Four Circular Buildings Pathways Towards 2050

Metabolic: Ivan Thung, Nico Schouten, Job Papineau Salm, Harmen Heida, Reinout Haisma, Toni Kuhlman.
Graphic design: Anna Mishchenko, Cassie Björck

The challenge of emissions, material consumption and waste in the construction sector.

The construction sector in the EU is a major carbon emitter, with an estimated 190 Mt CO2e emitted in 2024 for new construction, and an expected average annual emission of 245 Mt CO2e between 2024 and 2050. The sector also generates huge amounts of waste: we estimated in 2022 that the demolition flow generated 124 Mt that year.  As we continue to build (adding 22 billion m2 of floor area
until 2050 under a business-as-usual scenario), the sector is expected to emit an additional 6.6 Gt CO2e, or the equivalent of about ten times the annual emissions of Germany in 2022. Continuing to build in our old ways is unsustainable; it will push the residential and utility construction sector in Europe past the 1.5°C warming limit in 2026, and past even the 2°C mark by 2031. However, we can radically reduce environmental damage and unlock new value by applying circular economy principles to the built environment.

A circular building scenario combined with decarbonisation has the potential to reduce the construction sector’s CO2 e emissions by 4.15 Gt and keep the 2 ̊C global warming scenario within reach.

We estimate that the remaining CO2e budget in 2024 for the construction sector of the European Union countries plus the UK (EU27+UK) to limit warming to 1.5 ̊C and 2.0 ̊C is 0.51 Gt and 1.97 Gt, respectively (further details on the carbon budget of EU27+UK’s construction sector are provided in the Technical Annex D). We have modelled the effects on carbon emissions and material consumption of implementing a ‘Circular Building Scenario’ – a set of four pathways, implemented through nine interventions based on circular economic principles as outlined by Arup’s Circular Buildings Toolkit.4 By implementing nine circular interventions and projected decarbonisation activities, we will not remain within the 2.0 ̊C CO2e budget allocated to the built environment.
However, these interventions substantially mitigate the exceedance and keep the 2 ̊C scenario within reach for the sector. The adoption of the Circular Building Scenario alongside decarbonising the industry will postpone the exceedance of the EU27+UK construction sector’s 2-degree CO2e budget by nine years, shifting exceedance from 2033 to 2042.

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