On Wednesday 4 November, at the Klimaattop Gebouwde Omgeving (the Dutch climate summit for the built environment) in the Jaarbeurs in Utrecht, Sacha Brons was named number one of the Duurzame 50 of 2026. Sacha leads Climate Cleanup's work on Construction Stored Carbon. From 187 nominations, the jury chose fifty people who are making the built environment sustainable. Sacha tops the list.
From number ten to number one
In 2024 Sacha was number ten of the Duurzame 50 and won the Young Professional Award. In 2025 he sat on the jury himself. Now he is number one. The Duurzame 50 looks at initiative and the power to deliver, impact, sharing knowledge and inspiring others, and the contribution to changing the system.
When he won in 2024, he put a question to the sector that still stands:
Do you know how much CO2 is stored in your property portfolio?
Next to our footprint, he asked us to count our handprint: "Doing less harm is crucial, but isn't more repair just as important?"
A building can be a carbon bank
What is recognised today is bigger than one career. It is an idea that stood at the edge for years: building can repair the climate. Trees and crops take CO2 out of the air. As wood, straw, hemp or flax, a building holds that carbon for decades to centuries. Build with what grows, and the city becomes a carbon bank, and the field and the forest become suppliers of the building site.
In 2021 Climate Cleanup and ASN Bank published a method to count carbon storage per building, as far as we know the first in the world. In 2022 the Dutch House of Representatives adopted, with 121 votes, a motion that used our term Construction Stored Carbon. Since 2022 Sacha has carried the work forward with dozens of frontrunners: a certification protocol following the EU's CRCF, an open calculation tool, the first certified projects through Oncra, and in January 2026 the Dutch quantification method for material-bound CO2 storage.
It is already happening
- The open Oncra register lists 24 construction projects, from EDGE Coolsingel in Rotterdam to the town hall of Krimpenerwaard, together more than 41,000 tonnes of CO2 in pre-validated storage.
- The Dutch state is buying. For the Ministry of Agriculture, Fisheries, Food Security and Nature, the Nationaal Groenfonds buys certificates for carbon stored in biobased building materials, under the SNK method or the Oncra protocol.
- In Brussels the European Commission and its Expert Group on Carbon Removals are preparing the EU method for carbon storage in building products, with Sacha as strategist.
Now the rules
From 2028 the CO2 of every new building over 1,000 m² must be calculated over its whole life, the WLC-GWP, and from 2030 that of every new building. From 2030 limit values apply too. How stored carbon counts in that calculation has not been decided yet.
Recognition on stage is wonderful. Recognition in the rules is what counts.
Congratulations, Sacha. Onwards!
Sources: KTGO, Duurzame 50 2026; Oncra register, construction projects (4 November 2026); Nationaal Groenfonds, tender for carbon certificates from biobased building materials; Stichting NMD, roadmap WLC-GWP; Climate Cleanup, Construction Stored Carbon.