Definitions of low-carbon concrete announced at COP29 to "bring transparency and trust"

The Global Cement and Concrete Association has set international definitions for low-carbon concrete and cement, which were launched at the COP29 climate conference.

Announced at the COP29 summit in Azerbaijan, which took place from 11 to 22 November, the Global Cement and Concrete Association (GCCA) hopes its definitions will encourage the identification and sale of "green" concrete and cement.

Made from a combination of water, aggregate and cement as a binding agent, concrete is the second most commonly used material on the planet after water. It is widely considered to be one of the most environmentally harmful materials because of the highly energy-intensive production of cement, which generates large amounts of CO2.

Definitions for low-carbon concrete will "bring trust in the markets"

The GCCA created different bands of categorising low-carbon and near-zero-emission concrete and cement that could be used globally.

"In some locations, the purchased product at a construction site is concrete, and in others it is cement, so it is important to have definitions for both," GCCA concrete and sustainable director Andrew Minson told Dezeen.

"The definitions will bring transparency and trust in the markets and help governments and businesses identify and buy green cement and concrete," he continued.

"Stimulation of demand for low-carbon cement and concrete products through public and private procurement is a key lever for accelerating decarbonisation."

The GCCA set a global reference threshold for concrete by taking an average of what is considered good practice in concrete production in different countries.

From this, five bands of low-carbon concrete lettered from A to E and one category for near-zero-emission concrete lettered AA were defined. Additional bands F and G were added above the threshold to cover all concrete production.

Designed to be applicable to ready-mixed concrete, precast and masonry concrete elements, the categories are measured by comparing Global Warming Potential (GWP) units – the amount of embodied carbon dioxide equivalent per cubic meter – against the compressive strength of the concrete sample.

GCCA wants to "maximise involvement" of professionals using its definitions

Building upon research on cement production by the International Energy Agency (IEA), the GCCA also defined categories A to E for low-emission and near-zero-emission cement according to the ratio of cement to clinker, which is the main ingredient in cement and made at the kilning stage.

"For concrete, the GCCA has added F and an open-ended G so that no matter what the GWP, a band can be allocated to the concrete," he continued. "This widens application and is inclusive in an effort to maximise involvement."

"For cement, GCCA has not reinvented the wheel but has provided guidance on how the IEA definitions for production can be used for products using the well-established carbon reporting process in the construction sector."

By presenting categories of low-carbon concrete and cement as lettered bands, the GCCA hopes to make it easier for built-environment professionals to make more sustainable material choices.

"The banding enables project teams, clients and governments to communicate what products in terms of embodied carbon emissions (ECO2e) are to be procured or supplied and, post-construction, what products were used in the project," said Minson. "This enables comparison with targets set."

"The banding has advantages over the direct use of ECO2e values from Environmental Product Declarations because they are consistent between countries and are comprehensible and accessible to construction professionals who are not concrete experts."

According to Minson, the GCCA definitions could also be applied to regulations for low-carbon construction.

"We expect these definitions to be used in public procurement and would expect them to be used in regulations," he said.

"Regulations and enabling policies are key to helping the industry achieve its net zero mission."

United Nations establishes new council to speed up decarbonising the built environment

Also at COP29, the United Nations Environment Programme's (UNEP) Global Alliance for Buildings and Construction announced the formation of the Intergovernmental Council for Buildings and Climate, which will carry out goals set by the Chaillot Declaration earlier this year.

The council was established to help speed up efforts to decarbonise the building industry, which UNEP claims is responsible for 37 per cent of the world's energy-related carbon emissions.

Research into low-carbon concrete that has been published on Dezeen includes a recycling "breakthrough" that uses waste cement from demolished buildings and algae-grown limestone that can be used to make carbon-neutral concrete.

The top image is by Rafael Gamo, Young & Ayata and Michan Architecture.

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