Erik Stenberg - Recreate

March 1, 2023
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The success of the ReCreate project would not be possible without the expertise of people that stand behind it. Our second interviewee is Erik Stenberg – Work Package 1 leader and Swedish country cluster leader. Ivan Fratrić of the Croatia Green Building Council will be conducting the interview. Here is his story:

 

I: Hello Erik and thank you for doing this interview! For starters, can you introduce yourself a bit and describe your role in the project and your organization?

E: Of course. I’m an architect and an associate professor at KTH Royal Institute of Technology in Stockholm, Sweden and I have a history both as a practicing architect and a teacher I’ve been (for the last 20 years or so) working especially on housing from the post-war period in Sweden and I’ve specialized in prefabrication system in concrete which was used in mass housing during the period from 1965. – 1974. in Sweden which was called the Million program era and how we renovate and update those housing areas. I work a lot with issues concerning sustainability and also technology and history. In ReCreate, I’m the Swedish country cluster leader and I’m also the Work package 1 leader.

 

I: You’ve mentioned that you have experience with sustainability – can you maybe tell me more about what made you inclined to join the project?

E: There were a couple of major reasons. One of them was to work and collaborate with Satu Huuhka who is an amazing person and researcher so that was very enticing in itself because she’s such an authority on the subject in Finland and has strong connections to Sweden and these other countries. The other one is following the trajectory of my interests and seeing prefab housing from the post-war era from yet another angle and as something positive or in other words as a resource and not something expensive to upkeep and generally as something bad. This is another way to describe the incredible effort of the post-war era and to test it on a 1:1 scale. Basically, I want concrete to be seen as an asset and not a liability. In every sustainability discussion today, concrete is always looked at as a liability – it’s too expensive to make in terms of carbon footprint, it represents a period in history where we were mass-producing housing and we have several words in Sweden when you add concrete or grayness it immediately has negative connotations. This project provides a way to turn that around and see concrete as an asset, as something positive, especially by using high-quality concrete we made in the ’50s, 60’s, and 70’s, we can now also lower the carbon footprint of new construction through it.

Erik Stenberg

I: Moving toward the Swedish pilot and the project itself. Can you shed more light on how you collaborate with other partners in your country cluster?

E: Sure! There aren’t many of us in the Swedish country cluster. There’s Helsingborgshem – a municipal housing company and Strängbetong – a material producer of concrete and KTH. The situation is a little different here in Sweden with regard to the pilot building. Helsingborgshem already has a long-term project on rejuvenating a housing area called Drottninghög, which is a typical post-war massive housing area with 1100 units of housing that are very similar and all built within the same 5-year time span. Now, that area has a weak socio-economical development and they have engaged in a long process of dialogues, they have changed zoning and are even producing new housing. The goal is to increase the number of housing from 1100 to 2600 units by 2030. To do this, they are tearing down some of the original housing which is prefabricated. When I approached them I said to them not to just crush the concrete, but to join the ReCreate project and see how we can actually reuse the concrete – both to provide a better history and a new story on the panels so they are not seen as something bad, but as something good and we also test new ways of sustainable construction. They agreed to this and have actually had a city-wide movement to have a city expo. It was in the spring of 2022. We had a very short time to do a physical pilot in the Swedish country cluster, but with the help of Strangebetong, we managed to build a small physical pilot as an exhibition pavilion for the H22 Expo. We tested the whole process in a physical pilot so we can make a digital pilot which is more precise and better but aimed at the future development of Helsingborgshem’s Drottninghög housing. This is the opposite of some of the other country clusters because we’re first working on a digital pilot to then prepare a larger, physical one.

 

I: That being said, one can presume that there were no issues with getting everyone on board for the project and that they were quite motivated to join the project and were sold on the idea of it.

E: They were. But again, it’s important to stress that we (the Swedish country cluster) consist of a few members. Part of it can be attributed to the fact that we have the municipal housing company as one member and they have to follow the rules of procurement so we could not have other partners join the team before we went through the process of public procurement so as we build the physical pilot and went through all of those stages we also engaged the construction company and other architects and engineers.

 

I: Returning to you – do you have some kind of internal motivation for the project? Something that intrinsically motivates you?

E: Of course! I’ve touched upon it earlier and I can say that it’s definitely the high regard for post war housing in Sweden, a subject I have been working on for the last 25 years. That is a very strong driver for me. The other driver is sustainability in the construction sector. As architects, we have to become much more knowledgeable about what the climate impact of what we’re designing. I think that’s where reusing really opens up an avenue where it’s not just about the regard for historic buildings but also how we produce new buildings with a lower climate impact and also a great architectural design.

Erik Stenberg

I: On a broader scale, can you describe why the ReCreate project is important from your perspective and what you see as its ultimate goal?

E: The project is important because it aims to reduce both the carbon footprint and the waste of the construction sector. These are two huge that we have. As a goal – I think if we can provide the tools, methods, and examples to cover some of the value chains, then we will have come a long way in the four years of the project.

 

I: That’s something that I also want to touch upon a bit further. So the project will last for four years and will officially end sometime in 2025. How do you see its progression after its official conclusion? What do you see as some of the hindrances of its uptake and what are some of the challenges it will be facing once it is over?

I think the business sector will move very quickly with many of these new findings and with the findings other projects are making. In a few years, I think there will be a few business models in action which will continue after ReCreate. I hope to see that there will be more pilots after the project. Those are some of the short-term effects. In the case of long-term effects – I hope we’re also starting to set in motion the way we educate architects and engineers to deal with existing buildings, the way we value the existing building environment in planning processes, the way that we set up future research projects to include reuse in the existing environment. Those are outputs that are just as important, but we won’t see them immediately. Redoing education for architects for instance can take decades. Those are the things that we contribute to ReCreate, but are not yet tangible as of this moment.

 

I: The process will definitely take time. This will also be a more personal question in that regard – do you think that we have the time for such a steady transition while also having the pressure of encroaching negative effects of climate change? Basically, what I’m asking is whether you have a positive or negative outlook on our chances of succeeding in ”saving ourselves” from climate change.

E: Well I’m very positive that we won’t meet the 1.5-degree goal by 2030. But I have a very positive outlook with regard to the engineering and architecture sector. I think the construction sector is in for a major change but we have faced these challenges before. Maybe not on the same scale and with the same level of threat, but I still think we will be moving ahead with that change even though we won’t meet the climatic goals and we won’t reduce the waste at the EU level fast enough. We won’t solve the problem in four years, but that is something that we need to do for the construction and demolition sectors regardless. We need to contribute and work as hard as we can.

I: Of course. Especially if we look from the global perspective and when you take into account emissions coming from elsewhere. We definitely hope that the findings we produce with the project will be recognized by the market.

How do you find collaboration with other country clusters and other partners on the project? Do you find it challenging or do you find it exciting to work with experts from other countries?

E:  Of course, it is a huge benefit. When counting the country clusters and Croatia, there are five different countries in the project. The benefit is also present in terms of the multidisciplinary approach of the project. At KTH, for instance, we have three different departments engaged. It’s very easy to fall into working with colleagues within the same department because those are the ones you see every day and they don’t really challenge your knowledge boundaries. This is really one of the bigger benefits – working with building sciences and the environmental department, as well as the architecture department, we actually have just as exciting discussions here, let alone with colleagues from other countries. It’s not difficult to work with an expert from other countries at all as they are all highly knowledgeable, highly engaged engineers, architects, and researchers. The companies have been really interested. When we had the annual meeting in Helsingborg where it was 40-50 people, we could have easily spent days in smaller meetings just discussing our work. I’ve been part of difficult research projects and this is definitely not one of them. Maybe in its scope, not in terms of people working on it.

 

I: Of course! When you work with highly motivated individuals, where everyone is an expert in their field, it can garner special results.

E: I would just like to add that this can most definitely be attributed to the way the project was written and the way it is led. The team around Satu Huuhka is doing a great job.

 

I: Agreed, definitely agreed. Let’s think about the future for a bit. We talked about the market uptake of the project results in the future – do you have some other impact that you would like to see 10, or 20 years down the line? For instance architects – do you think they will have enough creative range for new buildings?

E: I think so and I think this is quite intriguing. The reason I think so is because we have tested it in a design studio in project similar, but not attached to ReCreate. We tested the design with the reuse of prefabricated concrete panels and the students were a bit confounded at first because they are not educated to deal with them. But once they figured it out and understood the limitations they have, they could all devise a strategy or method for using the elements and many of them involved finding new forms or shapes or details of the buildings, which is directly attributed to the reuse of the panels. So they were shifting sizes of the panels, which left gaps or there were structural dimensions that led to certain rooms, sizes, or proportions. There were ways of combining elements that led to also different heights and widths of the buildings. All of these things may seem minor, but I think they are quite important. Now I’m wondering about if whether this is something that just happens in this type of shift or whether it is going to be a reuse style in the end which you can then understand that this is high-quality architecture because it is using reused elements and not because it has a certain color or look or proportion.

 

I: That’s something we will see with time. How the creatives will utilize it and what they will create down the line. With that in mind, do they have to deal with any technical constraints when reusing precast concrete elements?

E: Yes (laughs). From a technical and engineering perspective there are several issues, but I think that we have enough pilots now historically and Satu knew this when she was writing the project. There have been enough pilots in Germany and even in Sweden and we know that concrete has a longer material lifespan than a building has a socioeconomic lifespan. Cities are being developed and office buildings are being torn down to make room for housing and vice versa. The material can be reused but rules, regulations, financing, and business models is not adapted to this yet. So these are the big technical challenges that are not on the material side. Then, of course, there’s the whole question of knowledge. We’re not educated to deal with the existing environment and now it takes a lot of time to work that way, but in the future, we hope it will take less time.

 

I: Once the knowledge enters the curriculum, the dissemination of the knowledge should be more efficient. Actually, that is something I want your comment on – do you see the curriculums changing? Will there be some kind of specialization for reuse in that regard?

 On a general level, I think we’re seeing small research groups, and small parts of programs being adjusted towards sustainability issues and global climate change is the main driver behind the changes, but the ideas involved in ReCreate can influence them. One example is the Royal Institute of Art in Stockholm which opposed graduate degree in restoration architecture because they started a new program this year in restoring the recent past – the modernist heritage. They are actually starting a new program to engage from a building conservation and preservation perspective, and from a heritage perspective to garner a better understanding of the recent past. We’re not seeing that in architecture schools on the curriculum level yet, but we’ll see it, albeit as small changes.

 

I: So it is possibly still too early to talk about it. The changes might be incremental, but not paradigm-shifting.

E: I agree. I think there will be incremental changes, although the climate is screaming for a radical change

 

I: You were present at several architectural events where you represented ReCreate. What was the reaction from your peers and what kind of feedback did you receive from them?

E: Well, they are following ReCreate with great interest. For example, at the Lisbon Triennale we not only exhibited but I was invited as a speaker and when I held a presentation, part of it was about the content of ReCreate. It was received with great interest from all architects. We had architects from both North and South America, Asia, and Australia – almost all the continents were represented. They were all interested in the topic of Terra (the Earth) and different angles on sustainability and I would say it was a surprising and positive engagement with the ideas that I presented. It’s very positive. I usually try to lower expectations because the truth is that currently the rate of reuse in Europe is 0% and the goal is to move to 1% or 2%. Some people might think that we’ll have 50% of new buildings being made from reused materials 5 years from now but that’s not going to happen.

 

I: Understandable, but the proof of concept is definitely here and it’s definitely exciting.

E: Yeah! I was wondering how the architectural community of exhibiting architects, not just constructing architects, would react to the subject of reuse, but I have found that it was indeed highly regarded.

I: And they will certainly one day be a valuable part of that process. It’s a vast and long value chain of stakeholders and architects are certainly one of the more important parts as they will surely be one of the driving factors behind the uptake of reuse.

E: The exhibit in Lisbon was part of an overarching theme was ‘Terra’ and the exhibit we participated in was called ‘Cycles’ the curator Pedro Alonso from Chile and his partner Pamela Prado made a great selection of different academic professional practices and 15-17 practices that are all working with cycles in their daily projects. So ReCreate was shown among others. We have lots of friends out there and in that group, ReCreate was seen as very hands-on and that can have a very strong impact, which is because of the prevalence of prefabricated concrete as everyone is aware that it is being used all over as a resource.

 

I: Of course and it can certainly be deduced (even to the wider public) that the project can create great impact, it is very tangible and it can be pitched very easily to other people, which is why it is so widely acclaimed. Working on it can feel like being on the cutting edge of something really important.

E: Yes, exactly!

 

I: We’re nearing the end of the interview and thank you for your time, Erik. Do you have any closing comments or something you would like to mention with regard to the project?

E: I would just like to stress the collaborative aspect of the project. The EU projects are set up in such a way that you have to collaborate with partners from all over Europe and even across disciplines and I think this one is really critical because the effort to move towards increasing the amount of reuse will need experts from many different areas. It’s not just inventing a new material, putting it on the market, and seeing what happens, but this is about shifting a paradigm and moving the construction sector into a circular movement and we’re contributing towards that.

 

I: To top the interview off – who is Erik Stenberg when he’s not working on the project and what does he like to do in his free time

E: You’ll most likely find me in the woods or the mountains – basically far away from any architecture. I spend a lot of time with my family and friends in the backcountry, hiking, sleeping in tents, and walking across low mountains as we don’t have high mountains in Sweden. We can move across them easily as there are no dangerous animals, insects, or anything and we have potable water still so it’s a great way to recharge batteries from working hard all winter.

 

I: I also spoke to Satu and she said something similar, which is why I will use the opportunity to ask whether this has something to do with Scandinavian people always ending up on lists of the happiest people on Earth. Do you think this is true or is it overblown?

E: It s a little bit of a cliche but I think there’s some truth to it. I spent some time in the US when I was younger and I think the relationship with nature there was that nature is something that you conquer and you put up a fence and you own it somehow, apart from here where the dominant mindset is that we’re just borrowing some time from nature to be here and when I go outside the door I’m in the nature, I’m part of nature and I think that, as a mental construct, is something I try to cultivate. When I sit by a blue lake, it’s not because I’m interested in meditating, it’s because there’s some fundamental connection to being part of nature, instead of trying to dominate it, or water-ski. I’m not using the water in that sense. That’s an extreme form of affluence and richness. In most of the world, you don’t have to time or the money or nature to do that, but we’re very lucky in Scandinavia that I can do that. For example in my specific situation in Sweden where I can, for a few weeks a year, just be part of nature and not do anything else.

Erik Stenberg


February 17, 2023
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Not long after ReCreate was featured in an esteemed Chilean magazine, the project is at it again! Just recently, the project found itself sitting atop the #93 spot on this year’s Maktlistan – a list of the most powerful and impactful in Swedish architecture and design.

The list is created and published by Rum – a well-known and established Swedish architecture journal that recognizes and applauds great achievements in architecture and design, as well as the people behind them. Each entry in the list receives its own whimsy, positive (and sometimes even comical) comment and ReCreate was not ”spared” in this manner.

The authors of the text playfully acknowledged the aim of reducing carbon emissions through the reuse of precast concrete by saying that Mr. Stenberg ”will ensure that the rest of us will be able to breathe” because of the project.’

The ReCreate project would like to thank Rum magazine for recognizing the effort, expertise, and hard work that the Swedish country cluster, along with other country clusters and project partners are investing in the project.


January 18, 2023
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ARQ magazine, a non-profit architecture magazine published by Ediciones ARQ of the
School of Architecture at the Universidad Católica de Chile, published an article on the ReCreate project!

Swedish country cluster leader and esteemed professors Erik Stenberg and Jose Hernandez Vargas, along with our project coordinator and associate professor at Tampere University Satu Huuhka, shared their knowledge on the project and what it wants to achieve.

The article showcases the reasoning, as well as the historic and environmental context behind the idea for the ReCreate project, as well as the methodology and technology that underpin the project. Also, they give a breakdown of the pilot buildings, what were their functions before deconstruction and what elements will be gained from it.

But don’t take our word for it! You can check it out yourself by clicking on the link here!


November 7, 2022
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Leader of the ReCreate Swedish country cluster Erik Stenberg had another interview where he outlined the importance and advantages of the project.

The advantage of the concept is that the climate footprint and amounts of waste are radically reduced as it is much better to reuse entire elements than to grind down the concrete and use it as filling material, says Erik Stenberg.

THE STATE OF REUSING CONCRETE IN SWEDEN

Today, concrete elements are very rarely reused. At EU level, the figure is zero percent and in Sweden there are a few isolated examples. This is mainly because it is cheapest and easiest to build with new concrete. The business models for reuse do not exist and all parts of the construction sector are adapted to new materials, says Erik Stenberg. The goal of KTH researchers will be to examine the business chain for the reuse of concrete elements in the Swedish context and how it is affected by processes and regulations in the construction sector. Sweden actually has good conditions for reusing concrete elements because we built a lot with prefabricated concrete in the 1960s to 80s. Even if the elements are not manufactured to be taken apart and used again, according to Erik Stenberg, this is entirely possible.

ON THE SWEDISH PILOT SITE

The pavilion that the researchers built and displayed during H22 was a successful sub-project. The building consisted of 99 percent recycled material and the climate footprint had been reduced by 90 percent. The mistakes made gave the researchers new insights, for example that concrete must be handled carefully. The reuse also led to unexpected architectural solutions.

The elements were larger than we imagined, which resulted in a sturdier building. Solutions around doors and windows had to be adapted to this and the house’s pillars got a new design when they proved to be too heavy for the slab. Instead of being seen as obstacles, the limitations can contribute to interesting architecture, says Erik Stenberg.

Erik Stenberg also maintains a studio where students design buildings based on the concept in the research project. Erik Stenberg says that the students have shown that it is possible to design houses with good layouts and good light conditions from recycled concrete elements and that it is possible to design both row houses and point houses with elements from slatted houses.


October 5, 2022
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Erik Stenberg, a lecturer in architecture at the KTH School of Architecture and leader of the Swedish ReCreate country cluster, investigates the current practices of the reuse of precast concrete in the world.

He posits that offices with prefabricated concrete structures are the most common buildings that are demolished today, most often for housing construction, and that concrete from those demolished buildings is simply ground and that we create an unnecessarily big impact on the environment by doing so.

”When recycling, the product is changed and used for something else, or in the same area of use. When we are reusing, it is used once more in the same form and design.”

– “I’m afraid that someone will think that, like in Denmark, we will start grinding programs worth millions. It would be capital destruction because the houses are built with quality and will last at least another 150-200 years if they are dry and warm.” said Erik Stenberg.

According to him, Denmark also failed to meet the goal of reusing building elements in projects, in order to incorporate a better local history for residents, because the EU directive is that at least 70 percent of a building’s weight must be reused during demolition. However, in the Swedish ReCreate pilot study, the figure dropped to a staggering 99 percent!

He concluded that there were some mistakes in the project, but now they know where the obstacles lie in the construction permit phase, how access and quality can be ensured, and how the concrete elements can be reassembled, which enables an immediate reduction of carbon dioxide in new production.


June 10, 2022
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In the middle of Drottninghög, researchers from KTH are building a pilot building in the form of a pavilion from recycled concrete. The building is part of the H22 City Expo fair, which takes place between 30 May and 3 July.

The building stands on a plot where a preschool previously stood. KTH researchers have been able to use the base plate from the preschool for the building, which is 8×22 meters wide, 4 meters high, and consists of a few hundred tons of concrete. The building consists of 99 percent recycled material.

”The production of new concrete is very resource-intensive and accounts for 3-4 percent of the world’s total carbon dioxide emissions. By using recycled concrete in new buildings, emissions could be radically reduced. Our calculations show that by using recycled concrete in our pilot, we get a reduction of the carbon footprint by 96 percent compared to if we would have used new concrete. So this recycling of concrete points to a way forward.

Today, office properties are demolished from concrete that is perhaps 40 years old to make room for new homes. But that concrete has a much longer technical life than that, 100, 200, maybe up to 300 years as long as it is hot and dry. And if we are to access the carbon dioxide consumption in new buildings, we must have access to these heavy concrete frame elements.” – says Erik Stenberg, professor at the KTH University.

 

EU project on recycling of concrete elements

Professor Stenberg also leads the Swedish part of the EU project ReCreate – Reusing Precast concrete for a Circular Economy – whose purpose is to investigate how to reuse concrete elements in new buildings. The project, which is funded by the EU’s Horizon 2020 program, is led by the University of Tampere and the initiative also includes Eindhoven University of Technology and Brandenburg University of Technology.

Within the framework of the project, all four participating universities will produce two pilots – one digital and one physical. Unlike Tampere, Eindhoven and Brandenburg, KTH started with the physical pilot, the one that is now shown in Helsingborg, and will then make a digital one. The three partner universities’ first digital pilots can be viewed in the form of 3D-printed models of each donor building in KTH’s pavilion pilot.

There will also be descriptions of the various projects. But the exhibition’s focus is on Helsingborg and Drottninghög. Among other things, we present a project on recycling concrete in Drottninghög that some of our students at the School of Architecture worked on last autumn, says Erik Stenberg.

 

Challenge for architects

In addition to his role as leader for the Swedish part, he works with historical analyzes and a mapping of where concrete elements are, when and where they were built, in what form, by whom and for what. Two more KTH researchers are involved in the project – Kjartan Gudmundson from the Department of Sustainable Buildings and Tove Malmqvist from the Department of Sustainability, Evaluation and Governance, SEED.

Kjartan Gudmundson looks at issues such as quality assurance – concrete quality and the presence of hazardous substances – and digitization of historical and new information about concrete elements that can accompany them when they are used again, while Tove Malmqvist works with issues such as life cycle analysis, climate impact, business models, and regulations.


April 29, 2022
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Erik Stenberg, architect and senior lecturer in architecture at KTH – School of Architecture and the Built Environment (ABE) in Stockholm, answered a few questions on why reusing concrete is important in urban development projects.

 

Why is the reuse of concrete important?

– This is where the biggest environmental benefits can be made. If you access the concrete in the structure of houses, you can achieve the largest reduction in carbon dioxide.

 

 Why is it important in urban development projects?

 – It is becoming more and more important to look at the entire life cycle and carbon footprint of the entire urban development and not just individual buildings. We have to look at what was there before and what will come after. We need to make better use of the resources that are already above ground. Also, the historical dimension has nothing to do with carbon dioxide pollution, but with cherishing a legacy, taking advantage of what is good and building on it, and improving what needs to be improved.

 

What are the benefits of using reused concrete?

– This is exactly what we test in ReCreate. The thesis is that the concrete continues to harden during its lifespan and the technical lifetime is much longer than the service life of the buildings. Therefore, reused concrete should be better than new concrete both constructively and environmentally as we do not use and extract resources from the earth’s crust.

 

So concrete is made to last longer than the time we use it today?

 – It lasts much longer. The concrete you usually see is the one that is exposed outwards to the external elements and it is usually hit harder by rain, weather, cold, or salts (depending on where it is) than concrete that has been sitting hot and dry. If the concrete is hot and dry, it lasts forever.

 

What opportunities do you see when it comes to reusing concrete?

 – I look at the material and historical values and that we get a healthier discussion about how urban development should be done, and that we consume fewer resources when we build in the future. This is the biggest change that needs to happen, not just thinking ‘new’ all the time but rather that we take care of what we already have.





EU FUNDING

“This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 958200”.

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