reuse - Recreate

January 15, 2025

Arlind Dervishaj, KTH

Concrete is used everywhere—in buildings, cities, and infrastructures. However, due to the large quantities of concrete used worldwide, it contributes to around 8% of global CO2 emissions [1]. While efforts are being made to reduce its carbon footprint, such as by using supplementary cementitious materials, an often overlooked solution is reusing concrete.

The ReCreate project aims to foster a circular economy in the construction industry by reusing precast concrete elements from existing buildings in new construction projects. To support this goal, our study investigated the reuse potential of structural concrete elements, evaluating three key factors: the remaining lifespan of concrete, natural carbonation (ability to reabsorb CO2 over time), and embodied carbon savings achieved by reusing it [2]. Reusing concrete has multiple benefits as it prevents waste, reduces the need for new raw materials, and significantly lowers life cycle CO₂ emissions. However, it is not as straightforward as it looks. The structural integrity of concrete with reinforcing steel can be compromised over the lifetime of buildings, if the right conditions for corrosion emerge, such as from the carbonation of the concrete cover and the presence of moisture at the rebar interface [3].

Circular Construction concept for concrete

Based on established carbonation models, we proposed a digital approach for estimating the remaining service life of concrete elements. The digital workflow also estimates the CO2 uptake from natural carbonation. We tested the workflow on an apartment building with a precast concrete structure, built in Sweden in 1967 during the Million Program. The building was modelled digitally, and material quantities and exposed surface areas of concrete elements were automatically extracted.

Digital workflow and building model

A key aspect of the study was the comparison of carbonation rates specified in the European standard EN 16757:2022 with rates derived from measurements in the ReCreate project and the literature [4,5]. This comparison revealed that the carbonation rates in EN 16757 may be overly conservative and hinder the reuse of concrete elements. We argue that relying on contextual carbonation rates, such as the ones in our evaluation, from a previous condition assessment, and new on-site measurements, is crucial for making informed decisions about concrete reuse. The study also addresses the recent RILEM recommendation on revising carbonation rates in standards like EN 16757 and CEN/TR 17310:2019 [6].

Using carbonation rates from EN 16757:2022, led to the conclusion that most of the precast elements would not be reusable (i.e. carbonated concrete cover and past the initiation phase for service life). The standard assumes a high rate of carbonation for concrete, especially indoors, which reduced the concrete’s remaining service life; concrete cover for indoor elements was expected to carbonate the earliest, 23 years after initial construction. However, when using the contextual carbonation rates derived from the ReCreate project’s investigation and recent literature, all elements were deemed suitable for reuse, with sufficient remaining lifespan. Plaster and other coverings slowed carbonation significantly, extending the service life of concrete. Additionally, carbonated concrete elements can be reused, but further considerations should be made concerning the environment and exposure conditions in the new building. Recommendations from ongoing research in ReCreate are expected for concrete reuse in new buildings.

The study also assessed the CO2 uptake of concrete over its life cycle, including the first service life, a potential storage period prior to reuse, and a second service life when reusing precast elements. The findings indicate that the CO2 uptake estimated using the EN 16757 rates was significantly higher than the estimate based on contextual rates. Additionally, the study demonstrated that the climate benefits of reuse exceeded those of carbonation, which accounted for less than 6% compared to the emissions associated with the production and construction of new precast concrete buildings. This highlights the importance of prioritizing reuse as a key strategy for reducing the climate impact of buildings.

Furthermore, the study investigated the implications of three different allocation methods for assessing the embodied carbon of concrete over two life cycles. The analysis included scenarios with and without carbonation uptake. The results indicated that the Cut-Off method was the most advantageous for reusing the existing building stock, followed by the Distributed approach, while the End-of-Life approach was the least favorable. The study emphasizes that the reuse of existing building stock offers a substantial opportunity for mitigating climate change and fostering a circular built environment.

Comparison of three LCA allocations, over two life cycles

References

[1] Monteiro PJM, Miller SA, Horvath A. Towards sustainable concrete. Nat Mater 2017;16:698–9. https://doi.org/10.1038/nmat4930.

[2] Dervishaj A, Malmqvist T, Silfwerbrand J, Gudmundsson K. A digital workflow for assessing lifespan, carbonation, and embodied carbon of reusing concrete in buildings. Journal of Building Engineering 2024;96:110536. https://doi.org/10.1016/j.jobe.2024.110536.

[3] Angst U, Moro F, Geiker M, Kessler S, Beushausen H, Andrade C, et al. Corrosion of steel in carbonated concrete: mechanisms, practical experience, and research priorities – a critical review by RILEM TC 281-CCC. RILEM Technical Letters 2020;5:85–100. https://doi.org/10.21809/rilemtechlett.2020.127.

[4] European Committee for Standardization (CEN). Sustainability of construction works – Environmental product declarations – Product Category Rules for concrete and concrete elements (EN 16757:2022) 2022. https://www.sis.se/en/produkter/construction-materials-and-building/construction-materials/concrete-and-concrete-products/ss-en-167572022/ (accessed November 26, 2023).

[5] European Committee for Standardization (CEN). Carbonation and CO2 uptake in concrete (CEN/TR 17310:2019) 2019. https://www.sis.se/en/produkter/construction-materials-and-building/construction-materials/concrete-and-concrete-products/sis-centr-173102019/ (accessed September 26, 2022).

[6] Bernal SA, Dhandapani Y, Elakneswaran Y, Gluth GJG, Gruyaert E, Juenger MCG, et al. Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete. Mater Struct 2024;57:173. https://doi.org/10.1617/s11527-024-02424-9.

by ReCreate project

January 8, 2025

An essay on a circular design by the Principal of LIIKE Oy Arkkitehtistudio, Eric Rawlins.

I recently posted a graph on social media displaying the percentage of recycled material used in construction across EU member states. Finland places second but last, with only Romania reusing less material in construction. Reactions were astounding, ranging from questioning the graphs’ depiction to demands to clarify what are the materials in question at all, to claims that circularity is a fringe issue since it isn’t linear, to how spot on this finding is, and how high a mountain we have to climb.

Finns are pragmatic, focusing often – pardon the pun – on concrete solutions rather than philosophical debates. To paraphrase Mies van der Rohe, “getting things done” is crucial, whereas pondering is not quite so.

Albeit that the ReCreate project is focused on technology, the practice of “getting things done”, in this case how to integrate refurbished materials into a linear practice, might be considered less of an end. After all, even at its most utilitarian construction is always a means to another end. While construction processes are often viewed as self-orienting, there are ultimately merely an end to a larger purpose. Subsequently, buildings are designed by architects for the purpose at hand, less than the construction technique available.

This forces us to consider what exactly are we attempting to achieve with the buildings we build, and why is a particular purpose justified, particularly in a circular future. If by definition we are motivated by a low-carbon world and premised by the availability of reusable material(s), should we not consider how necessary construction is in the first place? And then which purposes, solutions and outcomes can be considered acceptable?

Anticipating these changes suggests a transformation where architecture evolves from a service to a deeply analytical and creative act, subscribing value, creating purpose, and resolving outcomes within material constraints. The need to transition to a circular economy emerges from a century of change, pushing us to move away from 20th-century models and technologies. To relinquish what was, in favour of what should be.

ReCreate already indicates that partners and stakeholders are becoming increasingly aware of reuse as a viable and realistic solution for a sustainable future. Not to perhaps entirely replace the linear world, but offer a complimentary path. As communities grow increasingly aware of the environmental impacts of post-war growth, the integration of reused materials in construction is beginning to show as a route to the future. One increasingly resonates with younger generations less inclined to believe in the world views of post-war extractive regimes.

This paradigm shift also suggests a reinvention of design, building, financing, and regulatory practices, presenting opportunities in fields beyond the construction sector. Where traditionally people see waste, we see the literal and conceptual foundation for a shift in societal values, business models and design practices. Reusing precast concrete elements might not represent a leap for mankind, but it does represent a significant step towards circularity in construction.

Our preparatory design studies navigate some of the constraints and possibilities presented by the selection of concrete elements and structures, retrieved from the Finnish deconstruction pilot. The emphasis is to study how to create an architectural solution to a given layout, which remains as faithful as possible to an original new build solution. Even in early studies, we have identified promising design strategies aimed to explicitly display the refurbished elements, as well as defined lines of study regarding potential hybrid structures, which may lead to real-life solutions that most likely would not be considered otherwise.

Our aim is to use the constraint-driven condition to establish an architectural language that will visibly express the ethos of reuse and sustainability, and encourage a dialogue between the old and the new, where our pilot building tells a story of continuity and renewal.

While it is said that history does not repeat, it merely rhymes, one is tempted to see similarities between today’s world and the world of the avant-garde. Transitioning to circularity is a phase change. If history is any measure, employing deconstructed material is a new practice which will manifest as a reinterpretation of architecture. Just as in the early 20^th century, societal and technological evolution manifested in the work of Le Corbusier, Mies van der Rohe and Alvar Aalto resulting in a new architecture as a concrete outcome, a societal construct and a value expression, it would only seem only logical to expect something similar from the Green Transition.

In this case the use of refurbished concrete represents more than a technical solution to environmental challenges—it becomes a manifesto for societal change, literally embodied in the structures we inhabit. By reevaluating how we build and what materials we use, we can instigate a profound shift in values, business practices, and architectural design.

Our take on circularity in construction is one where, respecting what we have, our maxim becomes: Function Adapts to Form. To quote Alvar Aalto:

“Nothing old is born again. But it doesn’t go away completely either. And what once was will always be again in a new form.”

Eric Rawlins

Architect

Principal

LIIKE Oy Arkkitehtistudio

Figure caption: Reusing building material from the existing stock is first and foremost an opportunity. (Photo: Tampere University / Heikki Vuorinen)

by ReCreate project

December 10, 2024

Leena-Aarikka-Stenroos-Mikko-Sairanen-Linnea-Harala-Lauri-Alkki_ReCreate-project_Horizon-2020-1280x670.png

As part of the ReCreate project, WP7 plays a pivotal role in developing circular business models for concrete reuse, contributing to the overall goal of establishing sustainable and economically viable practices in the construction industry. In this interview, key team members from Tampere University—Leena Aarikka-Stenroos, Mikko Sairanen, Linnea Harala, and Lauri Alkki—share updates on their progress, insights into co-creating business models, and the value propositions they’ve explored for expanding the reuse business across Europe.

Can you share some updates on what WP7 has achieved so far within the ReCreate project?

LEENA: Absolutely! We’ve hit two important milestones. First, we’ve mapped out how different countries approach the reuse of building materials, focusing on three specific cases. This has helped us understand how actors in the construction industry are involved in reusing concrete elements. Second, we’ve started developing business models that show how companies can profit from reusing concrete. Moving forward, we aim to keep refining our understanding of how these processes work across different countries to ensure the project’s success.

WP7 focuses on developing circular business models at both company and value chain levels. Can you explain how these business models are being co-created and how they contribute to the project’s goals?

MIKKO: We’ve created business model canvases to map out how companies can profitably reuse concrete. These canvases cover three levels: the overall system, individual company profiles, and specific process stages like quality control or storage. Different countries have slightly different setups. For instance, in Germany and the Netherlands, some companies manage most process stages from deconstruction to reconstruction, while in other countries, multiple companies handle different parts of the process. By analyzing and mapping these models, we help companies figure out how to make this approach profitable, both in the short and long term.

LEENA: I’d like to add that we’ve noticed a lot of variation in how these models work across different countries. Some companies only handle deconstruction, while others do both deconstruction and reconstruction, which affects their business approach. This diversity helps us understand how different roles and processes can be profitable.

Could you share some insights into the value propositions, value creation, and value capture strategies explored within WP7 for concrete reuse?

LINNEA: We found several ways that reusing building components can create value, either through cost savings or new revenue. Key factors include the design and condition of the donor building, location, logistics, and efficient project management. Regulations and industry acceptance of circular practices also play a big role in creating value.

LAURI: In the Netherlands, we saw that “one-on-one” reuse, where components are taken from one building and directly used in another, is the most profitable approach at the moment, but of course it requires a key actor who can take responsibility along the process from deconstruction to construction. Overall, in all pilot projects companies also gained new skills, especially in deconstruction and design, which are critical to enabling component reuse.

MIKKO: In Finland, making concrete reuse profitable is a challenge, especially due to high deconstruction labour costs. Success depends on strong regulations, efficient demand management, and clear strategies for reuse. The Netherlands and Germany are good examples of how to do this effectively.

LEENA: Learning is key. Companies may face higher costs at first, but as they gain experience in deconstruction and reuse, they become faster and more efficient, lowering costs in the long run.

One of WP7’s objectives is to identify strategies to expand the reuse business across Europe. Can you explain these strategies and how they deal with the local nature of the building industry?

LINNEA: We’ve considered the idea of creating a marketplace for concrete elements, which could help expand reuse. However, there are challenges in making this work locally and deciding who would manage and profit from it.

LEENA: Construction companies often work in different countries, and they can apply what they learn in one place to another. For example, a Finnish company in our project wants to use its new practices across all the countries they operate in. However, different countries interpret regulations differently, which can be a challenge.

LAURI: That’s a great point, especially since we have large companies like Skanska and Ramboll in the project. Sharing knowledge between countries is key, and some countries offer great examples for others to learn from.

How does the analysis of safety and health aspects translate into economic value within the concrete reuse ecosystem, and what measures are being considered to enhance safety and health in this context?

LEENA: Safety and health analysis is crucial but incurs costs, such as for quality checks and safe practices. We need efficient ways to integrate these assessments, potentially using digital technologies, to minimize expenses while ensuring safety, which is vital for economic value in concrete reuse.

LAURI: In our discussions with Skanska, safety concerns about reused concrete elements were prominent. It’s essential to communicate to customers that these elements are thoroughly tested and safe to build trust in the market.MIKKO: Brand reputation in construction hinges on safety and quality. Companies must meet these expectations to protect their image, making quality a critical aspect of our analysis.

LINNEA: Work safety regulations can vary, affecting project costs and feasibility. For instance, Germany has stricter safety standards compared to Finland, impacting deconstruction costs.

Can you elaborate on the connections between social and legal barriers and economic value within the concrete reuse business models?

MIKKO: Social challenges, like public trust in reused concrete, can influence demand and economic value. Legal barriers, such as product compliance and market access issues, also affect economic viability. Balancing these factors is essential for successful business models.

LEENA: The Finnish Ministry of Environment values expertise in creating supportive regulations for circular processes, aligning with our project’s goals to shape favourable EU and national legislation for component reuse.

LAURI: In Finland, there’s confusion over classifying deconstructed elements as waste or not, which complicates handling and permits. This uncertainty has caused delays in the pilot project.

LINNEA: Ownership of elements is vital; in Finland, construction companies retain ownership from harvesting to sale, simplifying the process.

How do you envision the role of technology, societal acceptance, and regulatory factors in shaping the economic aspects of concrete reuse, as discussed in Task 7.4?

LEENA: Technology, societal acceptance, and regulatory factors are interconnected in influencing concrete reuse economics. Advancements like automation and digital modelling enhance feasibility and efficiency. Societal trust in reused materials boosts demand, while balanced regulations are needed to support innovation without hindering business. Effective communication and marketing can foster societal acceptance, helping to increase demand for reused concrete elements.

WP7 focuses on identifying easily achievable improvements and economic benefits in concrete reuse. What are some of the “low-hanging fruits” that have been identified, and how can they accelerate the transition toward more sustainable building construction?

LEENA: We’re identifying simple improvements, or “low-hanging fruits”, that can promote concrete reuse. While still gathering data, we see that small changes can encourage companies to embrace reuse without a complete overhaul.

LAURI: A key improvement involves rethinking collaboration roles in construction. Embracing broader collaboration beyond traditional roles can significantly enhance concrete reuse efforts.

MIKKO: Effective data management and communication among all parties are crucial. Knowing where deconstructed elements will be reused and planning accordingly can optimize the entire process.

In your journey with the ReCreate project, could you share a memorable experience or moment that has had a significant impact on your perspective or approach to sustainable construction and circular economy initiatives?

LINNEA: As a doctoral researcher, my most impactful experience was visiting the German cluster, where I saw how cost-effective building component reuse transformed old elements into new spaces. It was enlightening.

LEENA: A key moment for me was realizing the potential of concrete reuse in reducing emissions and seeing the project’s problem-solving spirit that drives sustainable improvements.

MIKKO: Visiting Lagemaat in the Netherlands was eye-opening; seeing their profitable concrete reuse operations changed my perspective on feasibility in this area.

LAURI: My memorable moments include witnessing the Lagemaat operations and the progress of our Finnish pilot project, both highlighting the project’s impact.

In summary, WP7’s efforts within the ReCreate project are forging a path toward a more sustainable and economically viable construction industry through the development of circular business models for concrete reuse. The insights gained from diverse country analyses, coupled with innovative strategies for collaboration and technology integration, underscore the potential for significant advancements in this field. By addressing safety, social acceptance, and regulatory challenges, the team is not only enhancing the viability of reused concrete but also building a robust framework for future circular practices. As these initiatives continue to evolve, they hold the promise of transforming the construction landscape across Europe, making it more resilient and environmentally responsible.

by ReCreate project

October 18, 2024

Arnaldur Bragi Jakobsson

Second Wind explores the potential of reusing pre-cast concrete elements from an obsolete apartment building in Helsingborg, Skåne County, Sweden.

As part of the ReCreate initiative, which encourages the sustainable repurposing of concrete components, I collaborated with Helsingborgshem, the city’s municipal housing company, to develop a new rowhouse typology of approximately 100 m², alongside a two-story multifamily apartment building on the same plot.
The project aimed to minimize modifications to the existing structural components, preserving their original form as much as possible while adapting them to new uses. The rowhouses, arranged in an L-shape with a southwest-facing courtyard, serve as rental units and highlight the potential of reused materials in creating modern, functional spaces. The apartment buildings, located on the north and south sides of the site, further demonstrate the versatility of these repurposed elements.

Throughout this process, I sought to maintain a connection to the original architectural context of the Drottninghög area, respecting its mid-20th-century character while introducing new, sustainable housing solutions. This project illustrates the significant environmental benefits and creative opportunities in reusing existing building materials, paving the way for more sustainable construction practices.

Rowhouse plan (Arnaldur Bragi Jakobsson)

by ReCreate project

August 30, 2024

Lina Brülls, Graduate Architect and Master’s Student in the Computer Science Program at Chalmers University of Technology

The master’s thesis “Resource-Driven Design” explores how the design process can be adapted to facilitate the reuse of structural concrete elements. Research done in the thesis indicates that current design and data processes are not easily translatable to reuse scenarios, where preexisting structural and geometrical attributes of materials must be considered. Based on this, three key research questions are formulated: identifying the necessary data for the reuse design process, developing a Grasshopper Rhino plugin for data integration, and applying this tool in case projects with the aim of optimising reuse.

The developed Grasshopper plugin, programmed in C#, enables data handling from Excel into Rhino. It generates structural modules from reused hollow-core and load-bearing wall elements based on desired design parameters. The tool was tested in three architectural projects on Siriusgatan in Bergsjön. Regular consultations with the ReCreate team at KTH provided helpful expertise and feedback throughout the development process.

The study’s findings suggest that integrating data early in the design process can improve the efficiency and feasibility of reusing structural elements. One key challenge encountered in this project was planning within the constraints of the generated load-bearing modules. Including glulam beams introduced necessary flexibility, enabling adjustments in level height and allowing the removal of some load-bearing wall elements.

by ReCreate project

August 9, 2024

Tommi Halonen, project manager, City of Tampere, Finland

Sometimes I get asked: ‘Why is the City of Tampere participating in ReCreate, and what is our role in the project?’ It might be much easier to see why a university or a construction company is taking a part in a project where the goal is to (de)construct buildings in a novel way. But what is the city doing in ReCreate, especially when the deconstruction pilot was not a public building? From my viewpoint, cities have in particular the following two roles to play in the circular transformation:

Role 1: developing public processes that enable the implementation of CE solutions.

First, cities have a significant role as regulators in the construction industry. If there are any issues related to public regulation that do not allow reuse or make it extremely bureaucratic, it is impossible or very difficult (or expensive) to create business out of ReCreate or any other circular solution. There are especially two matters that are regulated by the city authorities that are worth paying attention to: (1) implications of waste legislation and (2) product approval practices.

(1) During the ReCreate project, we’ve had multi-stakeholder discourse in Finland about whether reused building parts should be considered as waste or not – some stakeholders opposed, and some supported the waste status. However, at the end, it is the city officers that control the matter and they needed to decide how to proceed with it. I cannot go through all the matters the authorities needed to consider in order to clarify the issue but in brief, the hardest part was to find a balance between environmental protection and excessive (too heavy) bureaucracy. Eventually the authorities were able to clarify their policies so that, in Finland, reused components are not considered as waste when certain pre-requisites are fulfilled. At the time of writing this blog, we’ve also received an official decision that ReCreate elements are not considered as waste. This is a huge development step in the Finnish industry towards circularity.

(2) Another matter the cities regulate is the product approval of reused building components. Unlike new products, the CE (conformité européenne) mark does not apply to reused products. In Finland, the products are approved as part of a so called ‘building site approval process’ that is regulated by the municipal building supervisors. There is no prior experience of the approval process. Consequently, the situation is now very similar to the aforementioned case: city authorities must again develop practices and policies that ensure that essential technical requirements are met when reusing components but are not too burdensome for practitioners to comply with. As I write this blog, we are in the process of discussing these practices with the authorities.

Role 2: creating needed incentives for companies for CE development.

Cities are not only passively enabling the circular transformation, but they can – and they must – actively initiate the change, too. Indeed, me and my colleagues have received feedback from multiple companies stating that due to early stage of the circular development, the industry cannot move to circularity solely with the help of market drivers and market logic. The companies emphasized the need for public initiatives that create incentives for circular development. Cities have at their disposal policy instrument that can create this market push. The most notable instruments are (1) public procurements and (2) plot handovers.

(1) During the project, we have had multiple meetings and workshops with the leaders of the city so that Tampere could incorporate reuse to future procurements and building projects. Sooner or later, reuse of building components will break through to public procurements and when it does, it will have a significant impact on the market.

(2) Another policy instrument that can initiate change is the plot handover process. In Finland, municipalities are the biggest landowners in urban areas. Traditionally, sustainability or circularity goals have not been part of the handover processes. However, in 2022 the City of Tampere initiated an all-time first circular plot competition. It was a success with nearly 20 building proposals and applications and received a lot of positive attention in general as well as in professional media. Many cities got inspired and wanted to repeat the circular competition. What we decided to do with my colleagues was to launch a working group, the goal of which was to create upgraded and unified circular criteria for the municipalities. Around 30 experts worked on the criteria for a year, and after receiving feedback in different workshops and seminars, we were able publicize the criteria at the beginning of this year. Now, we are keen to see the impact that the criteria will create when the cities are starting to include them to their plot handovers and competitions.

All in all, while this blog is not an exhaustive list of all the role the cities have in the circular transformation, I do hope that I was able make the case that cities are one of the major players enabling the transition. Indeed, for me personally, it is very difficult to see how the industry could make the transition to the circular economy on a large scale if the cities are not developing public policies and processes to promote circularity.

by ReCreate project

June 12, 2024

In June 2024, the ReCreate project reached significant milestones with two pivotal meetings held in Zagreb, Croatia. Hosted by GBC Croatia, these gatherings brought together partners, and experts to discuss progress, share insights, and plan future actions in our mission to revolutionize the construction industry through sustainable practices.

Consortium Meeting: 5th June 2024

The consortium meeting on the 5th of June was a vibrant assembly of all project partners. The event provided a platform for members to review the project’s achievements, address challenges, and align on upcoming objectives.

Highlights of the consortium meeting included:

Project Progress Updates: Each partner presented detailed updates on their contributions and advancements, showcasing the collective progress made since the last gathering. The emphasis was on the general status of the project management, communication and dissemination activities, and the status of the each project pilot.
Technical Discussions: In-depth discussions were held on the latest innovations in reusing precast concrete elements, highlighting technical challenges and solutions of each project pilot in Sweden, Finland, The Netherlands, and Germany.
Collaborative Workshop: Interactive workshop fostered collaboration among partners, focusing on differences, as well as advantages and disadvantages in centralized and decentralized pilot approaches.
Future Planning: During the meeting, partners outlined the next phases of the project, setting clear goals and timelines to ensure continued momentum and success.

Review Meeting: 7th June 2024

Following the consortium meeting, the review meeting on the 7th of June brought together WP leaders and external reviewers. This critical session aimed to evaluate the project’s progress against its objectives and deliverables.

Key aspects of the review meeting included:

An assessment of the project’s achievements to date, including a detailed examination of technical milestones and deliverables.
External reviewer Helena Granados Menéndez provided valuable feedback, highlighting strengths and offering recommendations for improvement to ensure the project’s success.
Discussions focused on the broader impact of the project on the construction industry and sustainability practices, emphasizing the importance of innovative solutions in real-world applications.
The meeting concluded with a clear roadmap for the upcoming months, emphasizing continued collaboration, innovation, and dissemination of results.

Both meetings were instrumental in driving the ReCreate project forward, reinforcing the commitment of all partners to transforming the construction industry through sustainable practices. We look forward to the next phases of the project with renewed energy and focus.

Stay tuned for more updates on our journey towards more sustainable future in construction.

by ReCreate project

May 17, 2024

Tove Malmqvist Stigell, Senior Researcher and Docent, KTH Royal Institute of Technology

A transition towards a more circular economy is currently lined up by multiple ongoing policy processes, not least within the EU Green Deal. One novel regulatory development already in effect in a few European countries is mandatory climate declarations and limit values on GHG emissions for buildings. What are these regulations and how do they connect to the re-use of precast concrete elements?

After several decades of development of LCA (Life cycle assessment) methodology for buildings aiming at guiding low-impact design in a life cycle perspective, a raised interest for building LCA has been seen during the latest years. Not least insights on the significance of embodied greenhouse gas emissions in buildings, has led to LCA-based regulations being introduced in several European countries. These require mandatory climate declarations of, so far primarily, new-build projects, and some of them also require building projects to display emissions below a set limit value. Such a climate declaration is a quantitative assessment of life-cycle related greenhouse gas emissions (GHG) of the building that the developer has to perform and hand in to the authority. Countries such as France, Sweden, Denmark and Norway already have such regulations in effect since 2022-2023. In France and Denmark limit values for these emissions are part of the regulation. Such limit values are represented by a set number of kg CO2-equivalents per floor area or per floor area and year, which can be tightened over the years to support further GHG emission reduction. Such limit values are also planned to be introduced in the coming years in Sweden and Finland. The Netherlands introduced a more comprehensive LCA-based declaration with limit value already in 2017. At EU level, the recast of the EPBD (Energy performance of buildings directive) requires a mandatory climate declaration for new-build from 2027 for buildings over 2000 m2 and from 2030 for all buildings, and similarly the EU taxonomy stipulates such a declaration from 2023 for buildings over 5000 m2.

In the light of this type of regulatory development, the interest for developing methods to implement re-use of building components in new-build has increased much. The reason for this is that reuse of components could be one, among other strategies, to ensure low-carbon designs and to comply with tougher limit values in similar regulations. This since re-used components in general have lower environmental impact than virgin ones. To incentivize such strategies further, the Swedish regulation, as an example, makes it possible for a developer to use re-used products “for free”, that is count them as zero impact in the stipulated climate declaration. When setting up the mandatory climate declaration, the Swedish regulation requires a developer to make us of generic data from the national climate data base of Boverket unless EPD´s (environmental product declaration) exist and are used (and also verified that these products were procured to the building at stake). Re–used construction products in Boverkets database are however currently allocated zero GHG emissions, thus incentivizing reused products in new building design. This is naturally a simplification for to create an incentive, but since EPD´s on re-used building components are still extremely rare it would in the current situation not benefit re-use of precast concrete elements to require more detailed information on e.g the emissions of the reconditioning processes. Meanwhile, this type of information is currently built up in the ReCreate project based on the demonstrators in the project.

A central issue of significance in the design of building LCA studies, including the method of LCA-based regulations, is the coverage of processes, that is the system boundaries for the assessments. It is often necessary to omit certain processes due to lack of data or to focus the assessments on known hot-spots. When these types of assessments now enter regulation, different countries take slightly different approaches to the choice of system boundaries which has led to discussions regarding how they then incentivize, or not, certain low-carbon strategies such as circular solutions. For example, the Swedish regulation focus the production and construction stage impacts, that is the embodied GHG emissions of modules A1-A5, according to the European standard EN 15978. In a life cycle perspective, these emissions constitute a significant, and earlier non-regulated, hot-spot. These emissions can also be verified by the completion of a building project, compared to emissions associated with the use and end-of-life stages of buildings. Principally, one could argue that such a more narrow system boundary increase the incentives for re-use of precast concrete elements since the emissions of modules A1-A5 in contemporary construction of buildings are much dominated by the materials of the structure. If implementing more of a whole-life system boundary, as for example is planned for in Finland, the proportional impact of modules A1-A5 will be less, which might reduce the incentivizing effect of re-using building components.

A well-known obstacle to reuse today is the difficulty, and thus the high costs, of dismantling buildings for re–use of elements and components with a viable service life left. This is a question that often comes up in connection to building LCA, with the idea that including the end-of-life (module C) and benefits and loads beyond the system boundary (module D) in the assessment system boundary would incentivize measures taken for design for re-use, including design for disassembly (DfD). However, end-of-life emissions associated with pre-cast concrete elements are much lower compared to emissions associated with the production stages (modules A1-A3) of contemporary construction in the European context, and it may thus be questioned to what extent it´s inclusion could have an incentivizing effect.

An aim with module D is to give room for displaying future potential benefits in form of emission savings due to e.g reuse of components in new constructions, to be reported separately according to the EN 15978 standard. It should be noted that module D highlights potential future savings, the extent of which depend on the future handling of the components, which is hard to predict. The prospects for future re-use improve with DfD implemented, but the calculation of module D is not linked to whether such design strategies were implemented or not. Finally, one needs to remember that both module C and D deals with assessment of potential emissions in a distant future, thus their assessment becomes very uncertain. Normally, these assessments reflect today´s technology, but an increasing number of voices promote that decarbonization scenarios should be applied in similar long-term assessments. If so, the significance of module C and D also decrease.

The proposed Finnish regulation is an example of a more comprehensive system boundary. It for example introduces the “carbon handprint” which more or less reflect an assessment of module D to, in quantitative terms, visualize potential future benefits of re-using the components of the studied building along with other potential benefits of implemented design strategies.

So to sum up, the emerging climate declaration regulations in various European countries do create new incentives to apply re-use of prefabricated concrete elements in today´s new-build. However, to for increased implementation of DfD strategies in today´s new-build for improving prospects for future re-use, these types of regulation do not provide direct and clear incentives. Instead, complementary steering mechanisms might be needed to promote DfD strategies.

Resources:

Boverket climate database in Sweden: https://www.boverket.se/sv/klimatdeklaration/klimatdatabas/

Finnish emissions database for construction: https://co2data.fi/rakentaminen/#en

Example of proposed ongoing regulatory development: the next steps proposed for the Swedish climate declaration regulation: https://www.boverket.se/en/start/publications/publications/2023/limit-values-for-climate-impact-from-buildings/#:~:text=Limit%20values%20can%20be%20introduced,on%20climate%20declarations%20for%20buildings

by ReCreate project

March 15, 2024

Inari Weijo, business development manager (refurbishment), Ramboll Finland

During my master’s thesis work over 15 years ago, I familiarised myself with precast production and its history in Finland. After that, precast concrete has been playing a role in one way or another in my work career. Many projects have involved either repairing precast concrete buildings or building new ones. Since the 1970’s, precast concrete production has formed a significant part of the Finnish construction sector. The systematic and ‘simple’ method provided a standardized way to build, and it quickly became very widespread. The precast concrete system has been criticized for producing a unified stock of buildings, reducing versatility in urban environment and suppressing designers’ creativity. Since the early days, though, the technique spread to erecting ever more complex and monumental buildings. It has been foundational for providing a fast and trusted way for building construction in Finland. There are thousands and thousands of precast concrete buildings here, and some of them are already slated for demolition. A part of the buildings suffers from degradation, but many are just mislocated from today’s point of view.

Figure 1. Finnish deconstruction pilot in Tampere, building vacated before the deconstruction of elements for reuse.

I believe that technical know-how is essential for creativity and enables responsible and sustainable construction. We must be more aware of our decisions’ environmental impacts when building new. Architects’ and engineers’ creativity is ever more challenged as we must prioritize sustainability values. Knowing the technical limitations and possibilities is crucial, so that creativity can be unleashed in the right place at the right time, and adverse uncertainties can be eliminated. Building new is inevitable in the future too, but we need to redefine ‘new’. We must apply regenerative thinking, create net positive solutions and aim for more ambitious circularity. The actions we undertake should have a positive impact on nature and the environment so that instead of consuming it, they restore and revive it. This is a leading value for Ramboll.

Figure 2. Regenerative approach to construction. Image source: Ramboll.

The prevalence of precast technology and the aim for a regenerative effect on environment are two leading thoughts that that drive our ambition here at Ramboll to examine and challenge the present business as usual in the construction sector. The headline’s statement inspires me and my colleagues at Ramboll Finland when we seek to find alternative ways to utilize what already exists. The built environment is a bank of building parts that has technically perfectly fine components stocked in it, preserved intact inside buildings. Only processes and systems to utilize them effectively are needed. I sometimes face people itemising reasons and obstacles why reusing building parts is way too difficult. I believe this pessimistic attitude may well up from the insecurity that follows from the building sector changing dramatically. There may also be a disbelief whether the huge leap, which is necessary, can be taken. Some of the items that the sceptics list are well known, some are relevant, and some are just fictional. We need to keep solving them one by one, showcasing with real-life projects that this is possible and acquire more experience to narrow down the gaping hole between the ‘old’ and the ‘new’ way of building.

An important milestone has been reached when the Finnish cluster finished the deconstruction of the pilot building in Tampere this autumn. We succeeded to reclaim several hundred hollow-core slabs, columns and beams intact, ready for use on next building site. It’s been encouraging to gain good test results, both before deconstruction, through a condition investigation, and after deconstruction, as some of the deconstructed elements have been load tested. All has been well from an engineer’s perspective! Now, the reclaimed building parts are being fitted into prospective new building projects. The search for the new building site has not been stalled because of any technical issues but rather by the currently poor market situation.

That final issue to solve – an important one indeed – is the business model that can support reuse. A circular business needs more collaboration among all the players in the field. Technically we are ready to say ‘yes’ to reusing precast concrete elements!

Figure 3. Reclaimed hollow-core slab, deconstructed from the donor building in Tampere.

by ReCreate project

February 28, 2024

José Hernández Vargas

Architect and PhD student at KTH Royal Institute of Technology

A precondition for reusing precast elements is a correct understanding of the underlying logic of different building systems and the structural interactions between concrete elements. The analysis of existing precast systems starts with a thorough examination across multiple scales, as building layouts, individual elements and their connections are interdependent.

During ReCreate, several precast concrete systems have been identified and studied. While specific pre-demolition auditing and quality control are critical steps towards reusing concrete elements, this ordering of precast elements operates at an earlier and more abstract level, providing a knowledge base for known precast systems that may apply to multiple instances. This task attempts to provide an overview and develop guidelines for the further classification and digitalisation of precast elements as potential material for reuse. Moreover, the information gathered can serve as methodological guidelines for other systems that may differ from the studied cases but follow the same core principles.

When examining technical drawings from historical precast systems it is important to identify patterns that reveal the systematic ordering of the elements. This initial step involves identifying the underlying measurement system from the axes of the building, from which standard layouts can be inferred in discrete modules. Strict repetition patterns can often be found, especially in residential buildings, where building blocks are constituted by the repetition of a building module defined by a staircase. Similarly, this building module can be divided into residential units corresponding to the individual flats on each floor. Each unit defines in turn a defined arrangement of precast elements that can be precisely estimated for each building.

Thus, architectural and structural knowledge of precast buildings is essential for accurately estimating the building stock and potential for reuse of precast buildings. Given the economies of scale involved in this kind of building, the goal of this step is to build a knowledge base to establish workflows for the ordering and analysis of potential donor buildings for reuse.

Building scale

At the building scale, the analysis centres on the identification and classification of precast structures by structural principles and different building types. Precast buildings can be found in all sorts of applications. Yet, despite the wide range of structural solutions they predominantly follow a limited set of basic structural systems. The most prevalent structural frameworks for precast concrete include the portal-frame, skeletal structures, and wall-frame structures. Structural systems for arranging precast structural systems are closely linked to the building types they serve, responding to the intended program’s requirements. For example, portal-frame structures are most suitable for industrial buildings that require large open spaces. Conversely, for residential buildings wall-frame structures are more often the most cost-effective solution as load-bearing walls also separate living spaces. Beyond buildings completely built out of precast components, specialised subsystems can be found for facades, floors and roofs in combination with other structural systems.

System Skarne 66 (Sweden) and their main structural components form the original technical drawings (left) and as a digital 3D model (right)

Component scale

At the scale of individual precast elements, the foremost classification derives from grouping them by their structural role in the structure, i.e., as walls, columns, slabs, roofs, beams, foundations, and stairs that constitute the structure of the building. These categories are based on the Industry Foundation Classes (IFC) Standard (ISO16739-1), which provides a consistent framework for describing elements within the construction industry. These groups can be understood and modelled as variations of the same parametric object, akin to a family of building components. This process is key for building a comprehensive database of precast elements contained in each building.

To further understand the arrangement of elements that constitute a system, the overall dimensions of each element can be plotted to reveal the dispersion of distinct types within the system. In this example, all the elements are aligned in Cartesian space to define the largest dimension on each axis. This method allows the creation of a ‘fingerprint’ of each building, that shows a concise overview of the dispersion of element types and the individual quantities involved. Alignments resulting from common features such as floor heights and standard modules, can also be observed.

Comparison of the ‘fingerprint’ tool showing the types of elements used in System Skarne 66 (Sweden) and BES (Finland). Dot size indicates the number of elements of each type whereas colour corresponds to the main component categories.

Connector scale

At the connector scale, the different relationships between concrete elements can be related to force transfers and security features to ensure the correct and reliable transmission of forces. Connectors are key to ensuring structural integrity by managing structural loads while accommodating additional stresses and strains that arise from thermal movements, residual loads, seismic loads, and fire exposure, among others. A key aspect for evaluating the connectors is the assessment of the alternatives for disassembly and possibly reusing the connector. Analysing precast buildings at the connector scale allows the identification of the compatibility of precast elements across multiple systems from the analysis and comparison of structural details.

Ordering precast systems across these three scales provides a comprehensive picture of how precast systems are conceived, manufactured, and assembled. This knowledge is instrumental for understanding the possibilities that these elements offer for the next building lifecycle. This ordering will serve as the basis for classifying different precast systems into taxonomies and for the digitalisation of existing precast stocks as material for reuse in future projects.

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