The list of digital innovations that can be applied to the construction sector, one of the most impactful on the environment, is long and varied. Digital twins, artificial intelligence, materials passport, robotics, blockchain technologies, and reverse logistics are just some of the technologies that can help decarbonize the built environment and design increasingly durable and circular buildings.

Renewable Matter interviewed Catherine De Wolf, Assistant Professor at the Swiss Federal Institute of Technology Zurich (ETH Zurich) as well as co-author of A Circular Built Environment in the Digital Age (Springer, 2024). An open access publication ‒ over 27 thousand downloads in first week ‒ designed to reconstruct the state of the art of digital technologies that can be applied in construction, but above all to disseminate real-life case studies for experts and new students of architecture and engineering alike. After all, "demolishing buildings is a design mistake."

Professor De Wolf, why do we need circular buildings?

First of all, 40% of all our greenhouse gas emissions come from buildings, and a third of these are from the materials from which they are constructed. If we reused building materials instead of extracting virgin raw materials ‒ polluting again ‒ we would have a huge positive impact on the climate crisis.

Secondly, the sector generates too much waste. More than a third of all waste generated in the European Union originates from the Construction and Demolition sector. Lastly, we are depleting many resources. For construction alone, we extract 40 billion tons of sand each year, one of the ingredients in cement. One might argue, "Well, but we have enough sand in the desert." Except that is not precisely the case, because that one is too fine. Sand as a building material is mined in riverbeds. This creates a lot of problems, for example when it comes to biodiversity. Not to mention illegal mining and the phenomenon of sand mafias.

Is there a need for traceability, then?

Tracking and tracing materials is one of the key principles of the circular economy, and construction is one of the sectors with the least labor traceability. Unless we know where the materials we use for our buildings come from, we cannot know how they were extracted, or whether they were subjected to forced or child labor. The construction industry is quite prone to forced labor.

It is estimated that globally most construction companies do not have a payroll, making it very difficult to track whether it is ethical labor or not. In contrast, in a circular economy model, we typically source locally. So, it is much easier to track and verify that there have been no human rights violations along the supply chain.

Nevertheless, the circular economy in construction is not an entirely new model throughout history.

We have been building circularly for centuries, just think of the stone in the Colosseum, which was reused to construct so many other buildings in Rome. Reusing materials, in the past, was considered normal. Eventually, we stopped because we needed to build faster and higher and we had fossil fuels, which made it extremely easy to extract and transport materials from far away.

How to move away from the linear model?

We cannot ask people to stop living or working in buildings. So, we have to improve them and build them in a circular way. However, if we want to be competitive with the linear way, we have to make circular construction more efficient, cheaper, and faster. And that's where digital technologies come in. After all, if you use the power of artificial intelligence and big data, you can track and trace materials and make it easier to find and reuse secondary raw materials.

Also, now with computer vision you can inspect materials more easily, turn them into BIM models [Building Information Modeling, author's note], and create catalogues to choose from. Real platforms for the circular economy. Before, all this was done manually. Then, digital fabrication techniques are being developed that can 3D print connections that fit the available materials.

Which digital technology is more "disruptive" than others?

I don't think there is one that is more disruptive than the others. I think each of them brings something different to the table. Of course, artificial intelligence has huge potential in many different ways, but so does blockchain for traceability and commerce. I think digital fabrication still needs some development. On the other hand, there is a lot of potential in the field of robotics, which is progressing but at the moment is more at the prototype level. I believe that in a few years, we will be able to build in a safer, faster and more accurate way.

Speaking of eco-design, the Environment Committee of the EU Parliament is working on the new Ecodesign for Sustainable Products Regulation (ESPR). What are your thoughts on it?

The advancement of regulations is crucial because alone the market would not be fast enough. Regarding material passport regulations, I think they are fairly easy to implement, meaning that when you are building or renovating, there is already a system in place that requires permits, and you can make sure that they are only granted if you track and trace the materials. The ESPR package will only drive the industry to make circular construction technologies more efficient in a shorter time frame.

How important is it to disseminate case studies to accelerate the ecological transition?

The teaching and transfer of knowledge are crucial, as is raising awareness. For example, in my teaching activities, what we try to change is the way new architects and engineers design buildings so that they consider the principles of the circular economy.

Demolishing buildings is a design mistake. If you design correctly from the beginning, you can reuse, repair, reuse. Therefore, I think it is important that there is this mindset shift in designers, but also in the citizens themselves and the users of buildings. Circularity is something that has to become more and more important in the purchase and use phase of the building.

This article is also available in Italian / Questo articolo è disponibile anche in italiano

Image : Nazrin Babashova, Unsplash

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