Circular construction is the future

This week is the Week of the Circular Economy. A great time to showcase the first 100% circular wooden window frames with circularly manufactured HR++ glass and fully circular solid doors. This is happening in Bos en Lommer, where these circular products have been applied for the first time in the complex 'De Bosleeuw' of housing corporation Stadgenoot. 

How it began

It began in 2019 with a competition by the City of Amsterdam: "Towards a Circular City. The competition aimed to develop practical experience and knowledge about circular construction in the transition to a circular and natural gas-free housing stock for Amsterdam. Hemubo came up with a concrete solution to reduce some of the main waste streams from renovation projects: glass and window frame materials. We asked ourselves how we could repurpose scrap wood and double-glazing in a circular and cost-efficient way. We won the competition.

Now, three years later, together with Stadgenoot, Timmerfabriek De Jong Woudsend, GSF Glasgroep, Kegro and the municipality of Amsterdam, the first fully circular frames, glass, windows and doors have been installed in a project.


Thieme Hennis, in collaboration with the C-Creators foundation, devised the competition for the City of Amsterdam, supplemented by an inspiring circular program that also supported the corporations in terms of content. He is incredibly enthusiastic about the final realization of what was once a concept and the substantial climate gains that can be achieved. Thieme: "The best thing about this project is that it involves a chain-oriented approach. This has led to special collaborations and structural changes in production processes. All partners are here and they all want to go the extra mile to start building circularly. To be a part of it. That's what we want. Thanks to available grants and funding opportunities, we can encourage this even more in the coming years, so I'm looking forward to the follow-up. If all parties join hands, a lot is possible."

Director Egbert Dekker of Stadgenoot: "We want our tenants to also be allowed to live in a world that is pleasant in the longer term. That means we have to invest now. We want to go the extra mile in this and take the initiative. That may cost some extra money now, but in the long run it will come back to us. Especially if we can deploy these kinds of circular solutions on a larger scale. It suits us as Stadgenoot housing corporation to make this social task possible. And in this we like to work together with innovative partners."

Building a circular future together

Director Ferdi de Jong of Timmerfabriek De Jong Woudsend is one of the partners: "We received the harvest, the wood from another renovation project of Stadgenoot (Osdorpplein), roughly sawn and delivered nail-free. Sometimes the wood has then already made an intermediate stop at another party to be preserved. At our factory we repair cracks and errors, after which we cut the frames to the correct length, width and thickness. Then we assemble the frames in the complex. The DNA of the window frame can be traced via an NFC chip. If you scan it with your phone, you will find information about, for example, the hardware, paint and glass. Circular solutions are the future. And if we join forces, this can also be taken up on a larger scale in the future."

Maarten Rood, director of GSF Glasgroep, agrees: "To make glass, you obviously need raw materials and we want to avoid tapping new raw materials as much as possible. Moreover, you emit a gigantic amount of CO2 to melt these raw materials into glass. We are, until now, the only one in the Netherlands that also offers circular glass. We harvest glass from various renovation projects. That glass is cleaned and assessed for quality. Usually about 80% is suitable for reuse.

The HvA and TU Delft are currently investigating the possibilities of reusing circular glass for a third, fourth or even fifth life cycle. I see the future in this product anyway. We want to be a forerunner in this. If scaling up succeeds, it will automatically become cheaper. Hemubo's recent investment in GSF Glasgroep helps us in this respect. This will enable us to continue working together in the coming years to develop, refine and scale up the production of circular glass.

Bert Steenvoorden, senior account manager of Kegro Deuren, was approached by Hemubo and De Jong Woudsend to supply the doors, also made of circular wood, of course. Bert: "We harvest wood from returned doors from both larger renovation projects and private individuals. The wood from these doors is reprocessed into components from which new hardwood doors are made. We also used those in this project. We simply cannot continue to throw everything away and deplete the earth. So when we do it then, we do it right. Instead of a "traditional door" of 38 mm, we installed here a 54 mm door with a higher insulation value. We think it is important to contribute to a sustainable future. This is best done by entering into sustainable collaborations with partners who share the same philosophy. We are proud of this collaboration and the result is promising for a circular future!"

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