Can Construction Adopt Bio-Based Materials?

It is well established that addressing climate change requires decarbonising of the construction industry. A critical aspect of this is reducing embodied carbon in new structures.

One emerging solution to this would be the wide scale adoption of bio-based construction materials. These materials come from biological sources (such as plants, animals and microorganisms) and have significantly lower embodied carbon compared to traditional fossil fuel-based materials such as concrete and steel.

However, despite their benefits, building with bio-based materials remains challenging in European countries due to strict regulations, limited availability, and widespread lack of knowledge.

So, what can we, engineers and planners, do to overcome this?

Earlier this year, participants in our Urban C:lab programme discussed this problem with external collaborators and industry experts to learn from their experiences. Joanna Hedley-Smith, Oliver Lerch and Oliver Stainton, members of the EU cohort, have summarised the following key themes.

Adapting material performance expectations

An important driver of which materials are used in construction relates to our material performance expectations. As designers, we are accustomed to the uniformity of man-made materials in terms of material properties, how they are handled on site, and the lack of significant maintenance over their lifetime.

But should we hold bio-based materials to the same standards?

Perhaps this would be inappropriate due to the inherent variability of natural materials compared to manufactured ones, meaning both our expectations of such materials and where we apply them should be carefully considered. They cannot simply be swapped like for like with conventional construction materials, Dan Maskell, senior lecturer at the Department for Architecture & Civil Engineering, University of Bath argued. It shouldn’t be a surprise to perform maintenance, or renew components of a building after their design life has passed. Instead, we should focus on accepting that the material has met the original expectations and then repair it to extend its life.

There was also consensus that market uptake of sustainable alternatives would be faster if the materials had undergone some level of standardisation rather than remaining entirely natural. Felix Wierschbitzki from raumlaborberlin and SLAB pointed out that handling of these materials on site would then be more similar to conventional ones, and significant retraining of labour forces would not be required.

Regarding material properties and structural performance, Katrine Juul, lead sustainability architect at Henning Larsen in Copenhagen, explained that she has started to see a general shift towards the acceptance of timber as an alternative to concrete in Denmark. However, there is still an expectation for the structural form of a building to remain the same as in a concrete structure, where the same structural spans should be achieved. In addition, it is essential to question whether, for example, tall timber buildings really do contribute to a more eco-friendly built environment, as ‘sustainable’ materials are always context dependent, as mentioned by Kika Brockstedt, co-founder of revalu.

The expectations of the acoustic performance of buildings were also called into question. To meet acoustic requirements, the conventional solution is to add additional mass to slabs and walls, which increases the building’s embodied carbon of a building, somewhat unnecessarily. Duncan Horswill of Ramboll explained that if we can reduce acoustic expectations in the first place, there would be a great opportunity to save carbon.

Supply and demand

Currently regarded as a niche, small-scale market, it could be difficult to meet the demand of large construction sites with the current volume of bio-based construction materials that are being produced. David Trujillo of Atelier One and the University of Coventry mentioned that even if we started by just specifying all windows and door frames to come from bio-based sources, on a country scale, this would be a huge amount.

But how can production be significantly increased?

Klaas De Ryke of Bollinger & Grohmann/University of Architecture, Versailles, The Bartlett, University College London, suggested that large-scale manufacturers of conventional materials could be the key. As the industry strives to decarbonise, there will be more demand for manufacturers to diversify and reduce the embodied carbon of their product portfolio. These companies are well established, have the resources, technical knowledge and experience to get building products certified and mass produce them, and are, therefore, in a crucial position to support small-scale manufacturers of alternative products to do the same.

Karianne Kraaijestein, from the Built by Nature prize explained that she is already seeing the demand for bio-based materials rapidly increase. This year saw the first edition of the prize, which is intended to explore the potential of bio-based materials on a global scale and to address the need for transformation within the sector. 297 applications were received from more than 50 countries, indicating that this is not just a regional problem, so perhaps the supply issue is not quite as daunting as we once assumed?

The predicted exponential population growth of urban areas in African countries could be an excellent opportunity to demonstrate the suitability of bio-based materials in sustainable construction. Nyomi Roswell explained that historically, the built environment of Western countries has been regarded as a status symbol in developing counties, with an aspiration to emulate their architectural styles. It is therefore important that in the future development of urban areas in Africa, any inspiration taken from the western world focuses on the most innovative, sustainable solutions, to ensure the associated environmental impacts are as low as possible.

Detailing is critical and changing the stigma

Despite the negative reputation of bio-based construction materials, particularly concerning durability and fire safety, this perception is often misguided, according to Dan Maskell. An essential factor to consider when working with innovative construction materials is the importance of detailing and its thoroughness. Mistakes in the detailing process are frequently responsible for the issues listed above, Matthias Oppe from knippershelbig pointed out. Therefore, these problems should not be solely attributed to the novel material but rather to human error in detailing.

For centuries, natural and traditional building materials have endured, with many examples of structures still existing today. So perhaps it’s time to forget what we have learnt in the past 50 years, and instead learn from the previous 500 years, combined with modern construction practices, argued Katrine Juul.

Insurance process and profit margins

Thanks to Funké Adeosun, global transition solutions director at Allianz Commerical, we were able to delve deeper into the topic of insurance when implementing ‘novel’ building materials. A key driver behind being able to insure bio-based materials (or any new material) is the volume of data available, in particular when it comes to material failure modes. A lack of enough reliable data prevents an accurate prediction and understanding of all failure modes, which then limits the scope and availability of insurances. This affects the overall confidence in a material, as there may not be a complete understanding of the risks involved with its use. This highlights the need for further research, testing and, crucially, monitoring of building projects that have used bio-based materials.

So how can these materials be employed on construction projects today?

This relies on the alignment between the client and regulatory authorities. When these materials lack existing regulations, a unique approval procedure involving prototyping and rigorous testing is usually required. Once the material has been implemented in a project, ongoing monitoring and maintenance are typically necessary for several years post-completion, something that Patrick Teuffel of Circular Structural Design and the SRH Berlin School of Technology experienced during the construction of fibre-reinforced polymer footbridges in Almere in 2022 and Ulm in 2024.

Additionally, there appears to be a lack of interest among construction companies in investing in research for novel construction materials. According to Manfred Curbach, director at the Institute for Massivbau, Technische Universität Dresden, companies often face limited profit margins. Consequently, this financial limitation hinders their ability to allocate resources toward exploring new construction materials.

The Danish effect

Throughout the European region and the world, carbon targets and roadmaps are being introduced to drive down the construction sector’s impact on the environment. Denmark is the first EU country to affect a large change on a national level. It recently introduced more stringent carbon targets for both embodied carbon and energy over time, reducing from 12 in 2024 to 7,5kgCO₂e/m²/year by 2030.

Working in Denmark, both Katrine Juul and Duncan Horswill have already noticed an increase in interest and motivation in using alternative solutions to ensure the targets can be met. Similarly, a change in focus has taken place in investment portfolios for Danish institutions, such as pension companies. Duncan explained that these companies now have an increased interest in investing in healthy and sustainable buildings, following the introduction of the new regulations. So perhaps the key to making change in the industry is the creation of regulations.

Housing is the first step to adoption

Paul Rogers of Buro Happold mentioned that with an ever-increasing demand for housing in cities, the benefits of bio-based materials could provide a driver for creating more attractive properties and investments. The health and wellbeing benefits associated with bio-based materials could be quantified and measured, then lead the design requirements of new buildings, alongside energy usage and environmental impact.

As a starting point, there could be an initial focus on implementing bio-based materials in non-load-bearing components, such as partition walls, floor build-ups, insulation, or façade elements, said Manfred Curbach, as these will be viewed as the lowest risk elements. Following this, a staggered implementation of these materials could be a key to ensure their success, allowing for the demand to gradually increase without overburdening the supply, as well as allowing for insurance and regulatory authorities to keep up, as mentioned by both David Trujillo and Funké Adeosun.

Conclusion

These insightful conversations have shown us that there is no single solution to the problem at hand. It will always be a combination of implementing a ‘material first’ approach and assessing what is actually needed for your project. Overcoming the hurdles mentioned above will not be a simple process, but so long as the demand is there and growing, we will see results, such as those that are already tangible following the implementation of the Danish embodied carbon targets.

Across Buro Happold, involvement in projects implementing natural building materials is growing, such as the Nest House, recently completed by the Copenhagen team, along with our C:lab project.