Article - Why circularity matters in building materials |
Decarbonizing construction

Why circularity matters in building materials

Contact image written by Louise Sundström, Brand Planner, Skanska Group written by Louise Sundström, Brand Planner, Skanska Group

As industries all over the world move toward sustainability, building materials have been thrust into the spotlight. The population is growing and infrastructure is needed to support it. But the built environment is a major source of CO2 emissions, around 40 percent. Many of these emissions are produced when new materials are manufactured, such as cement, steel and glass.

The best way to combat these harmful emissions is by embracing the concept of circularity, which involves finding ways to reuse materials after their initial life cycle comes to an end.


Many experts in the field have made the development of sustainable solutions their focus. Lena Hök, Executive Vice President for Sustainability and Innovation with Skanska, Magali Anderson, Chief Sustainability and Innovation Officer at Holcim, and Emmanuel Normant, Vice President for Sustainable Development at Saint-Gobain, are leaders with much to share. They discuss circularity, innovations — particularly in cement and glass — and what’s next for sustainable building materials. 

A focus on responsibility from the get-go


Reducing carbon emissions is a priority for Skanska. Increasing use of circular materials – recovered and reused beyond their initial use phase – can dramatically reduce the emissions from the construction of a building or project. 


One example is Skanska’s low-carbon asphalt. By using biofuels and renewable energy rather than fossil fuels, and by incorporating recycled asphalt in the production process, this product releases far fewer carbon emissions than normal asphalt.  


It’s essential that large construction companies like Skanska are involved early on in planning discussions; there must be an understanding of the importance of sustainable materials from the get-go. Builders need to realize the carbon impact of the materials they use: to aid in this work, Skanska has created the Embodied Construction Carbon Calculator (EC3) so that architects, engineers and other experts can compare different materials and their respective carbon footprints.  


It’s all about having the expertise and knowledge of how to use these materials and scale them. Tools like the EC3 can be helpful for organizations that want to build sustainably. When you start with environmentally-friendly materials, you’re one step further to creating net-zero constructions.


Low-carbon concrete: an important innovation


Both construction companies like Skanska and material suppliers play a huge role in developing low-carbon materials. Holcim, a leading wholesale building materials supplier, created a sustainable concrete called ECOPact and a lower-carbon cement called ECOPlanet. The company has a focus on sustainability and renewable energy, and it is constantly working toward net-zero materials. 


In normal cement production, every kilogram of cement produces nearly one kilogram of CO2. And the production of 1000 kg of concrete releases around 900 kg of CO2. Cement and concrete production are significant sources of carbon emissions. 


That said, it is possible to reduce CO2 in cement production. One way is to replace the fossil fuels that are used to heat the kiln where the cement is made with recycled waste and biomass. Another way is to replace the clinker, a mix of limestone and minerals that is also heated in a kiln. Clinker is the main ingredient in cement and is directly linked to the carbon emissions generated in manufacturing. 


Holcim uses both these methods to make a more circular product. Its ECOPact concrete has a circularity of 24 percent, whereas the industry standard is 8 percent — making ECOPact three times more circular than traditional concrete. At one plant in Altkirch, France, Holcim created a clinker made from 100 percent recycled materials. And last year, Holcim used 54 million tonnes of waste in its concrete and cement production. It doesn’t get much more circular than that.


Glass production revisited


Another material that is responsible for significant carbon emissions is glass. It’s typically made by heating limestone, ash and sand to extremely high temperatures. Glass production is responsible for 22 million tonnes of CO2 in Europe each year and 95 million tonnes worldwide. It’s an enormous source of carbon emissions. 


Saint-Gobain is another building materials supplier. It has been around since the 17th century and, like Skanska and Holcim, it is working toward reducing its carbon emissions. The company has a goal of becoming carbon neutral by 2050. A large part of this involves analyzing the life cycle of its materials to make them more circular. 


Saint-Gobain has discovered that it is possible to produce glass without CO2. By replacing virgin materials needed to produce glass with recycled glass (called cullet), it is able to reduce direct emissions by over 60 percent. More recently, Saint-Gobain experimented with 100 percent recycled glass, biogas and clean electricity over the course of one week. It was a phenomenal success and it is working towards replicating the process on a larger scale.


Life-cycle analysis plays a major role in Saint-Gobain’s work to make its manufacturing more sustainable. It’s a method used to evaluate the environmental impact of a product through its production, use and eventual disposal. Embodied carbon – the carbon emissions associated with the materials, processes, manufacturing and transportation required to produce a product –  is a central component in this analysis. 


By 2030, Saint-Gobain hopes to perform life-cycle analyses that are third-party verified for all of its product lines. It plans to release its findings to the public so that similar suppliers can benefit, too.


Looking toward the future


Skanska, Holcim and Saint-Gobain are great examples of what building materials suppliers and construction companies can do to help their peers move toward sustainable manufacturing. The key is knowledge-sharing and understanding how you can build upon that knowledge and apply it. 


Many of the innovations that we need for tomorrow are already here — what’s needed is the willingness to learn how to scale them. The organizations mentioned are just a few that have been working toward the goal of net-zero construction. Low-carbon construction can contribute to better health and stronger resilience for society. 


If you’re in the built construction space, consider prioritizing sustainability. You can use your products to contribute to a better world — and one that can support generations to come.


Listen to the first episode of the Shaping Sustainable Places podcast and subscribe for more episodes. Learn more at Foresight Hub.