Less than 10% of new construction in France is made of low-carbon concrete

Question: As the first low-carbon construction fair opens in Paris, what is the state of affairs in France?

ANSWER : “Today in France, less than 10% of new construction uses concrete which has a lower carbon footprint than conventional concrete, these remain niche even if there are many pilot projects everywhere.

But this will grow rapidly with the RE2020 environmental regulation in force since January 2022. It imposes CO2 standards per square meter built, binding and evolving with emission thresholds which decrease until 2031.

France is the first country in the world to have legislated on the subject, and we have felt a real acceleration on construction sites over the past year, also because contractors and developers are demanding low carbon, even if it is more expensive. ".

Q: What technique can be used to reduce the carbon footprint of concrete, which alone represents 7% of CO2 emissions on the planet, therefore more than aviation according to the UN environment?

A: “The first way is to use less emitting cements (The “clinker”, the cement binder, and its main constituent, resulting from the cooking of a mixture of limestone and silica at 1.450°C, is responsible for more than 90% of the carbon footprint of cement, Editor's note).

We need to find products that add resistance to the building but are less emissive than clinker. The best known is steel slag, a waste product from the cooking of steel. But the steel industry is also changing technology to decarbonize its processes, and we will have less and less slag available.

Other solutions that are emerging are the use of calcined clay fired at low temperature, metakaolin or fly ash. We are also looking at certain adjuvants which make it possible to reduce the quantity of cement used. Start-up solutions like Hoffmann Green, which offers very, very low-emission concrete, are interesting, but their volumes are too low. The challenge is to decarbonize en masse.

What also matters is reducing the amount of concrete used. It is possible to reduce it by optimizing construction systems, for example lightening floors by using wood. The solution will be to use it intelligently.”

Q: Is it possible to do without concrete by 2050?

A: “There will be less of it in housing, but it is irreplaceable for foundations, dikes, dams, wind turbine masts, bridges, power plants, large infrastructures. In about ten years I believes that more than half, approximately 60% of concrete, will be low carbon in France, that is to say with at least 30% less CO2 emissions than currently.