Although investment in the energy efficiency of building operations increased 16 per cent among Group of Seven countries in 2021, such commitments “pale in comparison” to what is required to decarbonise the built environment, it added.

“Net zero in the building and construction sector is achievable by 2050, as long as governments put in place the right policy, incentives and regulation to bring a shift in industry action,” said Sheila Aggarwal-Khan, director of UNEP’s Industry and Economy Division.

Decarbonising the sector requires cooperation across multiple stakeholders throughout the building life cycle to bring down emissions associated with the construction and deconstruction of buildings, and those generated through the function and maintenance of these buildings, the report said.

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Building less and repurposing existing structures could help generate 50 to 75 per cent fewer emissions than new construction, the report said. The report also suggested construction with less materials, and with materials that have a lower carbon footprint and facilitate reuse and recycling.

Switching to ethically and sustainably sourced renewable bio-based building materials, including timber, bamboo and biomass, could lead to compounded emissions savings in many regions of up to 40 per cent in the sector by 2050, it added.

For conventional materials that cannot be replaced, especially concrete, steel and aluminium, which together are responsible for 23 per cent of overall global emissions currently, priority should be placed on powering production with renewable energy sources, increasing the use of reusable and recycled materials, and scaling innovative technologies, according to the report.

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Decarbonising the construction sector also requires changing the common perception of concrete and steel as modern materials of choice, it said.

“Until recently, most buildings were constructed using locally sourced earth, stone, timber and bamboo,” said Aggarwal-Khan. “Yet modern materials such as concrete and steel often give only the illusion of durability, usually ending up in landfills and contributing to the growing climate crisis.”

The share of concrete in global construction needs to be reduced by half between 2020 and 2060, the report said.

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China, the world’s largest carbon emitter and producer of construction materials, has a huge role to play in decarbonising the global construction sector, the report’s authors said.

Since the mid-2000s, China has built the world’s largest in-use cement stocks, with 80 per cent going towards the construction of buildings and the rest towards infrastructure to meet the needs of an expanding middle class, according to the report.

“China, as the largest global emitter in the real estate development sector, has a huge opportunity to demonstrate ethical decarbonisation,” said Anna Dyson, a lead author of the report and professor at the Yale School of Architecture.

“We need to make a relationship with China and hopefully coordinate the certification between fair labour practices and ethical decarbonisation. This is a tremendous opportunity that could be offered to the sector.”