Can the construction sector become climate-neutral?

According to a report by the United Nations Environment Programme (UNEP) and the Center for Ecosystems and Architecture (CEA) at Yale University in the US, this should be possible - and necessary - worldwide by 2060. But only if materials are saved. Building materials such as concrete and steel would have to be produced in a more climate-friendly way and more renewable raw materials would also have to be used.

Every day, so many new buildings are constructed worldwide that a city the size of Paris could be built every five days - according to the recently published report.

37 percent of CO2 emissions worldwide are attributable to the construction industry.

"Until recently, most buildings were constructed from locally sourced earth, stone, wood and bamboo. But modern materials such as concrete and steel often only give the illusion of durability, usually end up in landfills and contribute to the growing climate crisis," explained Sheila Aggarwal-Khan, Director of UNEP's Industry and Economics Division.

Timber, biomass and bamboo from sustainable sources would be possible biological raw materials.

Concrete, steel or glass should at least be produced in a more climate-friendly way.

Reuse

The trend should be away from new buildings and towards the use of existing structures. The idea goes so far as to suggest that the reuse or dismantling of buildings should be considered as soon as they are built.

What is the biggest chunk?

The production of concrete, steel and aluminum is responsible for almost a quarter (23 percent) of emissions.

Concrete consumption alone has increased tenfold in the last 65 years.

In order to achieve the goal of climate neutrality for concrete by 2060, the Portland cement most commonly used for production would have to be replaced - preferably with regionally available alternatives from agricultural by-products, forestry or industry.

CO2 avoidance

Until now, it has only been an issue once a building has been completed. The focus was on using and installing renewable energy sources and minimizing energy consumption. The industry is on the right track.

During construction activity, however, CO2 emissions rise to dizzying heights.

What could a solution look like?

"Our best hope for radical decarbonization," say the authors, is the use of biomaterials such as bamboo and wood, as well as agricultural by-products.

The use of building materials that store carbon dioxide themselves could even make buildings CO2-negative in the future - unimaginable, but mathematically possible if they save more CO2 during their construction than they emit.