Thought LeadershipFebruary 3, 2022

A circular approach to construction

Sustainable building approaches drive positive change
Avatar Alex Smith

Constructing and operating buildings is one of the largest single contributors to global emissions of greenhouse gases. Low-carbon, modular and circular solutions for net-zero buildings, cities and nations are helping to tackle the problem – especially with virtual technologies that improve humanity’s ability to plan, evaluate, build and monitor the results.

While the world’s metropolises occupy just 3% of the Earth’s land, they account for up to 80% of energy consumption and 75% of carbon emissions – and the pressure is on for cities to achieve a better balance.

“The built environment is referred to as the ‘sleeping giant’ because of its large footprint and insufficient action to tackle energy consumption and carbon emissions thus far,” said Roland Hunziker, director of sustainable buildings and cities at the World Business Council for Sustainable Development (WBSCD). “When we talk about built-environment emissions, we are referring to emissions that are caused by the places in which we live and work, as well as the infrastructure around that. We look at both the emissions during the use of buildings, as well as during the construction process itself.”

The giant is being urged into action. For the first time in six years, the built environment figured prominently on the 2021 agenda of the United Nations’ COP26 climate change summit. And C40, the network of mayors of nearly 100 world-leading cities, ran its “Our Last, Big Chance” event, showcasing why the future depends on action taken today in the world’s cities.

McKinsey Global Institute estimates that digital solutions could improve some quality-of-life indicators in cities by as much as 30%. (Image © Adobe Stock / babaroga)

While automobile makers can switch to electric propulsion and packaging companies can stop using plastic, massive cities already exist – only upgraded as needed and at a very slow pace – and are under tremendous pressure to grow at almost unprecedented rates. So how can planners, developers and governmental officials reduce the impact of what is already built while moving construction to a more sustainable trajectory in a time span that can be counted in years or decades and not centuries?

Although the challenge is being tackled in many ways on many fronts, pioneering cities, construction firms and architects are leveraging virtual twin technology – scientifically accurate 3D computer models of existing and planned construction – to enable design for eco-efficiency; an evolution to manufacturing and assembly techniques that reduce waste; online collaboration that improves outcomes; and informed strategies for efficient operation.

In just one example – using virtual twins to operating existing buildings more efficiently – a recent study by Accenture, in cooperation with Dassault Systèmes, estimated the technology could reduce building operating costs by US$288 billion (€254 billion) by 2030 by reducing energy demand and eliminating 6.920 metric tons of CO2-equivalent emissions. However, the positive benefits of applying virtual twins to the built environment could be multiplied exponentially – and repeated year after year – by applying them to every aspect of construction.


For the construction industry to deliver its fair share of CO2-emission reductions, experts agree, change needs to happen in three key areas: reusing materials during production and construction, optimizing existing assets and operating existing buildings more efficiently.

“The first [change] is around circular production and construction,” WBSCD’s Hunziker said. “The built environment is not only a huge emitter of carbon; it also uses about 50% of global resources. That is unsustainable because it creates a lot of waste. We have to try to close that loop by reusing existing materials, or even [reusing] structures.”

Miguel Eiras Antunes, global Smart Cities and Urban Transformation leader at advisory and technology firm Deloitte, agrees.

“A circular approach ensures that material choices are considered that are reusable and recyclable and minimize virgin material use, and [are] sourced in a strategic and sustainable way,” he said.

Global construction firm Bouygues Construction is already making progress on this front. Improvements include a 40% reduction in the carbon intensity of its concrete, thanks to a new formulation of mineral compounds. In Europe, Bouygues also constructs 30% of its buildings of sustainable wood, and 90% of its vehicles will be green by 2030. To reuse building components, which enables circularity, Bouygues employs 3D virtual twin models and databases to facilitate and streamline the process.

“Virtualization, using an enterprise-wide platform, heralds a more integrated organizational approach that allows in-house control over every aspect of our work,” said Fabrice Bonnifet, director of sustainable development at Bouygues Group. “That means design, manufacture, transportation and assembly of building components can be optimized and standardized. [For example,] digital technology is enabling us to build factories that can manufacture 2,000 modular apartments per year that are quick, clean and easy to assemble at the worksite.”

“We’ve found that digital twins of the physical built environment in cities, for example, can help reduce operating costs by 35%, while at the same time boosting productivity by 20%.”Miguel Eiras Antunes
Global Smart Cities and Urban Transformation Leader, Deloitte

Bouygues also maintains a digital databank of reusable and salvageable components. “At the end of a structure’s life, these parts will be used again in other, future buildings,” Bonnifet said.

Like Bouygues, New York City construction start-up Assembly OSM devised an approach to construction that fundamentally transforms the design and delivery of its buildings. Assembly OSM’s advanced software platform creates a digital thread – much like those used to design automobiles and airplanes – to develop custom high-rise buildings as manufactured products. Phases managed by the platform include system design, project architecture and engineering, fabrication and manufacturing, logistics, assembly and delivery.

“Using information as the lifeblood of our process, our platform creates unmatched efficiency and transparency for all teams and partners,” said Andrew Staniforth, CEO at Assembly OSM.

Assembly OSM reports that its approach reduces the timeframe of a project by 50%, cuts its embodied carbon footprint by 40% and delivers certainty to developers by mitigating the generally unpredictable nature of construction.


The UK’s Green Building Council estimates that 80% of the buildings that will exist in England, Scotland, Wales and Northern Ireland in 2050 are already built. Retrofitting and updating existing buildings, therefore, is the second opportunity for sustainability improvements in the built environment.

Robert Plana, chief technology officer at France-based engineering company Assystem, outlines the weight of the challenge.

“When you are looking at optimizing a greenfield city or site you are starting from scratch, so it’s far easier than trying to decarbonize a brownfield environment,” he said. “In the latter you have existing infrastructures and services already in place, and the areas are already populated. It’s not easy.”

Jean-Eudes Guilhot-Gaudeffroy, a digital engineering director at Assystem, said the key to overcoming those challenges lies in virtual twin technologies, which assess and optimize the sustainability characteristics of a building before construction. Modeling a building’s operations helps to identify improvements.

“Modeling a site using virtual twins helps us to simulate choices defined during the design phase and simulate the performance of solutions that favor sustainability, before they are implemented physically,” Guilhot-Gaudeffroy said. “This avoids disruption to the existing infrastructure and prevents disturbance to people already living in those areas.”

For example, Assystem uses virtual twins to assess the deployment of electrical vehicle (EV) chargers in a city, and the associated energy demands.

“The increased use of EVs will create a huge energy [demand] peak in the evenings,” Plana said. “This will place demands on the electrical grid. Using virtual twins, we were able to undertake a variety of ‘what if’ scenarios so that we could propose the most effective physical deployment of charging schemes featuring energy shaving and additional energy storage.”

Canadian public utility company Hydro-Québec also uses virtual technologies to optimize existing assets, including viable ways of converting existing fossil fuel-burning systems to clean power.

Romaine-4 worksite, dam (Image © Hydro-Québec)

“For example, artificial intelligence can be used to calculate the energy demand of assets more precisely, liberating megawatts of renewable energy that can be exported to our neighbors [and] displacing fossil fuel energy at the same time,” said Jean Matte, acting chief innovation officer and executive vice president for generation, health, safety and environment at Hydro-Québec. “We also use sensors in our installations to follow closely their behavior.

“For example, this allowed us to create digital twins of some of our assets. These twins – that have proven to provide reliable information over time – can help us understand more deeply how a certain asset will behave in the future.”


Sustainable operations represent the third opportunity to reduce the environmental impacts of buildings and cities.

“We need to address the emissions embodied in materials and equipment and the emissions from the energy used during the operational lifetime of buildings, so we need to work toward a total lifecycle assessment of all products,” WBSCD’s Hunziker said – a challenge where the analytics built into virtual twins of buildings, cities and utilities can be especially helpful.

“There needs to be accountability for the impact of all new buildings and renovations,” he said. “We can’t continue with the current trend of tearing down a building and then building something even bigger in its place without assessing the full carbon impact this generates.”

36 – 50 – 38

According to World Green Building Council, construction consumes 36% of global energy and 50% of resources, while generating 38% of energy-related carbon emissions – with a footprint that is projected to double by 2060.

Improving the energy efficiency of new and existing buildings is central to creating sustainable operations going forward.

“There is still a huge gap to close if we want to achieve the ambitious goal of carbon-neutrality in cities,” Deloitte’s Eiras Antunes said. “There is considerable scope for reducing emissions through energy efficiency and decarbonizing heating systems. For instance, it is possible to cut 90% of emissions from cities using proven technologies and practices by 2050, according to the Coalition for Urban Transition, and 58% of that reduction may come from residential and commercial buildings – it includes decarbonization of electricity and efficiency of resources.”

Assystem’s Plana believes that virtual twins will be particularly important in this effort.

“If we are to adequately and reliably supply renewable energy to cities, then we need to address the variability that comes from wind and solar supplies,” he said. “Cities that currently rely solely on these sources experience a lot of outages, and this isn’t acceptable.”

Robert-Bourassa development, spillway and dam (Image © Hydro-Québec)

Hydro-Québec’s research institute is working intensively on solving this challenge. “In recent years, our teams have developed a unique battery technology, which is very robust and can withstand large temperature variations,” Matte said. “Last year, we launched EVLO, a subsidiary that produces safer, and 99% recyclable, large-scale batteries.”

As a result, Hydro-Québec, through EVLO, can now store wind and solar energy for later use. “For example, we inaugurated a solar park last summer where we will store solar energy in our batteries and inject it when necessary into our main network,” Matte said.

German startup Kraftblock is among those eager to ensure a steady supply of renewable energy.

“Decoupling energy production from consumption by using storage is critical to the success of making the transition to renewables,” Kraftblock CEO Martin Schichtel said. “Making that storage mobile is essential to serve existing communities. At the moment, optimizing existing infrastructures can take up to a decade. There’s a lot of planning involved, and then there’s the physical pipework and so on that needs to be installed. At Kraftblock, we have designed a solution that can bridge the gap between designing the system and putting it into operation.”

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