Circular construction – an opportunity we can’t waste

Did you know that:

  • Cities consume more than 75% of all natural resources?
  • We have to build a city the size of Paris – every week – for the next 30 years to accommodate global population growth?

Key solutions are therefore to change the processes and materials used in the built environment. Based on examples provided in this report:

  • More than 50% of CO2e emissions from heavy industry can be cut through a circular economy
  • Circular economy initiatives could reduce 40% of CO2 emissions generated by production of cement, plastics, steel and aluminium for infrastructure
  • Refurbishment could achieve up to 59% reductions in carbon emissions

To scale up the impacts of greater circularity, we need to shift away from individual projects to a systems mindset. This report identifies 3 key trends. It presents case studies on circular activities and puts into focus the circular use of materials and digital tools, and identifies the steps taken to accomplish greater circularity.

Trend 1: Climate change and the need to change

When dredging turns waste into value

Dredging. The word conjures up the disposal of something worthless or unwanted, like a waste product. But in a circular economy, not only does it play a role – it can become valuable in its own right.

“Our water-passing tile is made from dredged sediments,” says Wies van Lieshout, co-founder of the Dutch start-up Waterweg. “It’s a circular, climate-adaptive product. The tiles are made from river sediment waste and provide a solution for flooding in cities. Dredging is the tool we use to make an impact.”

The summer of 2021 saw flooding across Europe, and together with climate change is not a problem that is likely to go away. Recycling alone no longer suffices for achieving an economy that is truly circular.

“During budgeting and financial planning, we really have to go beyond creating spaces for production and employment – it’s a complete mind shift,” says Kathleen Van de Werf, Business Development Manager at BUUR, a part of Sweco. “We have to think about the future of spaces and cities. It’s not only about closing loops.”

Although the world’s cities currently occupy less than 4% of Earth’s surface, they are home to 55% of the global population. They consume more than 75% of our natural resources, produce more than 50% of all global waste, and emit 60-80% of global greenhouse gases. These are all symptoms of a take–make–dispose linear economic model. And cities continue to grow: by 2050, two-thirds of us will live in cities.

This calls for a change.

“If it can’t be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted, then it should be restricted, redesigned or removed from production.”

So sang Pete Seeger, the U.S. folk singer and social activist, as early as 20 years ago. Today, the need for change is becoming increasingly evident.

A value-driven visualisation

A value-driven visualisation of the Ströms building in Gothenburg based on its carbon footprint from its whole life. Visualisation tools can be crucial to point out circularity aspects such as the reuse, recycle, and upcycle potential.

Trend 2: natural resources are being exhausted, the need for circular thinking is necessary

The European circular promise

In March 2020, the European Commission adopted the Circular Economy Action Plan as a part of the European Green Deal with the goal to achieve a carbon-neutral, sustainable, non-toxic and fully circular economy by 2050.

As a part of the plan, 70% of all construction waste must be recycled from 2020 onwards, accelerating the construction industry’s switch from a linear to a circular strategy.

Many European countries have presented an agenda of their own. In 2016, Finland became the first country in the world to prepare a strategic national roadmap for a circular economy by 2035. Denmark followed, launching its circular economy strategy in 2018 for full implementation by 2022. The U.K. is another example, with generally the same plan as the European Commission’s.

In 2021, an international alliance called the Global Alliance on Circular Economy and Resource Efficiency (GACERE) was formed to drive the global circular conversion. A growing number of cities have also prepared circular economy plans, roadmaps or declarations, several of which pre-date the 2020 Circular Economy Action Plan. Amsterdam, London, Glasgow, Copenhagen – these are just some of the cities recognising the need for cities with definitive plans to increase circularity within their own urban resource systems.

These plans re-think cities as circular resource systems, and identify action plans to turn this thinking into reality.

Illustration The circular socity

Illustration: The circular socity. Design by Sweco.

Trend 3: Regenerative thinking: opportunities for scalable, circular systems – cut out old materials and habits

More than half of the EU’s CO2 emissions from heavy industry could be cut by adopting a circular economy. In an ambitious scenario, a full 296 million tonnes out of 530 million tonnes could be cut by 2050, according to the Swedish consultancy firm Material Economics.

Such plans also translate into purely economic gains. The total cost of providing goods and services in key EU value chains, such as mobility, housing and food, could be slashed by as much as EUR 535 billion each year by shifting to a circular economy. Moreover, a circular economy in Europe has the potential to boost the EU’s GDP by an additional 0.5% by 2030 and create roughly 700,000 jobs.

Building a city the size of Paris – every week – for the next 30 years may sound like a preposterous plan and an outrageous waste of resources[1]. But this is exactly the scale that’s needed to build infrastructure capable of accommodating a global population expected to grow by 22% to 9.7 billion by 2050. It is estimated that 60% of the infrastructure needed to meet that growth does not exist today. It is not very hard to imagine the strain on the environment and the scarcity of materials that such a daunting challenge would lead to given the current trajectory of consumption.

Currently, about 39% of the world’s total greenhouse gas emissions are estimated to stem from the construction industry. At the same time, construction and demolition waste constitute nearly 30% of all waste in the EU.

Circular economy initiatives could reduce as much as 40% of CO2 emissions generated by manufacturing all the cement, plastics, steel and aluminium needed to meet our future infrastructure needs. The implementation of circular design principles during construction, as well as managing buildings as a dynamic resource systems during their lifetimes, could reduce energy and material consumption as well as enable a longer lifespan, more flexible use and better maintenance of buildings.

Global Carbon emissions related to material production

Total carbon emissions material production

In 2018 total carbon emissions were 55.3 GtCO2e. 21% of these emissions were related to material production, and 9% were caused by material production in the construction sector[2]

Sweco examples and case studies

The Green House-Utrecht, NL

In the Netherlands, ‘circular’ buildings like The Green House in Utrecht have attracted a lot of attention. Planned as a circular economy laboratory, this pavilion aims to serve as an inspiration for the circular economy, in both form and function. It is designed to operate for 15 years before needing to be relocated or reused.

Its residual value is high because the building’s dismantling and relocation after 15 years was already planned for in the design phase. The use of new materials has been reduced by using windows from the adjacent Knoopkazerne barracks, ventilation pipes meet Cradle2Cradle standards, the floor covering consists of reused plastic, and all furniture is second hand. Through social media and a series of meetings, local residents have been called on to contribute their ideas for the plans. The project has created between 30 and 40 new jobs and office spaces with flexible workstations. The operator is collaborating with the restaurant Colour Kitchen, a social organisation that helps people get into the job market.

Refurbishment, renovation and, where needed, repurposing, will extend the life of existing buildings and thus reduce the need to construct new buildings. Several measures are also in place to improve the use phase. Underused spaces, such as apartments and offices, can be shared.

Haus der Statistik- Berlin, Germany

The Haus der Statistik project in Berlin is another great example. The building, which used to house the Stasi Records Archive, was saved from demolition thanks to an art auction in 2015. The initiative Haus der Statistik was later formed as an alliance among various stakeholders like institutions, artist collectives, architects, foundations and clubs.

Økern, Oslo- Norway

In the Økern development in Oslo, plans are underway for the reuse of an 18-storey building from 1970. Calculations made with One Click LCA software show that if the building was demolished and a new one built, the materials would account for approximately 4,000 tonnes of carbon. By contrast, preservation and refurbishing that would retain most of the heavy structures would emit about 1,900 tonnes of carbon – a reduction in emissions of approximately 55%.

Økern Centre in Oslo, Norway.

This high-rise building from 1970 has been reused. Elements of the landscape that have been lost for decades will be recreated by the development of Økern Centre in Oslo, Norway. Illustration: A-LAB and Økern Sentrum.

The City of Helsinki, Finland

We find another example using the same approach in Finland. The City of Helsinki aims to achieve carbon neutrality by 2035. This target is ambitious and requires implementation of a wide range of actions. In a district of Helsinki, buildings that were mainly constructed during the 1960s and 1970s are now in need of heavy refurbishing. According to Sweco’s construction calculations, such refurbishment could achieve as much as a 59% reduction in carbon emissions. Maintaining the existing load-bearing structures in steel and concrete in particular had a huge impact on lowering the carbon footprint. Moreover, the construction cost analysis indicated that a renovation would be more affordable than a new build.

Circle House, Lisbjerg, Denmark

The world’s first circular social housing project will take shape in the Danish city of Lisbjerg. Sweco is part of this project, which is expected to be completed in the spring of 2023. The project aspires to make 90% of the building elements capable of being dismantled and reconstructed for use in future buildings, at no additional cost.

The world's first circular public housing

Sweco join winning team: To realize the world’s first circular public housing built according to circular principles. This means that the building can be taken apart again and the aim is that 90% of the materials being used for the buildings can be reused without losing significant value. Visualization: RUM.

Sweco vision: solutions to rethink the process: digitalise and materialise

Materialising

Urban Mining and Materials Passports

All things come to an end. So does the life cycle of a building. However, that end could become a new beginning. Rather than being reduced to rubble or sent to landfill, an end-of-life building should be seen as a source of new materials, a “material bank”. But information about such available materials is scarce. Old buildings are poorly documented with little or no information about the dimensions of components or the quality of the components/materials, and often also lack the required documentation.

To increase the traceability of the materials in a building, materials passports could be introduced. Such passports provide information on the type and value of materials in a structure, as well as on how easily they could be disassembled and recovered. The Dutch company Madaster has developed such a digital library of materials, where buildings are registered with the materials and products that were used for their construction.

“Twenty years ago, everything in the city was focused on the production of houses as quickly as possible. It’s still important, but nowadays, we’re taking more time to do the right thing”, says Alfons Oude Ophuis. He is the project manager for Beach Island, one of six new islands in Amsterdam reclaimed from the waters using sand carried by boats run on low-emission fuel.

Anyone wanting to build on Beach Island will need to provide a “materials passport” for their buildings, so whenever they are demolished, the city can reuse the parts.

Investing in the reuse of the existing property portfolio crucial. Hotel Blique by Nobis in Stockholm is a clear example of how an existing block from the 1930s was reused to reduce climate emissions.

Hotel Blique by Nobis

Hotel Blique by Nobis. Architects: Ewa Buhr-Berg and Karin Hurtig at Sweco, photographer: Jeanette Hägglund.

In the renovation, which was completed in 2019, the ‘new-price’ value of recycled material was estimated at SEK 86 million, and saved climate emissions corresponded to 3,600 tonnes of carbon dioxide which equals SEK 25,5 million[3]

“It’s important to assess a building’s recycling potential at an early stage using different competences, in combination with digital tools that can count on different scenarios. With smart 3D modelling, we can let a computer calculate the climate savings at an early stage, and thus control the project right from the start”, says Elise Grosse, head of sustainability in construction and real estate at Sweco.

Another example is the Epic office building in Malmö, where Skanska used PET bottles as sound absorbers, concrete from the Copenhagen Metro for the floor tiles, and old window frames for wooden panels. And with August Gate 13 in Oslo, the extension and conversion of an office property included a significant proportion of recycled materials and building parts. This is the largest project of its kind in Norway.

In a project at Stationsplein in the Dutch city of Leiden, two buildings were set to be demolished. In collaboration with the municipality of Leiden, Sweco took the decision to approach the building specifications and general requirements for demolishing in a circular way in order to achieve the area’s ambitious sustainability vision.

“During the process, much insight has been gained on what can and cannot be done within building specifications and general requirements for the gathering of circular materials. This knowledge will be included in upcoming contracts for locations to be demolished by both Sweco and the municipality of Leiden,” says Richard Koops, Business Director for Circular Economy at Sweco in the Netherlands.

Stationsplein

Stationsplein in the Dutch city of Leiden: Reuse of materials and value retention are aspects a Circular Harvest Specification

To make reusing building materials easier, both private and municipal actors in the city of Borlänge, Sweden, have joined forces in a unique project, the Dala Recycling Depot.

“Building materials that previously only went into heating account for about 30% of the amount of waste. The construction industry has not been engaged in recycling at all, but has lived by the motto ‘the more that can be torn down and thrown away the better’. It’s not okay anywhere,” says Ola Berglund, claims manager at insurance company Länsförsäkringar Dalarna and one of the initiators.

The short-term goal is to sell at least 2,500 tonnes of material by 2023, which means that the amount of newly produced building material will have decreased correspondingly. The long-term 2030 goal is for recycling to become the norm in all of Borlänge’s construction projects thanks to the reconstruction depot. Sales in 2030 will be 4,000 tonnes of material per year.

Rotor DC in Brussels, an employee-owned company, has a similar aim. They collaborate with contractors, non-profit organisations and other companies to become a central part of a regional ecosystem for large-scale reuse of building materials. Construction City, an alliance of construction businesses in Ulven, Oslo, is another example of the potential of reusing building materials. The alliance has mainly focused on concrete. The project has the potential to reuse or recycle 70-90% of concrete, equivalent to 3,400 tonnes, by reusing and reconfiguring elements. As a result, it aims to reduce overall carbon emissions by 952 tonnes.

The same principle of design and business models for continual cycles also applies to components of a building during its lifecycle. Lighting, heating HVAC systems and more need to be continually serviced. Product service models where you pay for light, heat, ventilation rather than the hardware incentivise installers to design all components to be click-in click out easy installation and able to be reconditioned for reinsertion back into service. Designers of builders can play their part in the continual regeneration of the buildings services by providing open designs where services can be accessed and removed, rather than bricked in. The building is a dynamic resource throughout its life, not just at the end of its lifecycle.

Digitalise

Digital transformation and new business models

Different kinds of information and communication technology (ICT) tools can support business models in all phases of the circular economy. For example, building information modelling facilitates information management for all stakeholders. During the use phase, smart monitoring devices can anticipate problems and predict the need for maintenance.  The Internet-of-things (IoT) will enable ageing calculations based on environmental conditions which are essential to help distinguish products that should be repaired from those that require recycling.

Oris, developed by the Swiss company LafargeHolcim in collaboration with IBM, illustrates how artificial intelligence (AI) can be introduced in the design of infrastructure. This digital platform utilises secondary materials from demolition sites and other sources for road construction, with the design optimised to match the available materials. The platform for road design optimisation can, according to the companies, reduce road project costs by up to one-third and carbon emissions by half, while tripling road durability and lifespans.

Building features such as lighting, heating and HVAC can be run as services rather than products that are bought and installed. Schiphol Airport in the Netherlands buys light on a ‘pay per lux’ basis, paying for the light it consumes rather than the lightbulbs. Because ownership of the assets remains with the producer or installer, they are incentivised to design them for replacement, reconditioning and reinsertion back into the system. Track-and-trace systems for assets can alert staff when an asset is approaching the end of its useful life and should be replaced before it fails, thereby avoiding disruption. Smart meters can monitor performance and similarly diagnose the need for repair or replacement. The user is incentivised to use the service efficiently.

Finally, platforms like Madaster, an online registry for materials and products, can facilitate disassembly, recovery and reuse of an asset at the end of its life cycle.

A new perspective: putting digitalising and materialisation in practice

Material in focus 1: Circular concrete

If the production of cement would be a country, it would be the third biggest emitter of CO2 surpassed only by China and the U.S., according to a report from the British think-tank Chatham House. Cement production accounts for a full 8% of global annual CO2 emissions.

New ‘green concrete’ has been developed to reduce carbon footprint. ECOPact, from the Swiss company LafargeHolcim, recycles materials from demolished buildings and generates 30% less carbon emissions than standard concrete. This product has been used to build social housing in France. Geopolymer cement is another example, which relies on minimally processed natural materials or industrial by-products to significantly reduce the carbon footprint of cement production while delivering high durability performance.

CarbonCure, a US-based company, has developed a technology that injects recycled carbon dioxide into concrete, after which it mineralises and becomes permanently embedded in the concrete.

Material in focus 2: Hempcrete and foldable building blocks

Jean Dethier, the Belgian architect and former adviser for architectural exhibitions at the Pompidou Centre in Paris, argues that though mud was the world’s dominant building material for 10,000 years, we have been ignoring it for the past 100 years. The walls of all our houses and public buildings might be made using substances extracted from the ground, but they are then mixed with chemicals and baked at extreme temperatures to make bricks or cement, and are often transported hundreds of miles.

Dethier long been a champion of building with earth straight from the ground – mixed with water and shaped into blocks and air-dried or simply built up in layers on walls – as an abundant, cost-free and environmentally friendly construction material.

France is a frontrunner in hempcrete, a biocomposite material containing hemp. Recently, the first public building in France made from hempcrete was completed, a 380-square-metre sports hall in the town of Croissy-Beaubourg near Paris.

The Danish company REXCON System is working to minimise industry’s climate impact with its modular, foldable building block, ReBLOCK, for constructing outer walls. The blocks are made mainly from plywood, with a galvanised steel profile and a cement-bonded particleboard to protect against the outdoor climate. ReBLOCKs are joined mechanically and are designed for multiple disassembly and reassembly. This is beneficial from a circularity perspective, as it enables the reuse, refurbishment and recycling of the blocks and materials.

Their foldability makes ReBLOCK more efficient during transport. For example, building blocks for a 140-square-metre house can fit onto six EURO pallets – a huge savings in transport resources. REXCON System is also working on establishing business models for product take-back to further increase the circular potential of the blocks.

The ability to change a building’s functionality using available secondary materials and biobased materials as much as possible was the aim in the design of Swettehûs, a new bridge control centre in the Dutch province of Friesland, where Sweco provided circularity advisory services. This resulted in a 2,300-square-metre building that was flexible and adaptive.

Swettehûs, Circular construction, by GEAR Architecten

Swettehûs, Circular construction, by GEAR Architecten

“To realise the building, we ensured that all parts of the structure could be disassembled, and that we built in a demountable way,” says Jan Dijkstra, structural advisor at Sweco. “A demountable building makes moving, changing or reusing building parts much easier. Another sustainable choice that has been made is the use of as many secondary materials as possible, preferably from Friesland itself, in order to emit less CO2 through short transport distances.”

Material in focus: 3: Sustainable infrastructure – the road to negative carbon

The Dutch province of Zuid-Holland has opened its first carbon-negative road, thanks to a collaboration between the construction contractor and Sweco. The N211 runs between the cities of The Hague and Poeldijk. The piece of infrastructure has 20 different sustainable innovations that save energy and carbon emissions

The construction works and maintenance of the N211 has led to 4,000 tonnes of CO2 emissions, while 14,000 tonnes of CO2 emissions were saved and compensated for during the construction and life cycle of the road. This is made possible by means of the sustainable measures that were taken during the developmental phase of the N211. Examples of sustainable innovations include sustainable heat generation through the bicycle lane, asphalt that is produced at a lower temperature, dynamic systems that dim the lighting when there is little traffic and the use of geopolymer tiles instead of cement to build the bicycle lane.

“We did not bet on one horse,” says Floor Vermeulen, deputy of Zuid-Holland. “The carbon emissions that we managed to save or compensate was not made possible by one great promising innovation. It was made possible by one integral approach in which some of the implemented innovations were tested but weren’t yet ready for the market. Zuid-Holland as a pilot customer has given these innovations the last push for them to be market-ready.”

Material in focus 4: Circular water management systems

A 50% increase in demand for urban water is anticipated within the next 30 years. Rethinking urban water systems through the circular economy and resilience principles offers an opportunity to tackle water challenges by providing a systematic yet transformative approach to supplying water and sanitation services in a more sustainable, inclusive, efficient and resilient manner.

“The two hottest tracks in the field of water among start-ups right now are digital water and circularity in the water system,” says Maria Sätherström Lantz, founder and CEO of WIN, an organisation that matches innovative start-ups with industrial companies in water, safety and energy.

Digital perspective: Digital water systems

Digital water systems use sensors to get a holistic overview of everything from consumption and quality to leakage and circularity in water management systems. This enables local stormwater management or adjustments to water quality as needed instead of using drinking water as today.

The Swedish start-up Graytec has developed a circular greywater recycling system called the Blue Circle System. It collects greywater from showers, bathtubs and sinks, purifies it to achieve drinkable quality, and then returns the purified water directly to those same showers, bathtubs and sinks for reuse. Graytec has also created the Blue Eco System, which redirects greywater for toilet flushing, laundry, irrigation and landscaping.

Reusing wastewater on industrial sites

Instead of using drinking water and groundwater in an industrial company, reused wastewater from industrial processes can be used to produce demineralised water. Using membrane technology, a minimum of chemical addition can be applied. The small footprint of the installation enables easy implementation and creates a virtually endless source of water. Reusing the wastewater not only leads to a reduction in water consumption and water discharge, but a reduction in chemical consumption and chemical discharge that has a major positive impact on the environment.

“Technological developments have made it possible to reuse all types of water. The big challenge that remains is to maximise wastewater reuse without complex technology,” says Steven Raes, bioengineer in environmental technology at Sweco.

For an industrial plant, Sweco was able to reduce water consumption and salt emissions by selecting the appropriate technology for water production and wastewater reuse:

  • 18% reduction in water consumption and discharge
  • 93% reduction in salt consumption and discharge

Europe’s first drinking water from industrial wastewater

It is ironic that Öland, Sweden’s second largest island, has long struggled with problems related to drinking water access.

“The situation was urgent,” says Peter Asteberg, project manager for a recently built waterworks in the Mörbylånga region on Öland. “We had previously been drilling for groundwater but without results. And then we realised that we have to find raw water that does not rely on rainfall and groundwater formation.”

The raw water he is referring to consists of brackish seawater and industrial wastewater from a local food producer, which were purified together. Brackish water was taken from nine coastal wells along the Strait of Kalmar, and the process water from a wastewater treatment plant. Different technologies were used, including ultrafilter and reverse osmosis. Simply put, these are various filtration techniques that use disinfection with ultraviolet light. The waterworks is the first in Europe to produce drinking water from industrial wastewater, and probably first in the world to combine this with desalination.

Mörbylånga, previously in dire straits, has now secured a stable drinking water supply for a long time to come through the new waterworks, and can now also call itself a forerunner in circular water supply.

The need for a circular systems mindset

Scaling up the impact of circularity requires a move from individual projects to a systems mindset.

“A lot of the existing initiatives focus on efficient use of resources, because many of our clients can do it themselves,” agrues Kathleen Van de Werf, Business Development Manager at Sweco. “But for a bigger impact larger, more collective infrastructure investments are needed.”

“It’s not any more about the products and the resources, but about new profitability models and a behaviour shift.”

One thing we need to increase the level of circularity is the integration of networks.

“Five or ten years ago, we had the master plan, we showed what the space would look like. Today, we’re a partner in the transition, we’re guiding, we’re detecting different actors, we’re showing what the possibilities are by dialogue models, we’re trying to come up with a coalition of stakeholders.”

“Service and logistics need to be organised commonly, not individually. The evolution of spaces is so slow compared to the evolution of technology.”

In some cases, it involves demonstrating the potential in a specific location, as in the case of the pilot project Potterij in Mechelen, Belgium. The development of a circular city lab measuring 800 square metres included broad participation from the city, external partners, neighbours and civil society organisations.

Potterij in Mechelen, Belgium

Potterij in Mechelen, Belgium. Section illustrating the redevelopment of former industrial site into a hub for social economies, creative make-industry and bottom-up circular initiatives. Client: OVAM Public Waste Agency of Flanders, Team: BUUR part of Sweco with partner MISS MIYAGI. Visualisation by Claar.

Conclusion and summary

No doubt remains that the circular economy will be part of our future, and a vital factor in the necessary shift. In Europe, the European Commission is working to achieve a carbon-neutral, sustainable, non-toxic, and fully circular economy by 2050. For the construction sector, the Circular Economy Action Plan stipulates that 70% of all waste must be recycled starting in 2020.

However, political incentives aren’t enough.

Industry needs to move faster – and smarter. In this report, we place the spotlight on a host of new, innovative ways to achieve a circular construction sector, through reuse, repurposing, recycling and closing loops. We also highlight the need for a circular systems approach, which considers not just individual projects but embraces collective initiatives with all relevant stakeholders. In our view, achieving the highest levels of circularity demands a complete mindset shift.

Steps towards this mindset can be made by taken the opportunity to integrate new innovations regarding digitalisation and materialisation into projects. And by doing this, creating new standards in process steps, roles and responsibilities.

References