Commissioned in 1989 and completed in 1991, the Delftse Poort complex in Rotterdam was once the pride and emblem of Nationale-Nederlanden, one of the largest insurance and asset management companies in the Netherlands. Depending on the weather, the gridded glass tower shimmered bright blues or dark greys. On the one hand a typical 90s mirrored office building and on the other an icon of the Rotterdam skyline.
Until 2009, Delftse Poort was the tallest building in the Netherlands and for a decade hosted the Dutch run-up contest, it took the athletes 745 acidifying steps to reach the top. The building also served as a canvas for sponsorship campaigns, including a gigantic photo of soccer legend Edgar Davids, seemingly rushing out of the building’s facade in 2010.
Until 2009, Delftse Poort was the tallest building in the Netherlands and for a decade hosted the Dutch run-up contest, it took the athletes 745 acidifying steps to reach the top. The building also served as a canvas for sponsorship campaigns, including a gigantic photo of soccer legend Edgar Davids, seemingly rushing out of the building’s facade in 2010.
The whole complex comprises 106,000 square meters and is composed of three staggered planes connected by a three-story high plinth, thoughtfully combined by Dutch architect Abe Bonnema. Following a restructuring of the building’s ownership in 2005, Nationale- Nederlanden reduced its footprint within the building and began sharing with parent company ING. By 2015, Nationale-Nederlanden was no longer the building’s main tenant, resulting in the removal of the large orange logo that adorned the North Tower all those years. The building was bought by real estate magnate CBRE in 2009, and is now leased to several tenants, with Nationale-Nederlanden occupying 18,000 of the available 66,000 square meters of office space. This has not stopped them from investing in an ambitious ‘circular’ interior design for both the Delftse Poort and Haagse Poort, their head office in The Hague.
The shell and core of an office building can retain its value for decades or longer while the interior – within our current linear economy – loses its value the moment it is put into use. Office interiors are subject to an endless replacement of partition walls, flooring, fixtures, and furniture long before they are worn out. The vast majority of the material is not reused elsewhere but ends up being ‘recycled’ (which for the most part means incinerated in waste-to-energy plants) or in landfill. Nationale-Nederlanden opted to radically break with this habit for its Rotterdam refurbishment, aiming for the highest sustainability ambitions of a 100% circular design and Zero Waste.
This is easier said than done. It means making a painstaking inventory of every object and material in the office and finding a place for it in the new interior design or, where this is not feasible, a new destination has to be found elsewhere. What makes the Delftse Poort project remarkable is not the good intentions – green, sustainable, circular – which are widespread across the Netherlands by now, but the persistence of the client and architect in actually following the Zero Waste principle to the letter.
They also committed to scrupulously tracking their environmental impact in numbers. While architecture is increasingly subject to sustainable building standards laid down in building decrees and certificates, this has not been the case so much for interior design. The smaller size, shorter timelines, and lower budgets may explain the absence of credible certificates and systems for interior design. This limits the potential deeper analysis of ‘impact’ and leads to environmental strategies that are dependant largely on the designer’s intuition and the client’s appetite for greenwashing. In terms of size, interior re-fits are responsible for a considerable share of building waste because of the easy disposability of the material.
Speaking to different stakeholders involved in the renovation – the architects, client, consultants, and producers – reveals what is actually required of all parties in order to make their share of the work measurable. The starting point was the situation as it was, with everything already ‘in there’ as opposed to a (fictional) empty floor. From there the engineering firm LBP|SIGHT created, as a point of reference, an assessment framework by calculating the environmental impact of a regular project in which the old interior is discarded and replaced by a completely new interior. This assessment was paired up with definitions for waste leading to the decision to take “recycling to an equal raw material value” as the zero line. Re-use scored positively while incineration with energy recovery had the lowest negative score. It was not permitted to take anything to a landfill. By placing a great emphasis on reuse, but also through additional solutions such as packaging-free deliveries and the use of electric transport, a 70 percent environmental impact reduction could be achieved.1
In 2019, Delft-based Architects Fokkema & Partners were charged with this mission.Typically, they have to convince clients to take a more sustainable approach; with Nationale-Nederlanden it was the common shared starting point. Twan Steeghs, associate partner, and Dirk Zwaan, senior architect talked us through what it took to realize Zero Waste.
Speaking to different stakeholders involved in the renovation – the architects, client, consultants, and producers – reveals what is actually required of all parties in order to make their share of the work measurable. The starting point was the situation as it was, with everything already ‘in there’ as opposed to a (fictional) empty floor. From there the engineering firm LBP|SIGHT created, as a point of reference, an assessment framework by calculating the environmental impact of a regular project in which the old interior is discarded and replaced by a completely new interior. This assessment was paired up with definitions for waste leading to the decision to take “recycling to an equal raw material value” as the zero line. Re-use scored positively while incineration with energy recovery had the lowest negative score. It was not permitted to take anything to a landfill. By placing a great emphasis on reuse, but also through additional solutions such as packaging-free deliveries and the use of electric transport, a 70 percent environmental impact reduction could be achieved.1
In 2019, Delft-based Architects Fokkema & Partners were charged with this mission.Typically, they have to convince clients to take a more sustainable approach; with Nationale-Nederlanden it was the common shared starting point. Twan Steeghs, associate partner, and Dirk Zwaan, senior architect talked us through what it took to realize Zero Waste.
Marieke van den Heuvel [MvdH]: Can you describe the background of your practice and the inception of the National Nederlanden project?
Twan Steeghs [TS]: Following the financial crisis in 2008, many new construction projects were put on hold or got cancelled. Renovation and transformation of existing buildings therefore became an even greater part of our portfolio. Reuse plays a major part in this. There are currently millions of square meters of empty offices, even in prime locations, across the Netherlands. Due to new regulations2, these buildings must be upgraded, which makes renovation an interesting exercise: to give the space a new life but not to throw away too much in the process. This is a particular challenge for interiors because they have a much shorter lifespan than a building. There is an entrenched culture of just tossing things out and producing waste. It’s incredibly difficult to bring discarded materials back into the supply chain for building contractors because by definition they do not have intrinsic value – let alone added value – for a client. With Nationale-Nederlanden, the client was the initiator of sustainability, putting a full Zero Waste ambition on the table. It went as far as thinking about what to do with the discarded cigarette butts.
Twan Steeghs [TS]: Following the financial crisis in 2008, many new construction projects were put on hold or got cancelled. Renovation and transformation of existing buildings therefore became an even greater part of our portfolio. Reuse plays a major part in this. There are currently millions of square meters of empty offices, even in prime locations, across the Netherlands. Due to new regulations2, these buildings must be upgraded, which makes renovation an interesting exercise: to give the space a new life but not to throw away too much in the process. This is a particular challenge for interiors because they have a much shorter lifespan than a building. There is an entrenched culture of just tossing things out and producing waste. It’s incredibly difficult to bring discarded materials back into the supply chain for building contractors because by definition they do not have intrinsic value – let alone added value – for a client. With Nationale-Nederlanden, the client was the initiator of sustainability, putting a full Zero Waste ambition on the table. It went as far as thinking about what to do with the discarded cigarette butts.
MvdH: Can you take me to the beginning of the project?
Dirk Zwaan [DZ]: We started in 2019, and the project was scheduled to be completed by the end of 2021. The design was executed in phases as they were still using parts of the building. The COVID-19 pandemic impacted our assignment: Nationale-Nederlanden divested several floors in the building and decided that more people will be sharing the office as most of the staff were only coming in part-time. Fortunately, our design already responded to hybrid and flexible work models, and we only had to make minor adjustments, in that regard the design was tuned into the zeitgeist quite well.
Dirk Zwaan [DZ]: We started in 2019, and the project was scheduled to be completed by the end of 2021. The design was executed in phases as they were still using parts of the building. The COVID-19 pandemic impacted our assignment: Nationale-Nederlanden divested several floors in the building and decided that more people will be sharing the office as most of the staff were only coming in part-time. Fortunately, our design already responded to hybrid and flexible work models, and we only had to make minor adjustments, in that regard the design was tuned into the zeitgeist quite well.
MvdH: How did the conversation with Nationale-Nederlanden about their circular ambitions begin?
TS: The client’s goal was Zero Waste and a WELL certification.3 Together with a consultancy and engineering firm called LBP|SIGHT, who joined the team, we’ve set up a conceptual framework using the 10-Rs model4, with reuse as the main strategy, to reach those ambitions. LBP|SIGHT calculated all shadow costs5 to provide insight into the reduction of the environmental impact compared with a classic renovation. This led to the choice of local manufacturing and using electric transport where possible. Throughout the development, all parties in this project were obliged to indicate where their products originated, which drove them crazy. The LBP|SIGHT entered all this data into an enormous and complex Excel sheet. In the design itself, we limited the use of new materials. For every existing element, we tried to find a function in the new design or a repurposing somewhere else. We were committed to doing this while maintaining quality. Only when there really was no other solution did materials get grounded into asphalt for road construction. That’s the worst option, but at least nothing got burned.
TS: The client’s goal was Zero Waste and a WELL certification.3 Together with a consultancy and engineering firm called LBP|SIGHT, who joined the team, we’ve set up a conceptual framework using the 10-Rs model4, with reuse as the main strategy, to reach those ambitions. LBP|SIGHT calculated all shadow costs5 to provide insight into the reduction of the environmental impact compared with a classic renovation. This led to the choice of local manufacturing and using electric transport where possible. Throughout the development, all parties in this project were obliged to indicate where their products originated, which drove them crazy. The LBP|SIGHT entered all this data into an enormous and complex Excel sheet. In the design itself, we limited the use of new materials. For every existing element, we tried to find a function in the new design or a repurposing somewhere else. We were committed to doing this while maintaining quality. Only when there really was no other solution did materials get grounded into asphalt for road construction. That’s the worst option, but at least nothing got burned.
MvdH: Do you know how old the existing interior was when you started?
DZ: Partly. The interior contractor had been working with the client for a long time. They knew that some of the pantries over in Haagse Poort were only one or two years old. Part of the bespoke furniture used in the Delftse Poort had also only recently been installed. We looked at what we could do with every single element. We re-used the existing pantries, but with added paneling because it had previously stood against a wall. We also brought back all the seating booths, but with new upholstery. We made acoustic panels from the old fabric.
DZ: Partly. The interior contractor had been working with the client for a long time. They knew that some of the pantries over in Haagse Poort were only one or two years old. Part of the bespoke furniture used in the Delftse Poort had also only recently been installed. We looked at what we could do with every single element. We re-used the existing pantries, but with added paneling because it had previously stood against a wall. We also brought back all the seating booths, but with new upholstery. We made acoustic panels from the old fabric.
MvdH: How did the circular strategies of ‘harvesting’ and collaborating with the building parties early on influence your design process?
DZ: We started with a Preliminary Design as usual, although we didn’t know whether certain materials would be available for use. A big difference with other projects is that we didn’t make a Definitive Design, as is standard procedure in architecture; nor did we make a regular set of construction drawings, but rather we made a design manual. This manual described our vision, which we shared with the builders, and collaboratively we defined all materialization and details in workshops. For example, we showed visualizations of a pantry with a wooden finish and the contractors came with samples of ‘harvested’ wood. We also asked them to come up with alternatives for products such as ceramic tiles. One contractor proposed tiles made from construction waste and we ended up using that.
DZ: We started with a Preliminary Design as usual, although we didn’t know whether certain materials would be available for use. A big difference with other projects is that we didn’t make a Definitive Design, as is standard procedure in architecture; nor did we make a regular set of construction drawings, but rather we made a design manual. This manual described our vision, which we shared with the builders, and collaboratively we defined all materialization and details in workshops. For example, we showed visualizations of a pantry with a wooden finish and the contractors came with samples of ‘harvested’ wood. We also asked them to come up with alternatives for products such as ceramic tiles. One contractor proposed tiles made from construction waste and we ended up using that.
MvdH: Were you responsible for the complete inventory of the existing interior?
DZ: We had a real-time harvest map in which all collaborating parties such as the wall supplier, the interior builder, and the upholster kept track of their contribution. At the start, everything was divided into ‘plots’ that were assigned to the different parties, one encompassing all the carpets, one overseeing the partition walls, one for customized furniture, one for factory-made furniture, and so on. This way everyone knew what elements and materials were being used and what was available.
DZ: We had a real-time harvest map in which all collaborating parties such as the wall supplier, the interior builder, and the upholster kept track of their contribution. At the start, everything was divided into ‘plots’ that were assigned to the different parties, one encompassing all the carpets, one overseeing the partition walls, one for customized furniture, one for factory-made furniture, and so on. This way everyone knew what elements and materials were being used and what was available.
MvdH: You worked on two buildings at the same time – could you mix harvested materials from one site with the other?
DZ: Yes. There was a difference in ceiling heights, which made it harder to exchange the partition walls, though we managed it in the end. Shifting between the bespoke furniture was easier.
The idea was that all parties could use each other’s materials, so if the interior builder had wood left over, it was used by the wall builder and vice versa. It sounds simple but it is a big challenge to keep the harvest file up to date: something changes every day, materials disappear, and new materials are added. At a certain point, the contractor started demolition and an older wall made of plasterboard appeared behind a retention wall. Because we didn’t want any waste, we had to come up with a solution for that too.
DZ: Yes. There was a difference in ceiling heights, which made it harder to exchange the partition walls, though we managed it in the end. Shifting between the bespoke furniture was easier.
The idea was that all parties could use each other’s materials, so if the interior builder had wood left over, it was used by the wall builder and vice versa. It sounds simple but it is a big challenge to keep the harvest file up to date: something changes every day, materials disappear, and new materials are added. At a certain point, the contractor started demolition and an older wall made of plasterboard appeared behind a retention wall. Because we didn’t want any waste, we had to come up with a solution for that too.
MvdH: What was it like to work with so many used materials?
TS: A surprising experience was the carpet. Over time, many different types of carpets have been used in both Delftse Poort and Haagse Poort, all of varying quality. At first, I thought we would be re-using the newest carpets, but we ended up taking the oldest ones as they are fabricated in a way that the different materials cannot be separated anymore, making them impossible to recycle. However, they were easy to clean and very durable. The newer carpets have an eco-backing which makes them better suited to disassembly, so they were taken back by the manufacturer.
TS: A surprising experience was the carpet. Over time, many different types of carpets have been used in both Delftse Poort and Haagse Poort, all of varying quality. At first, I thought we would be re-using the newest carpets, but we ended up taking the oldest ones as they are fabricated in a way that the different materials cannot be separated anymore, making them impossible to recycle. However, they were easy to clean and very durable. The newer carpets have an eco-backing which makes them better suited to disassembly, so they were taken back by the manufacturer.
DZ: Then we were stuck with all the old bright green and orange carpets, a color palette that we would never have come up with. This meant we had to adapt our design mindset. There was no alternative, other than grinding them into asphalt. Then we looked each other in the eyes and said “OK, we’re going to re-use it.” The actua refitting of the carpets was not easy either. When we asked the upholsterer to harvest, clean and reinstall the old carpets they were not appreciative at all and initially rejected the task. We learned that it takes a lot of time and energy to get the implementing parties on board. You really need to get them involved in the concept first. If we force this new way of working on these parties without convincing them of the reasoning behind it, the chances are the materials will end up in a dumpster.
TS: For example, an upholsterer is used to delivering a perfect project, that’s the honor of their profession. When reusing the carpet tiles, colour differences arose, which they would normally not find acceptable. Also, some of the carpets were so damaged that they could no longer be cleaned. We chose to accentuate the colour differences by placing the carpets in a tone-on-tone checkerboard. It took several meetings to come up with a set of design rules for this, which finally convinced the upholsterer of the concept.
DZ: Initially, the upholsterer did a test where everything that could go wrong, went wrong: they broke tiles and bubbles were visible during installation due to the glue residues that were difficult to remove. The first estimate of what could be reused was only a small percentage, but eventually they got better at the new process, and it worked out well in the end.
There’s a lot of labor involved when reusing the carpet tiles. Is it realistic to do this in other projects, when you compare the labor costs to the price of new tiles?
TS: Good question. In a reuse project, there is a big shift from material costs to labour costs. I think we got lucky with this client and the budget was available to accommodate this shift. As far as Nationale-Nederlanden were concerned, this project was a business card, an exemplary project that they want to roll out as a standard for all of their offices.
TS: Good question. In a reuse project, there is a big shift from material costs to labour costs. I think we got lucky with this client and the budget was available to accommodate this shift. As far as Nationale-Nederlanden were concerned, this project was a business card, an exemplary project that they want to roll out as a standard for all of their offices.
Is it more expensive to set up a project in a circular way than when you opt for more conventional solutions?
DZ: I don’t have the most recent insight into the costs but it’s definitely not cheaper. But we’re also doing a few floors in the so-called “post-COVID-19 areas” where we focus on hybrid working with innovative and biobased materials such as fruit leather, chairs made with industrial hemp fibres, or a composite made of rice husks. These materials are exciting to work with but sometimes expensive and more difficult to use as some are still under development. This means they are only available in small quantities and their Life Cycle Analysis (LCA) has not been fully calculated. This was an extra complication because we were considering only materials with the lowest possible Environmental Cost Indicator (ECI). We decided to include these new materials because we believed that by using them, we were investing in the suppliers, hopefully leading to more interesting developments in the future.
DZ: I don’t have the most recent insight into the costs but it’s definitely not cheaper. But we’re also doing a few floors in the so-called “post-COVID-19 areas” where we focus on hybrid working with innovative and biobased materials such as fruit leather, chairs made with industrial hemp fibres, or a composite made of rice husks. These materials are exciting to work with but sometimes expensive and more difficult to use as some are still under development. This means they are only available in small quantities and their Life Cycle Analysis (LCA) has not been fully calculated. This was an extra complication because we were considering only materials with the lowest possible Environmental Cost Indicator (ECI). We decided to include these new materials because we believed that by using them, we were investing in the suppliers, hopefully leading to more interesting developments in the future.
Have you made any new, surprising discoveries?
DZ: Yes. Even though I have also worked on other sustainably-driven projects, this one feels like– for the first time – genuinely circular. But a lot of research needs to be done, everything is still in its infancy. Companies say they have the most fantastic sustainable products, but there is still a lot of greenwashing out there. If you dig a bit deeper or have parties like LBP|SIGHT do the calculations, then there is a lot of hot air, or just very good solutions but just focussed on one specific area. In a sense, we are all pioneers.
TS: Sustainable and circular building is inevitable and will happen more and more. There is increased awareness with clients, who have stronger demand and I’m sure most designers are interested. It’s the contractors that need to come on board.
DZ: Yes. Even though I have also worked on other sustainably-driven projects, this one feels like– for the first time – genuinely circular. But a lot of research needs to be done, everything is still in its infancy. Companies say they have the most fantastic sustainable products, but there is still a lot of greenwashing out there. If you dig a bit deeper or have parties like LBP|SIGHT do the calculations, then there is a lot of hot air, or just very good solutions but just focussed on one specific area. In a sense, we are all pioneers.
TS: Sustainable and circular building is inevitable and will happen more and more. There is increased awareness with clients, who have stronger demand and I’m sure most designers are interested. It’s the contractors that need to come on board.
Another important circular strategy is that everything should be built for disassembly. Is that the case at Nationale-Nederlanden?
DZ: Yes, everything is screwed or made with a type of loose connection. Being transparent about how something is assembled creates a different aesthetic. But we still wanted to create seamless connections in the design. To achieve this, we used French cleat hangers. It remains a corporate environment and it cannot look homemade. The client accepted a lot of compromise, but there are limits to that.
DZ: Yes, everything is screwed or made with a type of loose connection. Being transparent about how something is assembled creates a different aesthetic. But we still wanted to create seamless connections in the design. To achieve this, we used French cleat hangers. It remains a corporate environment and it cannot look homemade. The client accepted a lot of compromise, but there are limits to that.
In which areas of the project did you gain the best results?
DZ: If you look at the diagram made by LBP|SIGHT you can see how the Nationale-Nederlanden project scores compared to a conventional office design: all categories considered, we achieved 70 percent less impact than a conventional office refit. It was difficult to make a bigger improvement on a construction level because of the nature of the project, which was focused on the interior without large constructional interventions. The difference we made with individual pieces of furniture was significant. The challenge here was that we often could not trace the product specifications, so we had to find out by experiment if they would meet the current requirements. To do this, we created a specific room in which we put all the harvested furniture to assess whether it still contained any harmful substances.
DZ: If you look at the diagram made by LBP|SIGHT you can see how the Nationale-Nederlanden project scores compared to a conventional office design: all categories considered, we achieved 70 percent less impact than a conventional office refit. It was difficult to make a bigger improvement on a construction level because of the nature of the project, which was focused on the interior without large constructional interventions. The difference we made with individual pieces of furniture was significant. The challenge here was that we often could not trace the product specifications, so we had to find out by experiment if they would meet the current requirements. To do this, we created a specific room in which we put all the harvested furniture to assess whether it still contained any harmful substances.
The client has already mentioned that they will continue changing the interiors. How do you ensure that this interior can be re-used again in the future?
TS: First, we have the harvest map we used during the development of the interior in which everything we used in the building is described and calculated. Additionally, Nationale-Nederlanden was considering the possibility of making agreements with other parties – the interior builder, the wall supplier, and so on – to maintain, repair, or take back products at the end of the office’s lifespan. That is why it is so important to build demountable. That could not be done for the elements that belong to the building owner, such as the ceilings. But in the future, when the project is delivered to facility services, things will unavoidably shift or break. As designers, you pass on the baton, while the project ambitions require continued attention. Especially in this case – inherent to the concept of circularity – it never stops.
TS: First, we have the harvest map we used during the development of the interior in which everything we used in the building is described and calculated. Additionally, Nationale-Nederlanden was considering the possibility of making agreements with other parties – the interior builder, the wall supplier, and so on – to maintain, repair, or take back products at the end of the office’s lifespan. That is why it is so important to build demountable. That could not be done for the elements that belong to the building owner, such as the ceilings. But in the future, when the project is delivered to facility services, things will unavoidably shift or break. As designers, you pass on the baton, while the project ambitions require continued attention. Especially in this case – inherent to the concept of circularity – it never stops.