Rapid urbanisation worldwide means every five days, the world adds buildings equivalent to the size of Paris, with the built environment sector already responsible for 37 per cent of global emissions. A report published by the UN Environment Programme (UNEP) and the Yale Center for Ecosystems + Architecture (Yale CEA), under the Global Alliance for Buildings and Construction (GlobalABC), offers solutions to decarbonize the buildings and construction sector and reduce the waste it generates.

The report, Building materials and the climate: Constructing a new future, offers policy makers, manufacturers, architects, developers, engineers, builders and recyclers a three-pronged solution to reduce “embodied carbon” emissions and the negative impacts on natural ecosystems from the production and deployment of building materials such as cement, steel, aluminium, timber, and biomass:

  • Avoid waste through a circular approach;
  • Shift to ethically and sustainably sourced renewable bio-based building materials, including timber, bamboo, and biomass; and
  • Improve decarbonisation of conventional materials that cannot be replaced. This mainly concerns the processing of concrete, steel, and aluminium – three sectors responsible for 23 per cent of overall global emissions today – as well as glass and bricks.

The three-pronged Avoid-Shift-Improve solution needs to be adopted throughout the building process to ensure emissions are slashed and human health and biodiverse ecosystems are protected. The solution also requires, in its implementation, sensitivity to local cultures and climates, including the common perception of concrete and steel as modern materials of choice.

“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,” said Sheila Aggarwal-Khan, Director of UNEP’s Industry and Economy Division.

“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,” she added.

To date, most climate action in the building sector has been dedicated to effectively reducing “operational carbon” emissions, which encompass heating, cooling, and lighting. Thanks to the growing worldwide decarbonisation of the electrical grid and the use renewable energies, these are set to decrease from 75 per cent to 50 per cent of the sector in coming decades.”

“Since the built environment sector is so complex, with interdependencies across actors, all hands on deck are required to decarbonise, and we can’t leave anyone behind. Policies must support the development of new cooperative economic models across the building, forestry and agricultural industries, in order to galvanise a just transition towards circular, bio-based material economies that can also work synergistically with the conventional material sectors,” according to lead author Anna Dyson, Founding Director of the Yale Center for Ecosystems and Architecture (Yale CEA).