Renovate and reuse: Building blocks for cutting construction emissions

Renovating rather than building new could cut up to three-quarters of embodied emissions from the buildings and construction sector globally a new report argues.

The report by the UN Environment Programme and the Yale Center for Ecosystems + Architecture describes three building blocks for climate action, designed to cut the embodied emissions associated with construction materials like concrete, steel and aluminium.

The built environment sector is responsible for 37% of global greenhouse gas pollution, according to ‘Building materials and the climate: Constructing a new future’.

“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 the industry action,” says Sheila Aggarwal-Khan, UNEP industry and economy division director.

The report says three urgent pathways are needed for the sector to achieve net zero emissions by 2050: avoid, shift and improve.

Avoid presents the greatest opportunity, the report argues. 

It says avoiding new builds and the use of new materials through careful design can reduce the extraction of new raw materials and limit the production of emissions-intensive materials. 

Renovating an existing structure rather than building new, can cut 50-75% of embodied emissions the report says.

Avoiding new materials by reusing or recycling construction materials can also make a difference in embodied emissions of at least 10-50%.

Shift, the second pathway, involves using sustainably and ethically sourced renewable construction materials like timber, bamboo and other “bio-based materials” instead of conventional ones. 

At scale, this shift could help the sector achieve a 40% cut in emissions by 2050. 

“Until recently, most buildings were constructed using locally sourced earth, stone, timber, and bamboo. 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,” Aggarwal-Khan says.

The third urgent pathway is about reducing the emissions from conventional construction materials, including concrete, steel, aluminium, glass and bricks.

Options detailed in the report include electrifying production processes and powering these with renewable energy, improving energy efficiency and changes in the materials and processes used. 

The key message for the building and construction sector is that climate action will need to shift attention from operational emissions – such as emissions associated with energy use in heating and cooling – to ‘embodied emissions’, those associated with materials like concrete, steel and aluminium.

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