value, so that no new raw materials have to be extracted.

  • Repairing and sharing;
  • Reuse by other users without major changes;
  • Renovate and overhaul, dismantle and assemble into a new product, possibly with the addition of new functionalities;
  • Recycling: tracing back the product to its original material, preferably at the highest possible level (for example, plastic waste becomes ‘virgin’ plastic). In this case the original product can be re-manufactured.

Decoupling the production of goods and the use of natural resources is positive for nature, the economy, business and society in general.

Benefits for nature

The benefits for nature are designing out waste, pollution and greenhouse gasses, limit or stop the extraction of raw material, and regenerating soils.

Economic and business benefits

Economic benefits include lowering the price of the material component of products and increasing the quantity and quality of labour.

Business will benefit by focusing on high quality products and on replacement components. There are ample opportunities for new business services.

New business models

The CEO Guide to the Circular Economy describes new business models to cope with and benefit from a circular economy. Three recurring elements of these model are:

  • Extending the lifecycle of products through the use of well-designed and high-quality components;
  • Repairing, upgrading, and delivering products as a service
  • Sharing by making products available for more people.

Instead of buying a new washing machine every 5-6 year, you rent a high-quality machine. If it breaks down still and cannot be repaired at home (for free) the same day, a replacement machine will be delivered (for free) and your previous machine will be repaired in the workshop pending placement elsewhere.

This model radically changes business operations. The number of washing machines produced within a certain period of time decreases by more than half, including the required raw materials. Shops become showrooms, where you select a device that is delivered immediately from the shop owner’s workplace.

You never have to worry about a broken machine, retail employment is shifting from sellers to repairers, and making washing machines shifts from mass production to craft.

Benefits for society

In the long term, anybody will embrace this new economy because of the (shared) use of high-quality products. Food will become more expensive, but the positive effect on people’s health will be significant.

Whether or not the principle of circularity will be implemented depends on the willingness to change of many, especially the most influential people and those with vested interests in the ‘take-make-waste‘-economy.

Before discussing the role of cities and city governments in particular, I will elaborate on the circular principle and illustrate it in two cases: The production of plastics and the construction sector.


Plastics are versatile materials. However, their production contributes to greenhouse gas emissions and plastic waste threats our health. The way in which plastics have developed and are distributed illustrates that a circular economy stands or falls with product design. So far, the design of plastics reflects the ‘take-make-waste’principle: Every year more than 300 million tons of plastic are produced worldwide, half of which are for single use. Only 10% or all plastics are made from recycled material.

Plastic waste that ends up in nature degrades into micro plastics – plastic soup – and retains its chemical composition and toxic nature. Micro plastics eventually end up in the food cycle. More than 100 million tons of plastic already float in the oceans.

In the meantime, alternatives are being searched for, albeit far too late. Unilever leads the way. The company currently produces 700,000 tons of plastic packaging. This will be reduced by 100,000 tons in 2025. Moreover, the company wants that all its plastic packaging becomes reusable, recyclable or compostable and that at least 25% recycled plastic is used in the production of new plastic.

Below is a brief overview of the different options.


Preventing plastics from entering nature requires an extensive and cost-effective system for collecting and separating waste and technology for high-quality recycling of the collected plastic waste.

The separation of waste

In case of a single-stream collection system, people throw plastic, glass, metals and paper into one collection bin. As a consequence, these items have to be separated. The video below shows the operation of a large-scale separation line.

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As can be seen, quite a lot or human assistance is needed. New machines limit this unattractive work thanks to artificial intelligence. They are able to separate 20 different types of plastics.

Chemical recycling

One of the biggest hurdles in recycling plastics is its pollution, for instance as a result of added dyes. The Dutch company Ioniqa can chemically reduce PET waste to ‘virgin’ PET. Large plastic users like Coca-Cola intent to co-operate with Ioniqa. The video below shows how chemical recycling works.

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Use of sustainable raw materials (biobased plastics)

The advantage of using sustainable raw materials (biomass) in the production of plastic is the reduction of CO2 emissions. However, biomass is becoming increasingly scarce and its production can compete with food crops and forestry. Moreover, most bio-based plastics are not biodegradable. If they end up in litter, the effects are as harmful as those of other plastics. For these and reasons mentioned below, there are quite some disadvantages associated with biobased plastics.

Biologically degradable plastics

Ideally, these biologically degradable plastics are biobased materials, which are safely broken down in nature in short time. PHA for example. Unfortunately, years of research have not yet led to its large-scale production.

Some other types of plastics such as PLA (biobased) and PBAT (not bio-based) are compostable, but only in an industrial environment. These types of plastics may be added to the organic waste. However, most consumers cannot distinguish between biodegradable, biobased and other types of plastics. As a result, many plastics unintendedly end up in the plastic soup.


If plastic had been designed for a circular economy from the start, the emphasis would undoubtedly have been on reuse. This also applies to industrial applications such as PVC. Thanks to a substantial deposit, the majority of all plastics could be reused than.

Back to reusable packaging?

Together with Coca-Cola, Proctor & Gamble, Nestlé, Unilever has joined Loop, a platform that develops refillable packaging. Supermarkets that deliver products at home can easily include them in their range. The video below shows how the system works.

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Ban on some types of plastic

The collection of plastics still is still seriously inadequate and a large proportion of plastics ends up in nature as visual litter and return to our food chain as toxic plastic soup. This applies in particular to plastic bags, cups, trays for snacks and soft drinks bottles without a deposit. A ban seems to be the only way-out.


The impact of circular principles in the construction sector is huge, because buildings are responsible for more than 50% of the total use of materials on earth, including valuable types such as steel, copper, aluminium and zinc.  Moreover, they produce about 40% of all greenhouse gases.

By circular construction we mean designing, building and demolishing a building in such a way that, in addition to the high-quality reuse of materials, justice is done to sustainability ambitions in the field of energy, water, and biodiversity and ecosystems.

Structural waste in the build environment. Source: The circular economy: Moving from theory to practice, McKinsey & Company 2015

In case of demolishment, nowadays many components are reused, but at a very low level, for instance concrete and stones as the foundation of new roads. Apart from the question how many new roads are still needed, this type of recycling destroys the intrinsic quality of materials and does not diminish the recovery of new materials. At least, separation of glass, steel, wood and other materials can be made mandatory. In addition, valuable materials can by ‘saved’ by operating in a targeted manner, even though these buildings are anything but circular. This is called ‘urban mining’. The biggest problem is that recycled materials are often more expensive than new ones.
Anyway, a first step is more efficient use of existing buildings. Evidently, progress can be made by planning, designing, developing and building circular buildings. A number of options are mentioned below. 

Urban planning

Challenges for planning are the use of inner-city vacant land and issuing mandatory requirements regarding the construction of new buildings, for instance the use of less cement, glass and steel, the mandatory application of a certain percentage of reused materials, and becoming energy positive or at least energy-neutral. Switching to sustainable timber is an option for 90% of homes and 70% of offices being built.

Mandatory reuse of existing components

Reuse of existing materials means than glass is reused as glass and concrete pillars as pillars. The same applies to doors, frames, carpets, wall-cladding materials and so on.

The materials passport, which contains an overview of all materials and components that are used to construct of a house or building, is a useful tool as well. The obligation to reuse a large percentage of existing components has far-reaching consequences for the design and construction of new houses. To start with, after demolishment all materials must be selected, cleaned, registered and stored in new-to-develop warehouses.

The Circl pavilion of the ABN-AMRO bank

The Circl pavilion of the Dutch ABN-AMRO bank is an example of a new building that uses as many existing components as possible. For instance, 1200 m2 of wooded floors, partition walls of a demolished building and 16.000 garments of employees for isolation purposes. All components of the building are designed to be reused.

Industrial production and 3D printing

Construction of components in factories, deploying industrial processes, will reduce costs by 30 percent and the delivery time by at least 50 percent.

Printed houses and buildings

In 2014, the Chinese company WinSun printed and assembled ten houses, each 195 square meters, in 24 hours, for an amount of €5,000 per house. The company used 30 – 60 percent less material than in traditional construction. The “ink” for their 3D printers is a mixture of dry cement and construction waste. WinSun plans to open 100 recycling plants in China to convert waste into cost-efficient ink. The video below demonstrates the printing activities of WinSun.

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Sharing space

The size of apartments will decrease, partly due to costs, but also because of the presence of shared guest rooms, lounge areas and terraces for working and socializing, spaces for washing and drying laundry.

The need for office space will decrease rapidly due to sharing space and working in an external environment. So IBM has only one desk available for 12 employees. Given the presence of 300,000 employees, this has led to savings on real estate of around € 1 billion in the past 10 years.

Modularity and durability

A key barrier for better use of floor space is the lack of flexibility in the design of buildings and room configurations. A modular design, which provides for easy replacement of partitions and placement of complete functional units (kitchens and bathrooms) facilitates adjustments as the use of a building changes.

Flexible room solutions

DIRTT builds interior components that are modular and standardized and offer maximum interchangeability in both existing and new buildings. The video below gives an impression of the production and application of these flexible and inexpensive solutions.

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Forget new construction at all

As families become smaller and offices need less space, existing space becomes more underused. Well-thought adjustments to the lay-out of existing houses and buildings can improve their efficiency without reducing their amenity.

The impact of circular principles on cities

Circular construction lowers housing costs and protects land from degradation, fragmentation and non-sustainable use; reduces the negative impact on the environment and improves the quality of life in cities.

At the same time, current income from cities – 85% of global GDP – is closely linked to global flows of oil and gas, raw materials, components and end products and – as a result – major interests of leading companies and influential states in the ‘take-make-waste’ economy.

The development of a circular economy is a struggle for power and influence, which can only be won in favour of circularity through a joint effort. Cities are pre-eminently the platform for this struggle, because here all stakeholders meet, they can exchange ideas and possibly reach an agreement based on shared interests.

The role of the city government is decisive.

Firstly, by bringing parties together, developing inspiring goals, removing barriers arising from existing regulations, facilitating sharing, stimulating innovative research, supporting start-ups that contribute to circular solutions and providing financial incentives, for example, by differentiating tax rates.

Secondly, by making circular plans in areas where the city government is primarily responsible. Local authorities have a large and direct influence through legislation and investments related to urban planning, issuing building permits, mobility systems, urban infrastructure, district heating, energy production and distribution, waste collection, municipal taxes and the local labour market.

The city can even make a difference, which can be illustrated in the Amsterdam metropolitan area.

Circular Amsterdam

The municipality of Amsterdam has committed itself to the circular economy as an important pillar of its sustainability policy. The city wants to be a forerunner and has a good starting position because many citizens, businesses, start-ups, and (knowledge) institutions are convinced by the necessity of a circular economy.

The municipality applies the following principles:

  • All materials are part of an infinite physical or biological cycle.
  • All energy comes from renewable sources.
  • Modular and flexible design of production chains to increase the adaptability of systems.
  • New activities that enable the shift from possession of goods to use of services.
  • Logistical systems that switch to more region-oriented services.
  • Human activities that contribute to the regeneration of “natural capital”.

Together with external parties, such as TNO and Circle, the city has evaluated existing value chains with respect to ecological impact, economic importance, value retention and transition potential. This resulted in a selection of two fields (‘chains’) in which the greatest circular impact can be achieved, namely the construction chain and the organic residual chain.

Construction chain

By organizing the construction chain in a circular fashion and at the same time realizing 70.000 new homes by 2040, a 3% productivity gain is feasible representing a worth of € 85 million per year. This is the result of reusing material and efficiency improvements. The table below is mentioning the main activities to be developed in the next years.

Source: Municipality of Amsterdam

Organic residual streams chain

High-value processing of organic residual flows over a period of five to seven years, will result in an added value of 150 million euro per year. This is the result of source separation of organic waste in all households and in the food processing industry. The organic residual flow is used for the production of proteins for animal feed, biogas and building blocks for the production of bio-plastics. The table below is mentioning the main prospective activities to be developed in the next years.

Source: Municipality of Amsterdam

In certain respects, countries with a lower income are more “circular” than richer counterparts. Many residents cannot afford to throw away valuable material. In the informal sector, a great deal of economic activity revolves around sorting and reusing waste, including imported waste from rich countries. About 0.5% of the urban population in developing countries – 1.5 million in India alone – tries to make a living by collecting items from landfills, with all the health risks this entails. An estimated 270,000 people die each year from the incineration of waste. It is estimated that in 2025 landfills will cause 8 – 10% of global greenhouse gas emissions.

Developing countries must follow their own path, which is different from ours. Here you can think of:

  • Prioritizing the management of (organic) waste, separating and processing streams.
  • Collecting usable components of buildings and houses to be demolished and making them available to residents of slums, together with improvements in the provision of drinking water and sanitation.
  • Increasing taxes on raw materials and creating investment funds to support the recycling of industrial waste.
  • Setting up places where residents can deposit household waste both in and outside cities and prohibiting the incineration of waste in unauthorized places.
  • Focus on high-quality plastic products and, as far as possible, prevent the mistakes made by developed countries.

Circularity and the humane city

There is no doubt that in the long run everyone benefits from a circular economy. However, in the short term it can weaken the purchasing power of the poor. Poor people around the world have already created an informal circular economy by buying or exchanging worn-out goods such as cars, refrigerators, furniture, and clothing. Goods that are available at flea markets, thrift stores or through family and friends. As soon as these goods become part of a regular circular process, their availability will decrease and their prices rise. Not to mention a ban on selling these goods for environmental or safety reasons.

This problem is not inherent in the circular economy, but arises from the growing gap between the rich and poor part of humanity. Consequently, policies aimed at the development of a circular society must also create the conditions for a more just and egalitarian society.

Actions to align the principle of circular economy and the development of humane cities

1. A worldwide increase in raw material prices is the best contribution to a circular economy, in the short term especially for developing countries and in the long term for everyone because higher raw material prices will encourage recycling.

2. At present, components of demolished buildings are not suitable for large-scale reuse. In developing countries, they can be made available to residents of slums to improve their primitive homes.

3. Architects must agree as soon as possible on the use of a relatively limited number of standardized, industrially produced components for new buildings. In the coming decades, these components will be supplemented and increasingly replaced by components from demolished buildings. Storage of these components is best organized as a municipal level to create substantial supplies and prevent long-distance transportation.

4. Developed countries must stop exporting their waste to developing countries and emerging countries. The export of waste is a reprehensible way to reduce their ecological footprint in their own country. Stopping exports forces them to give priority to facilities for reuse and recycling.

5. Preventing litter through additional taxes for companies that produce single-use packaging is not effective. They will just raise his prices. Instead, this type of packaging should be prohibited.

6. The development of a sharing economy goes beyond the replacement of products by services. It also includes collective ownership of utensils, books, toys, and many other goods.

7. Plastic objects must radiate quality and durability instead of being experienced as something to throw away. Substantial deposit for all plastic bottles and boxes for packaging meat, cheese and salads must be considered reasonable.

8. Plastic items that are not reused must be collected in one waste stream, aimed at producing high-quality types of new plastic. Given a successful combination of reuse, collection and high-quality recycling, the production of biodegradable plastics is less urgent.

9. Cleaning up plastic waste in the oceans and avoiding the use of microplastics in consumer products has high priority.

  • This article was brought to you by Professor Herman van den Bosch, Professor at Open University of The Netherlands.
  • The header photo shows the Brighton Waste House, a project of the Faculty of Arts and Humanities. Photo: University of Brighton (public domain).