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Featuring bio-based building materials made from renewable resources like wood, hemp, straw, and cellulose.
As architects and construction professionals move away from fossil-based materials, marine biobased materials—derived from seaweed, eelgrass, algae, shells, and other aquatic biomass—are emerging as compelling alternatives. These rapidly renewable resources present opportunities for reducing embodied carbon, enhancing indoor health, and fostering circular material cycles.
This article combines findings from recent industry case studies and a technical playbook developed by Arup and the Nordic Blue Building Alliance to outline the environmental potential, technical performance, and integration pathways for marine biobased materials in the built environment.
Marine materials such as eelgrass, algae, and mussel shells are not only rapidly renewable but also offer unique ecological and technical properties. Seaweed and eelgrass, for example, sequester carbon and contribute to healthier marine ecosystems, while their use in insulation and cladding revives vernacular construction techniques adapted for modern low-carbon design. Eelgrass panels, like those produced by Søuld, have been used in acoustic applications that also meet stringent indoor air quality standards, making them well-suited to schools, offices, and housing.
Similarly, seaweed-derived bioplastics and binders are being explored for wall elements, insulation composites, and biodegradable interior surfaces. These materials are often compostable and nontoxic, which aligns well with emerging health and circularity criteria in green building certifications. In Denmark, Møn Tang has commercialised insulation products using naturally dried beach-cast eelgrass, offering a thermally efficient and low-embodied carbon solution that draws from traditional Danish construction.
While algae's use in structural components is still developing, it is already finding innovative applications in products like Prometheus Materials' algae-based bricks. These are made by combining microalgae with mineral aggregates to create a biocement, avoiding the CO₂-intensive calcination process of traditional concrete. Such innovations are opening new frontiers in marine-based structural materials.
Mussel and oyster shells, once discarded as food waste, are increasingly seen as valuable aggregates in tile manufacturing and bio-concrete. For example, ReefCircular in Denmark has created a 3D-printable concrete using crushed oyster shells and marine-derived binders. This circular use not only diverts waste but also substitutes mined limestone, reducing the material's overall environmental load.
Even reed, historically used for thatching, is making a return in contemporary architecture. Danish studios like Dorte Mandrup and Henning Larsen have embraced reed in roofing and cladding, valuing its breathability, fire performance, and tactile qualities. When sourced responsibly, reed harvesting can also help maintain wetland biodiversity, as seen in marsh management practices across Nordic countries.
These materials each bring distinct benefits to architectural practice: eelgrass for acoustic and fire-resistant interiors; seaweed for biodegradable composites and thermal panels; algae for inks, biopolymers and experimental concrete; shells for structural fillers and decorative finishes; and reed for its low-tech, carbon-sequestering potential.
The technical profiles of marine materials demand a nuanced approach to integration. Some materials, like eelgrass and reed, have established durability and fire resistance, especially in interior applications. Others, such as algae-based bioplastics, show great promise but may require additional performance data before widespread structural use.
Marine materials are typically low in VOCs and often biodegradable. However, end-of-life scenarios must be planned carefully: whether these materials are to be composted, recycled, or incinerated safely. Where biogenic carbon is sequestered in the material, disposal routes can influence net climate impact.
Responsible sourcing is crucial. Many of these materials—particularly shells and eelgrass—are sourced from waste streams or beach-cast biomass. This minimises extraction impacts and enhances circularity. In contrast, wild harvesting of seaweed or shellfish should be avoided unless clear sustainability measures are in place. The Nordic Blue Building Alliance emphasises these lifecycle considerations in its guidelines.
Recent research projects further illustrate the versatility of marine-derived materials. The Eco Hanok Project in South Korea demonstrated how crushed oyster shells can be transformed into low-carbon bricks for use in non-load-bearing applications. Led by BC Materials in collaboration with local institutions, the project recycled seashell waste into unfired masonry units, proving that marine byproducts can be structurally and aesthetically integrated into architectural prototypes.
In parallel, researchers at the Technical University of Munich are investigating carbon fibre production from algae as a substitute for steel. Their work shows how algae cultivation and biotransformation can yield carbon-negative materials suitable for high-performance construction. These fibres, when embedded in composite materials, offer strength comparable to steel but with significantly lower weight and emissions.Real-world applications demonstrate the architectural relevance of marine materials. Søuld’s acoustic panels have been installed in educational and cultural settings, offering Class B-C absorption ratings with biogenic carbon benefits. Møn Tang’s eelgrass insulation has been used in housing projects that celebrate local material culture while meeting contemporary thermal regulations.
Kathryn Larsen’s experimental seaweed cladding reinterprets Læsø’s vernacular typologies using contemporary fabrication techniques, blending heritage with innovation. At the Vadehavscentret by Dorte Mandrup, reed has been reintroduced in the building envelope not just for performance, but to echo the surrounding coastal landscape, blending material culture with ecological sensitivity.
More industrial applications are represented by Prometheus Materials and ReefCircular, who are working to scale marine-based concrete alternatives using algae and oyster shells respectively. Their work could redefine structural systems in low-rise construction. Agoprene, another notable innovation, has developed a kelp-based foam alternative to petroleum-based foams, aimed at insulation and cushioning applications within the built environment.
These case studies highlight a shift from niche, decorative or temporary uses to robust, scalable systems supporting long-term architectural needs. They also demonstrate how marine materials can enhance indoor health, reduce embodied emissions, and foster material narratives rooted in local ecologies.
Marine biobased materials embody a new material paradigm—one that connects carbon cycles, ecological restoration, and cultural continuity. They offer more than technical performance; they bring narrative, place-based identity, and circular potential into the design process.
As the market matures and guidance becomes clearer, architects have the opportunity to build not just by the sea, but with it—crafting spaces that regenerate ecosystems and redefine what it means to build with care.
To support further exploration and specification, Arup’s guide to biobased materials offers a detailed look into the environmental performance and use cases of these materials in the built environment. You can find the guide here.
And if you’re looking for a place to start, revalu’s Biobased material collection offers a curated overview of bio-based products ready for architectural application. You can find it here.
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