According to research by EPFL, technologies already available could reduce the climate impact of building materials by 73 percent by 2050.

Driven by population growth and the rapid development of the countries of the global south, theglobal urban expansion is advancing at an unprecedented pace. This massive wave of construction, however, risks overwhelming climate goals, given the enormous environmental impact of traditional building materials.

A new international study from EPFL's Building Materials Laboratory sheds a light of hope: decarbonize the sector by 2050 It's also possible by building like never before. And to do so, the technologies we already have at our disposal may suffice.

Growing global population and resulting emissions

The demands of a growing and urbanizing global population are pressing on a strained and increasingly warming planet, which is depleting some of its most crucial resources (at least from a human perspective). According to some estimates, to meet the new housing and structural needs, we should build the equivalent of New York City every month. In addition to the people who will come, there are also more than one and a half billion individuals who still live in inadequate housing and who should be guaranteed access to basic services and infrastructure.

Considering that the production of building materials already contributes today up to 17% of emissions Given the anthropogenic CO2 emissions, this scenario is certainly worrying. The growth of cities, which will occur especially in low- and middle-income countries, will inevitably lead to an increase in emissions. Scientists are therefore beginning to wonder whether it is possible to contain the impact of this urban development and what the prospects are in terms of decarbonization.

An international team of researchers, including those from the Laboratory of Construction Materials (LMC) at EPFL's School of Engineering, conducted a study that reframes this issue by examining alternative development paths. The researchers found that the use of concrete and steel increases with development and then stabilizes once infrastructure is established.

"This means that the way materials are designed, produced, and recycled during growth periods has a huge impact on long-term emissions. Our findings suggest that improvements in these areas can already lead to significant reductions in carbon emissions."

has explained Karen Scrivener, head of the LMC. This would therefore be the best time to act.

Emissions: -73% by 2050 with existing technologies

Today, the study states, structural materials – that is, those based on concrete, steel, bricks and wood – they constitute approximately 93% of all construction materials by mass and are responsible for approximately 87% of CO2 emissions from the construction industry. Cement-based materials alone account for approximately three-quarters of the total. If we aim to decarbonize construction, in essence, we can only look at the concrete.

Previous studies have modelled the prospects of decarbonisation of building materials over the next few years, concluding that a reduction in emissions is a very achievable goal, given the application of some mitigation strategies: some reference research speaks of a possible reduction of 49-62% by 2050These studies, however, focused primarily on buildings, neglecting infrastructure (which accounts for about 40% of structural steel and 33% of concrete), and proposed solutions that were expensive or difficult to implement.

The new research, published in Nature Communications., instead, aims to understand what degree of decarbonisation we can achieve"using easily implementable, already applicable strategies within the materials and construction value chain”. And according to their findings, adopting the best construction technologies already available could reduce carbon emissions from concrete- and steel-based materials by approximately 73% compared to the current scenario.

More efficient design and low-emission concrete

By 2050, the world will have just passed peak cement consumption and will be just a few years away from peak steel consumption. Based on current trends, cement consumption will be between between 5 and 15 gigatonsWood, however, is not an alternative since demand will far exceed the amount of material that can be sustainably obtained.

Rather, the researchers indicate, among the technologies to be adopted, a more efficient structural design and concrete production practices that reduce waste, but also a greater use of steel and concrete recycling powered by renewable electricity. Another priority is the clinker replacement with low-carbon cementitious materials.

To reach the Net-Zero target, however, emissions still need to be reduced by 30%. Most current scenarios, the researchers explain, predict that this gap will arise from carbon capture, utilization and storage or from the use of hydrogen produced by electrolyzing water using excess electricity generation from renewable sources. Carbon capture and storage, however, costs between $60 and $130 per ton of clinker (increasing the cost by 2-4 times). These solutions, in short, are very expensive and involve "significant technological, implementation and social challenges".

Our work suggests that large-scale decarbonization of building materials is technically possible, alongside the expansion of housing and essential infrastructure, with the right policies. The coming decades represent a crucial period for updating standards, enabling material-efficient design and the use of low-clinker cements, as well as for extending practical solutions to low- and middle-income countries, where future demand will be concentrated.

concludes Alastair Marsh, a LMC researcher among the authors of the study.

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