A landmark pioneering project for a true circular economy
Given the ambitious climate goals across the EU, sustainability in the construction industry has long assumed a central role. Façade refurbishment in existing buildings in particular offers enormous potential. In a world first, a complete aluminium and glass façade has now been removed, recycled and reinstalled in a pilot project on metal construction company Lenderoth’s office and production building in Bremen. In the following interview, Christophe Lenderoth (Christophe Lenderoth GmbH), Marcel Bartsch (WICONA) and Moritz Feid (Saint-Gobain Glass) explain the background and how a true circular economy functions in practice.
What are the construction and metal construction industries doing for sustainability right now?
Moritz Feid: The subject of sustainability is really becoming more important in the construction industry. There is a greater demand than ever for sustainable products. In addition, the market is making more specific demands on the recyclability of the products already installed. In terms of glass, this means that glazing needs to be removed from existing buildings, and then recycled and reused in new buildings as a part of the circular economy. Sustainability was a nice "add-on" for a long time, but things are now developing to the point where certain requirements are becoming standards across the industry.
Christophe Lenderoth: I would like to add to this. While things are moving in the right direction, there is still not nearly enough done for sustainability. The Circularity Gap Report was presented at the World Economic Forum in Davos. This report states that, in the entire economic cycle, the functioning circular economy only amounts to 7.2%. This means that 93% is merely a linear economy – there is massive potential here for conserving resources. And this is where we are now taking action.
Marcel Bartsch: We are starting to see that sustainability is playing an increasingly important part in the decision process, particularly with investors and property developers. But the pressure to build sustainably for many key influencers is still not high enough. But it will definitely come – not least in view of EU taxonomy. The current market situation with its steep decline in new-build business, offers a great opportunity to focus even more on revitalisation and renovation, and to advance the circular economy in terms of conserving resources and saving CO2.
So, to be more specific, how important is sustainability to Lenderoth, Saint-Gobain Glass and Wicona?
Christophe Lenderoth: For us as a metal construction company, sustainability is hugely important, and we aim to have a pioneering role in this. This applies not only to our internal operations, but above all to our projects. We offer our clients window and façade solutions – either directly or as an alternative – that have the lowest possible CO2 emissions. We take a global approach to this, and not only build energy-efficient façades but also focus on using materials that have been produced with the lowest possible CO2 emissions. The idea of the circular economy is key to this. So, this is how we began the process to collaborate with WICONA and Saint-Gobain, to undertake this unique revitalisation of our own building façade.
Marcel Bartsch: Everyone at WICONA knows that sustainability is extremely important, and our parent group Hydro has always been a pioneer in this area. Our sustainable aluminium alloy Hydro CIRCAL 75R has now been available for five years in the market. And, since 2023, we have a new alloy Hydro CIRCAL 100R. This is made from 100% end-of-life aluminium and, with an average of 0.5 kg CO2 per kg aluminium, has the lowest CO2 footprint available globally in the industry.
Moritz Feid: The topic of sustainability is also at the centre of the business of Saint-Gobain Glass. In discussions on the important areas for action over the coming years, a key topic is the plan to become a pioneer in sustainable construction. As a large building materials manufacturer, we can of course use the synergies of our individual brands. In other words, we have Saint-Gobain Glass, we have Isover, Rigips, Weber, and so on. And each of these brands has already developed sustainable solutions –at Saint-Gobain Glass we have introduced ORAÉ, the first low CO2 glass on the market. For the glazing sector, this offers a CO2 footprint of only 6.64 kg CO2 equivalents per m² (with a 4 mm glass thickness). If we can now manage to link these individual brands to work alongside each other, we will have an integrated approach which will really enable the raw and end-of-life materials to be recirculated and recycled more effectively. And that is why this is an extremely interesting project with Lenderoth.
Our aim was to build a façade with the minimum consumption of resources and a maximum saving of CO2 emissions – this is what we see as holistic sustainability
Christophe Lenderoth
How did the concept arise to recycle the whole façade of Lenderoth's office and production building?
Christophe Lenderoth: Here at our Bremen location, we have a façade that was constructed in the 1970s. This, of course, no longer meets today's requirements in terms of thermal protection and heat insulation. In view of the sharp increase in energy prices, we wanted to act as quickly as possible and carry out a renovation on our building. So, we decided to implement a modern glass and aluminium façade with minimal resource consumption and maximum possible CO2 savings. It was soon clear to us that we needed to think of sustainability holistically, and not forget about the disposal of the existing façade in terms of a circular economy. In WICONA and Saint-Gobain Glass we have found truly great partners for this ambitious project.
What is special about this project and what was the building process?
Marcel Bartsch: For us, this project is a world première and a showcase project for a true circular economy. With Hydro CIRCAL 100R, we had the opportunity of putting an aluminium alloy into our tried and tested WICTEC 50 stick façade that consists entirely of end-of-life material. This means we get new products from old. The old aluminium components were removed, sorted and processed in our recycling plant in Dormagen using our patented recycling process. They were then turned into new profiles, which were reinstalled here at Lenderoth – a true circular economy without any new primary aluminium.
Moritz Feid: The same applies to the glazing. The interesting thing about this façade here – and this is an example applying the circular economy – is that the old glass was dismounted and collected, broken into pieces, then melted in the float plant and finally processed into new insulated glass – all on site. And these insulating glass units made with our ORAÉ glass were finally installed here in the façade. This demonstrates the successful cooperation between the recycling and sales departments, in order to serve both facets of the construction project – dismantling and new glazing.
Christophe Lenderoth: Precisely. With the façade, we wanted to branch out, think out of the box and, obviously, inspire others to act more sustainably. The façade presents a flagship project in Northern Germany right now. Working with WICONA and Saint-Gobain Glass, we have been able to implement our façade renovation entirely from secondary raw materials, thus saving a total of 24.6 tonnes of CO2.
We already have the technology for producing new profiles of 100% end-of-life aluminium in the same top quality
Marcel Bartsch
Is this different from a traditional metal construction project in terms of the building or the processes?
Christophe Lenderoth: The process is identical to any other façade renovation. We only have to pay a bit more attention when dismantling the façade to ensure that the materials are separated and carefully sorted. To allow for this, we provided two different containers for glass and aluminium. This means that the deconstruction process must be planned so that the materials can be removed to the relevant recycling plant of Hydro or Saint-Gobain Glass.
Marcel Bartsch: If I may add to that: in general, with urban mining in mind, we need to think about the future with our projects now, and plan for the dismantling of the existing resources in around 30-50 years. Products need to be designed sustainably and with circularity in mind in order to simplify sorting and material separation when they reach the end of their lifecycle. This is essential for them to be reused and remain in the cycle.
And finally, a look ahead. What do you think: will recyclable façades become a building standard?
Moritz Feid: Yes, certainly. We are talking about a transformation of the sector. And the construction industry is a large sector. The building and construction industry produces a lot of CO2 emissions. And we cannot ignore this. I would even assume that, over the next few years – say by 2030 at the latest – we will be subject to stricter statutory regulations. And we will then be forced to systematically reclaim raw materials, reprocess them and reinstall them. This is why Saint-Gobain is developing its own department for recycling end-of-life products.
Christophe Lenderoth: A good point. When it comes to regulations, I am keen that government will quickly ensure more commitment and security. The guidelines still lack clarity. But to return to your question. Yes, a recyclable façade will become standard, because the circular economy is the key to controlling global resource consumption. From that point of view, we have no other choice.
Marcel Bartsch: True. In the long-term we cannot simply carry on building with primary raw materials. We need to decide right now to put all our energy into further establishing the circular economy in façade construction. We have the necessary technology and need to start using them. And this will only work in cooperation with strong industry partners like Saint-Gobain and metal construction companies like Lenderoth.
The topic of urban mining is a reality. Nowadays the raw materials are to be found in the cities and need to be mined there