Circular construction: building a sustainable future podcast

In a world where sustainable practices are gaining momentum, industries are seeking innovative ways to reduce their environmental impact. The construction sector, known for its resource-intensive nature, is at a pivotal moment of transformation. As urbanisation continues to rise, the need for sustainable construction practices becomes increasingly urgent. Circular economy principles offer a promising solution, aiming to reshape the industry's approach to materials, waste and energy.

In this episode of the Emerald Podcast Series, we speak with Professor Christina Chroni and Dr Spyridon Karytsas to explore how the construction industry can transition to a circular economy. Join us to discover how the adoption of circular practices can revolutionise the sustainability of urban development and pave the way for a more environmentally conscious future in construction. You’ll also hear about the challenges and opportunities in shifting towards circular construction and the key advancements shaping the field.

Speaker profile(s)

Professor Christina Chroni, Editor-in-Chief, ICE Publishing journal Waste and Resource Management, and Assistant Professor at Harokopio University of Athens. She holds a MSc and a PhD in Environmental Management and Technology. Her research interests are focused on Circular Economy and Sustainable Resources Management. Christina wrote an editorial on the circular economy for the Waste and Resource Management journal as part of a special issue on the topic. She has participated in 14 regional, national and international projects related to waste prevention and environmental technologies. 

Find Professor Christina Chroni via LinkedIn and email.

spyridon-karytsasDr Spyridon Karytsas is an Economist with an MSc in Sustainable Development and a PhD in Socioeconomic Aspects of Renewable Energy Sources. He collaborates with the Renewable Energy Sources Division of the Center for Renewable Energy Sources and Saving (CRES), Athens, Greece. He is a PostDoc researcher at the Department of Economics and Sustainable Development, School of Environment, Geography and Applied Economics, Harokopio University (HUA), Kallithea, Greece. Spyridon works on CO2NSTRUCT, a four-year research project funded by the European Union's Horizon Europe research and innovation programme. More information is available on the CO2NSTRUCT LinkedIn channel.

Find Dr Spyridon Karytsas via LinkedIn, X and email.

Podcast Host

rebecca-torrRebecca Torr is the Publishing Development Manager for Sustainable Structures and Infrastructures and works with authors and organisations in engineering subjects such as civil engineering and materials science to further the impact of research in the real world. As part of her hosting role on the Emerald Podcast Series, Rebecca interviews experts who use research to create real impact.

In this episode:

  • What is the circular economy and how does it relate to construction?
  • How difficult is it to implement circular economy principles in construction?
  • How might circular practices help reduce the construction sector’s carbon footprint?
  • How can waste within the construction supply chain be effectively repurposed? 
  • What can be done to improve collaboration efforts to meet circularity goals?

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Circular construction: building a sustainable future

Rebecca Torr (RT): Hi I’m Rebecca Torr and welcome to the Emerald Podcast Series. Today, we’re diving into a timely subject: the role of the circular economy in construction. This industry is a significant part of our economy and our daily lives, shaping the spaces where we live, work, and play. However, it’s also a major contributor to global greenhouse gas emissions, accounting for about 40% of the total. The concept of a circular economy offers a different approach. It’s about creating systems of use and reuse that can help us reduce waste and become more sustainable. In the context of construction, this means rethinking how we design, build, and maintain our buildings and infrastructure. We’re fortunate to be joined by two experts to discuss this topic. Professor Christina Chroni, Editor-in-Chief of the ICE Publishing journal Waste and Resource Management, and Assistant Professor at Harokopio University of Athens, and Dr Spyridon Karitsas, a PostDoc researcher at the Department of Economics and Sustainable Development, also at Harokopio University (HUA). They’ll share their insights, research findings, and practical strategies for achieving a circular construction industry. Hi, Good day to you, Christina and Spyros. It's lovely to see you both and I'm delighted to welcome you to the Emerald Podcast Series. With today we're going to be discussing the circular economy in the context of the construction industry. So perhaps we can just sort of start at the beginning. And if we can, if I can ask you to define what is circular economy, circular construction, and how does it promise to revolutionise the sustainability of urban development in the long term? And Christina, maybe I can come to you for that beginning question. Thank you.

Christina Chroni (CC): Yeah, well, circular construction refers to an approach in urban development and building design that aims primarily to minimise waste and resource consumption. This is achieved through certain, as a priority the use of recycling and renewable materials, designing for this assembly and reusability and implementing efficient construction techniques that reduce environmental impact. It is quite important because as we all know, the conventional construction industry bears significant environmental burdens, including extractive wasteful use of natural resources, excessive energy consumption and pollution, of course, and we should not forget that, in the EU alone the construction sector accounts for approximately 30% of the annual waste generation. At the same time, buildings contribute to about 40% of the EU energy consumption, so, by incorporating materials retrieved by waste, we believe that this adverse impacts can be mitigated. How the circular construction promise to revolutionise the sustainability of urban development. There are some ways, there are several ways. One of these is that circular construction, as it aims to use materials more efficiently, it does emphasise the reuse and recycling of construction waste materials. And this reduces the demand for new resources minimises the environmental impact associated with extraction, the processing, the transportation of raw materials. One more way is through the design for disassembly, we all know that buildings are designed with the idea that their components can basically dismantle and reuse or recycle at the end of the lifecycle. So this is what circular construction promotes. This could encourage modular construction and the use of standardised components that can be repurposed in future projects.

RT: Amazing. Thank you. Um, it's really interesting, isn't it? Sort of there's like the benefits to adopting a circular economy in construction seem to be very varied and and sort of cover lots of different areas. And I don't know if Spyros wants to sort of comment on the economics side of it because obviously that's your sort of speciality. I mean, your background is specialised in that. So I don't know if there was anything you wanted to add? 

Spyridon Karytsas (SK): Well, yeah, first of all, I could add to very interesting ideas provided by Christina. That apart from the recycling, reusing practices included in the construction sector, perhaps it is of interest to examine higher practices in terms of hierarchy of circular economy, such as rethinking or refusing, these are two practices of circular economy. For example, when we are referring to the construction sector, what is rethinking? It has to do with the idea of sharing spaces either on a residential level people living together, not family members, but sharing with someone else, your house or in terms of the professional life sharing your office space with other people. When we are referring to the refuse practice, how is it connected to the construction sector, we could say, refusing to use the conventional materials, bricks, cement steel, and aiming to use biomaterials or innovative materials, such as 3d printed materials or carbon fibre? So I guess this is something more for the future, not so easy to do right now. But perhaps the future could go somewhere towards that. 

RT: Thank you so much. I mean, it's a no brainer that that's the direction that we need to go into. But it will be interesting, if you could sort of talk about the barriers and why it's taken such a long time, why is it taken such a long time for the construction industry to move towards a more of a circular economy model? And are there any strategies that can be implemented to overcome those challenges?

SK: Based on our work, we have seen that these the barriers related to the diffusion and the development of the circular economy practices in the construction sector have been examined in the past mainly based on the stakeholders, perceptions, stakeholders that are active in the construction sector. And in general, we could categorise the barriers into economic, informational, political, technological, and institutional, when we are referring to economical, we could include economic, financial and market themed barriers. And what do we mean here, mainly the lack of financial aid or subsidies, in order to increase circular business models, the informational barriers are also related to the societal and cultural dimensions. And here, we have to do with lack of awareness, lack of knowledge, and the the behavior of consumers how to change the behavior of consumers, political barriers, also connected to the regulatory and legislative aspects have to do with the absence of government policies, the absence of regulatory instruments and fiscal actions. Technological barriers, as the category name says, has to do with the lack of technologies and relevant infrastructure. And finally, institutional barriers have to do with the lack of knowledge, the lack of the behavior that should be required from the part of key stakeholders, meaning the the stakeholders of the construction industry. So very brief, these are the, the the main barrier categories.

RT: I mean, you've really outlined that very well, and it's actually quite staggering, how many barriers there are. I mean, I never would have thought about it in that detail. You know, sort of it does span every aspect of what it takes you know, to implement any construction and and I think, you know, the the legislation part as well is something that, the whole industry could be really willing to to change but if that's not in place, then and standards are not there and measurements, are not there. I mean, it must be very tricky to go forward. So, I don't know if Christina, if you have anything that you can share on sort of what would be the first step. I mean, I know, obviously, that everyone's trying to push in this direction. And there are there are, there is a big push from government, and there's a big push, you know, from the industry as well. But it's not across, you know, maybe like the people doing the work on the ground. So, you know, what is going to really, you know, turn up the dial in making this happen, you know, in in the next sort of few decades when we really need it?

CC: Well, first of all, we have to consider that the construction value chain involves a lot, it is a fragmented value chain. So this involves numerous factors and processes, and this can make it very challenging. So a strategy that can overcome these challenges, we have to take this consideration. So however, we can also have a lot of ways, strategies to overcome these challenges. Collaboration, and again, and engagement would be the number one, meaning that we have to find foster collaboration among all stakeholders across the construction value chain, which would include designers, builders, materials, or suppliers, policymakers, if we do not engage them, and help them collaborate, push them collaborate, the strategy, strategy cannot be implemented, cannot be successful one. So we have to develop or promote collaboration for them all to jointly develop and implement circular strategies, then we have to advocate for policies and regulations that give incentives to circular construction practices. What I mean by this in incentives, such as tax incentives, for using recycled materials, or requirements for sustainability paid and certifications, as you mentioned earlier, we have to also enhance education and training across the construction professional, all the groups of types of professionals. And of course, we have to enhance the value of research and development. Because, okay, we can say we can demonstrate that we need recycling materials, but we have to prove that these materials are of course of high quality, and that can they that they can last for long time. So that would be a good place. I think a good start to tackle these barriers.

RT: Brilliant. Thank you. I think that's that's really helpful. And yeah, it's going to require everyone being committed to making, making this happen. I wonder if we can talk about your specific backgrounds and areas. And I know Spiros, you were mentioning that you collaborate on an EU funded project. And I wonder if you can sort of talk about what that project is about. And its aims, because you're looking to model the role of circular economy construction value change for a carbon neutral Europe. Obviously, that's that sounds like a very collaborative project that quite an intense project as well. And I just wondered what your sort of what your aims are and how you're going to achieve it really?

SK: Yeah, yeah, of course. This is the CO2NSTRUCT project, CRES – Center for Renewable Energy Sources and Saving is part of the consortium of this project. It is funded under the Horizon Europe framework. It started in 2022, and it will end in 2026. And we are seven partners from seven countries. Apart from Greece, we have a partner from Germany, Denmark, Italy, Spain, Portugal and the United Kingdom. And the coordinator is the Technical University of Denmark. Now about the the concept of the project and what it aims to do. We work on defining a circular climate mitigation for a framework in order to extend energy and climate mitigation models, such as the times model. To be more specific the times model includes all these steps from primary resources through the chain of processes that transform, transport, distribute and convert energy into the supply of energy services demanded by all consumers. Of course, this is the first step as the the work that we are performing can serve as a basis for other climate mitigation models. So not only for the times model, but it can be used in a more general way. The project focuses on six carbon intensive construction materials, steel, cement, bricks, glass, wood, and insulation, and the project includes various activities. First of all, we are mapping the value chains of the six materials, examining any feedback loops, the rebound effects that also Christina mentioned before and mentioned how important they are. Also, social and environmental externalities are taken into account. And when we're talking about that, we mean GHG emissions, other air pollutants water usage, the energy embodied in all these activities, as well as societal impacts, including creation of employment, or the creation of potential inequalities. Through this work, we are going to create Circular Economy scenarios in order to see the role of circular economy practices towards climate mitigation within the European Union, plus the United Kingdom, in a short term, but also in the long term. We are working on the examination of of the behavioural consumers, behavior on circular economy practices, as well as on stakeholder engagement. When we are talking about stakeholders, let's say the key stakeholders, policymakers, decision makers, or people from the industry. What we have done so far from our part is to examine consumers behavior, we have carried out a survey in nine countries, the seven countries that I mentioned before, which are partners to the project plus, Poland, and Romania. I could say that it is a very interesting and innovative research based on the literature review that we perform. We didn't find any previous research examining consumers attitudes, intentions, behavior on circular economy practices related specifically to the construction sector. So first of all, we examined their levels of awareness and knowledge of the different circular economic practices. What we saw was that, of course, most of the people knew recycling, reusing, renovating the most, let's say, well known practices. But on the other hand, practices, such as rethinking or refusing that I also mentioned before, are not so well known across the general population. Of course, a lot of differences were identified between the nine countries included in the survey, we had a sample of 4,500 people, so quite significant, substantial sample. Apart from awareness and knowledge, we explored people's intentions and willingness either to adopt specific practices and willingness to pay either positively or negatively meaning would they pay more? Or would they pay less in order to take part in specific practices? So it was quite a large survey, including a lot of countries, a lot of interesting results, and in the following months until the end of the project, and perhaps after that, we would like to publish all our results, I believe that they would be quite interesting for the whole community. And as a last thing, in order to connect this work to the whole project, in order to create the survey, we had a lot of discussions and feedback from our partners that were more on the technical side of the circular economy practices. And the data that we collected, or some of the data that we collected will be used in the models, for example, how often do people intend to renovate their house, a light innovation, medium innovation or a full renovation? Do they intend to use recycled insulation materials? What is the percentage in each different country?

RT: It's absolutely fascinating. And I think, you know, we're really fortunate that you could share that with us because I think, a live research project, which is what you're in, you know, you don't have all the answers yet, but you're looking into areas that have never been studied before. Yeah, Christina, it'd be great to come to you as well, because obviously, you are an expert in circular economy, in construction. And as you mentioned, you're the editor in chief for the Journal of waste and resource management. And you recently published a themed issue which looked at how waste can be repurposed and incorporated into construction for improved material quality and performance. And I was wondering if you could tell us about the themed issue and maybe some of the innovations that were discussed, and perhaps some of the key takeaways and if this is an area that you might come back to in the future?

CC: Yeah, well, it is an inside insightful themed issue, at least in my opinion, is, I believe, I really believe that it will play a leading role in advancing the field. So it was it compromised three papers, which I believe provide the readers with promising construction applications of waste. The first two papers addressed one of the major, the priority challenges in the transition to a circular economy in the construction area, which is the recovering of construction and demolition waste. So the first paper of this issue, it was authored by the team of Salamoni it investigates the addition of recycled fines from construction and demolition waste in cement composites. I believe they demonstrated, they proved that the considered industrial construction and demolition waste fine aggregate shows promise as a material for replacing natural silica sand, it is an important conclusion and this with minimal loss of workability, strength and gains in resistance to alkali silica reactivity. So, it is a quiet important work. The second paper was authored by the team of Arruda, they conducted a laboratory scale assessment of the feasibility and potential benefits of using construction demolition waste mixed with soils in embankment they also so, this mixtures can be considered feasible for possible use in embankments. The third paper is quite different actually, regards to quite different waste stream, plastic waste. We are all familiar with plastic waste, but this is another approach. The use of recycled plastic to improve the performance of asphalt is what is quite of high interest for the construction industries. So this team tried to modify hot mix asphalt binders with three different types of recycled plastics. And their results and conclusions were quite amazing. They saw that the use of recycled plastic may lead to the reduction of resilience and traditional construction materials. While address the plastic waste generation issue. So to wrap up these papers, the three papers highlights that embracing waste utilisation and construction and demolition is possible and may be feasible. Embracing waste utilisation and construction is a transformative step towards achieving the circular economy. And I believe that this thematic is a thematic that we have to go back and maybe organise a new themed issue, maybe this year or next year, because it's of high interest for the readers of their waste resource management.

RT: Fantastic! I mean, it's really promising to think that they can use plastics especially because obviously, you know, that's whether there's such a big problem with plastics. So, I mean, if they can repurpose plastics, and you know, it can be used for something in the future, you know, that it could last for, you know, for centuries or something. I don't know how long, you know what the durability of it would be. But if, that's very promising research, isn't it? And it is something that, you know, hopefully that, like you said, there's a lot of interest in that. And hopefully, it's something that can sort of be replicated on a sort of a wider scale. I wonder in your opinions, what needs to happen for sort of waste repurposing in construction, and that kind of circular economy practice? What needs to happen for it to become mainstream? Would you say? And how long is it going to take?

CC: Hopefully, not decades, hopefully, of course, we have to enhance research and development. We have to, to support research teams, to do some more research and of course, to collaborate with industries and the stakeholders in the construction industry. We also have to try to enhance upcycling and reprocessing. Meaning that we have to explore opportunities to upcycle construction waste into higher value products. And we have to collaborate with recycling facilities. We have to save them as resources. But we have to collaborate with them in order to ensure that construction waste is properly collected, transported, processd, we need to collaborate, this is the conclusion, I guess.

RT: Collaboration. That's fantastic, thank you. And I think just to sort of wrap up our session, and it's been absolutely fascinating, thank you both for sharing your insights and your ideas. Where do you see the future of circular construction practices taking place? I mean, are there any key advancements or trends that you think will shape the field in the coming years,

SK: The only, the main thing that I could mention is that apart from the main practices such as reusing, recycling, which I think Christina can describe, much better than me, I could, I would like to give a focus on the practice of refusing, meaning to use natural resources for example, wood, of course, in cases that this is something that can be done or focus on innovative materials or bio based materials. So, I would like to target my you know, my final my final ideas on that, yeah.

CC: Advancements in material innovation for, first of all, I believe, yes, we will explore novel biomaterials may be or bio based composites that offer sustainable alternatives, that could be a good advancement in material innovation, adoption of digital tools and building information modelling, I believe that we implement smart sensors maybe or Internet of Things devices, in order to monitor to real time monitor the building performance, condition, whatever. And I believed that we were going to have material passports or at least I would like to have, we should have material passports and last but not least, circular design and prefabricate fabrication. Me meaning that we should give greater emphasis on circular design. Try and get set as priority modularity, adaptive ability or simply for reuse and recycling.

RT: That brings us to the end of our discussion on circular construction. A big thank you to our guests, Professor Chroni and Dr Karitsas, for sharing their expertise and insights. Thanks for listening, we hope you found this episode interesting and informative. You can find more information about my guests, and a transcript of the episode, on our website. A final thanks goes to Podcast Producer Daniel Ridge, and the studio This is Distorted. This is Rebecca Torr, signing off. Looking forward to our next engaging conversation. See you next time!