The United Nations develops maps to decarbonize the polluting construction sector

PARIS – The construction sector, the most polluting and hardest to decarbonize, must build less, use more sustainable materials and clean up traditional materials to cut its emissions, the United Nations said on Tuesday.

The industry is responsible for 37 percent of global carbon dioxide emissions, and increasing urbanization is stimulating the construction of new buildings made of carbon-heavy materials, especially concrete and steel.

Booming urban environments – adding new buildings in an area the size of the city of Paris every five days – are damaging life-supporting ecosystems and posing serious challenges to the fight against climate change.

A report published by the United Nations Environment Program and the Yale Center for Ecosystems and Architecture on Tuesday called for the sector to prioritize a “circular” approach that avoids waste.

Dr. Sheela Agarwal Khan, Director of the Department of Industry and Economy at UNEP, said net zero in the construction sector by 2050 is achievable if “governments put in place the right policy, incentives and regulation to bring about the shift to industry functioning.”

Building less and reusing existing structures generates 50 to 75 percent fewer emissions than new construction, the report said.

She added that switching to renewable biomaterials such as wood and biomass could lead to emissions savings of up to 40 percent by 2050 in some regions.

Traditional materials that cannot be replaced – such as concrete, steel, aluminium, glass and brick – must find ways to decarbonise further, the report said.

Electrifying production, scaling up innovative technologies, and using more recycled materials will accelerate efforts to clean up these particularly carbon-intensive materials.

Concrete, aluminum and steel alone account for 23 percent of total global emissions.

The report recommended that the share of concrete in global construction should be halved between 2020 and 2060 in order to effectively decarbonize this sector.

Two-thirds of the concrete should be “circular” – that is, concrete that has been recycled, reused or made using low-carbon cement.

The rest will be new low-emission cement.

Professor Anna Dyson, lead author of the report and a professor at Yale University School of Architecture in the US, said the sector needed a “revolution”, including a “significant reduction” in the production of new concrete.

“But it will be gradual,” she told AFP.

Steel and concrete “often only give the illusion of durability, and often end up in landfills and contribute to the growing climate crisis,” Dr Aggarwal Khan said.