The construction industry must build less, use more sustainable materials and ‘clean up” traditional materials to meet climate commitments.
The findings come from a major report published by the UN Environment Programme and the Yale Centre for Ecosystems and Architecture, calling for a circular” approach to building materials.
With a focus on ‘Avoid, Shift and Improve,’ the report calls on policymakers, manufacturers, architects, developers, engineers, builders and recyclers to address the billowing emissions from construction activity.
Drawing on examples in Canada, Finland, Ghana, Guatemala, India, Peru, and Senegal, it is now calling on the global community to act, pushing for global cities to take a leadership role in the push to net zero.
Replacing Steel and Concrete with Timber will save 40% of emissions
It reports that substituting carbon-intensive building materials, like steel and concrete, for bio-based materials like timber, bamboo, and biomass will save emissions by up to 40% by 2050.
“However, more policy and financial support is needed to ensure the widespread adoption of renewable bio-based building materials.”
Building less and repurposing existing structures, which it has termed ‘the circular approach,’ will generate 50-75% fewer emissions than new construction.
This approach, which includes retrofitting, “is the most valuable option,” as it “promotes construction with fewer materials and materials with a lower carbon footprint and facilitating reuse or recycle.”
Concrete, Steel and Aluminium are responsible for 23% of emissions
It has also raised concerns about processing concrete, steel, and aluminium, “three sectors responsible for 23% of the overall global emissions.”
“Priorities should be placed on electrifying production with renewable energy sources, increasing the use of reused and recycled materials, and scaling innovative technologies,” the report said.
In addition, “transformation of regional markets and building cultures through building codes, certification, labelling and education is critical.”
According to Sheila Aggarwal-Khan, the director of the UNEP’s industry and economy division, the report highlights the need for global governments to do more to achieve net-zero targets.
Net Zero requires improved government policy and regulation settings
Net zero by 2050 is only achievable if “governments put in place the right policy, incentives and regulation to shift the industry action,” Ms Aggarwal-Khan said.
Rapid urbanisation means that every given day, the world adds buildings equivalent to the size of Paris, with the built environment responsible for 37% of global emissions. Driven by South Asia and Africa, the global economy is under increasing pressure to find construction materials.
According to the FAO and World Bank, demand for timber will quadruple over the next 30 years. New research produced by the World Resources Institute and published in Nature forecasts that timber harvesting will account for 10% of global emissions over the coming decades.
“Until recently, most buildings were constructed using locally sourced earth, stone, timber, and bamboo,” Ms Aggarwal-Khan said.
“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.”
Most climate action in the building sector focuses on reducing “operational carbon” emissions, including heating, cooling, and lighting.
However, thanks to the growing decarbonisation of the electrical grid and the use of renewables, “these are set to decrease from 75% to 50% of the sector in coming decades.”
Ms Aggarwal-Khan has urged global governments to be more ambitious with policy settings and said, “Policies must support the development of new cooperative economic models across the building, forestry and agricultural industries.”
In doing this, the global economy can “galvanise a just transition towards circular, bio-based material economies.”
‘Embodied Carbon’ shift requires a whole lifecycle approach to materials
With the shift from “operational carbon” to “embodied carbon”, the report has stressed the importance of a whole lifecycle approach to building material supply chains.
“This involves harmonised measures across multiple sectors and at each stage of the building lifecycle—from extraction to processing, installation, use, and demolition,” the report said.
Government regulation and enforcement are vital across all building lifecycle phases – from extraction to end-of-use.
“This ensures transparency in labelling, effective international building codes, and certification schemes.”
Ms Aggarwal-Khan is now calling on cities to drive the push to decarbonisation.
“Many are already integrating vegetated surfaces, including green roofs, façades, and indoor wall assemblies to reduce urban carbon emissions and cool off buildings, increase urban biodiversity and more.”