How much CO2 does the construction sector produce?

Combined, construction and infrastructure account for about 40 per cent of global emissions, so it is already a massive amount. And then you have to consider how the world’s population is increasing and how societies are changing. It’s not just more houses and offices; it’s bigger houses and bigger offices.

Roughly, by 2050 the square meterage that exists today will have to double. As we move through the 21^st century, yes, the footprints of cities will spread, but they will also become taller and denser.

Obviously, that is good for the construction sector, including steel producers like ArcelorMittal. But it’s a massive challenge for humanity because if we continue to build the way we’re building, we’re going to run into a wall.

So how do we avoid that wall, while maintaining economic and social development?

Fundamentally, we need to change our approach to construction, to change the way we use materials.

In some parts of the world, we are seeing signs of this happening - a change of mindset by real estate investors, by architects, by construction companies to focus on decreasing the carbon intensity of building. But it’s not enough. We need to rethink the way we build, to make buildings more flexible, more adaptable.

Today, we destroy huge numbers of buildings, not because they are structurally unsound but simply because they no longer meet the requirements of the market, of the user. We need to design buildings that can adapt to changing use patterns in order to extend their lifespan.

Adaptable buildings? What does that look like in practice?

Take an office building. One means of construction is using mainly concrete, with the internal architecture being part of the structure. But what happens in 10 years’ time when another tenant comes along and decides they don’t want single offices, they want open plan? If walls are load-bearing, that’s a major problem. Similarly, with the façade. If the façade is part of the structure, you can’t change it.

But if you use steel as the superstructure, you’re separating the functions and removing this. You have the frame with really large, free span columns, and you have plugins like the façade or the internal layout. If you want to change them, you don’t have to destroy the entire building. The tenant can do what he wants – so the building lasts for much longer.

But longer-lasting buildings won’t address the emissions from all the new ones we need, right?

No, that’s why we also need to rethink the materials we use, in particular high-strength steel. It sounds a bit odd for a steel producer to say ‘use less steel’, but high-strength steel allows you to cover the same span while using significantly less material. Compared to conventional steel, the savings are up to 40 per cent.

And then when you combine that with low-carbon steel, the total emissions savings can be 80 to 90 per cent. You’re reducing the carbon footprint of the structural part of the building by a factor of nearly 10.

Low-carbon steel? Tell me a bit more about that. How is it made?

Low-carbon steel, like ArcelorMittal’s XCarb® Recycled and Renewably produced (‘RRP’) range, is essentially scrap metal melted down and recycled in an electric arc furnace. If the power is coming from renewable sources, it’s very efficient from the perspective of CO₂ emissions.

Learn more about XCarb® low and zero-carbon products and steelmaking activities

What about the economics? Surely high-strength, low-carbon steel is going to be more expensive?

Of course, on a one-for-one basis, high-spec XCarb® RRP steel is slightly more expensive. But that’s not the way to look at it because when you combine it with high strength steel, you are using significantly less material. That means for the bill for the whole building will be much cheaper. For the construction companies, for the investors, it’s a no-brainer.

Depending on factors like the design and the architecture, the costs of using XCarb® RRP steel in a building will be between 1 and 2 euros per square metre more expensive. Just think about how that compares to the carpet or wood they’re going to put down on the floor.

The economic argument sounds compelling. What about regulation? How important is that?

Of course, along with the carrot, you have to have the stick. Big construction companies, especially the listed ones, are under pressure from their investors to decrease their carbon footprints, as part of their commitments to corporate social responsibility.

But they’re not the majority of the market. For smaller operators, you need regulation to force changes in behaviour. And we’re starting to see that. In Europe, for instance, there are rules limiting the amount of carbon permitted per square metre built – and this limit is tightening, in some countries we are moving from 1000kg of CO₂ per square metre built in 2023, to about 600kg of CO₂ by 2030.

We’re also starting to see similar initiatives in Australia, Southeast Asia and North America. There are regulations in California under the Buy Clean California Act, and other states are starting to catch on.

Are there any other ways ArcelorMittal is helping drive this change?

We launched an initiative in 2019 called Steligence®. It helps an investor, an architect, an engineering company to optimize the entire building using steel and other materials. It also helps construction companies to look at the steel requirements of the whole building, not just the individual components.

If you optimize each individual component, you will never end up with the optimum building.

The Steligence^® philosophy, based on a scientific approach to construction which considers buildings holistically, encouraging collaboration between various specialisms.

At ArcelorMittal we offer every single piece of steel you’re going to need for a building – beams, plates, light-gauge framing, tubes, façades, ventilations, you name it. But with Steligence®, we’re not thinking about individual products, we’re thinking about the overall steel requirements of the building: what is the best steel solution for the project.

When we combine this sort of intelligent, super-efficient design, with high-strength, low-carbon steel, we really are making an enormous difference. The Eiffel Tower is a work of art, not a building. But if we were building it today, the carbon footprint would be one tenth what it was back in 1889.

How has Steligence® been received by the market since its launch in 2019?

Steligence® has been really well received by the construction market. Today, thanks to our change of strategy from individual components to the whole building, we can have really meaningful conversations with real estate investors and architects that are interested in the building scale level. We have been involved in more than 2,500 projects of varying scales.

It is difficult to choose some to highlight because the range is really large, but we have participated in several football stadiums from all over the world including the refurbishment of the Real Madrid in Spain, the Yamoussoukro stadium in Ivory Coast which was use for the last African Cup of Nations football tournament and the new 15,000 seater SC Cambuur stadium in Leeuwarden in the Netherlands which is the first stadium in the world to use XCarb® RRP.

We have also delivered hundreds of bridges, often using our Arcorox® steel, which is a weathering steel that offers excellent corrosion protection meaning you don’t need to paint the steel. And of course, we have worked on a large range of buildings - large storage halls, data centres, most of the new electric cars and battery manufacturing facilities which are being developed in Europe.

We are also active in the tall building segment. A great example is the project Atlassian in Sydney, Australia. The building is 183 metres in height and will be the tallest steel/wood hybrid structure ever made. It is currently in construction and will use more than 2000 tons of Histar® and XCarb®.