Design Indaba Global Graduate, Kathryn Larsen presented a quietly radical proposition: The future of sustainable architecture may already exist in the past. During her talk at Design Indaba’s 25th anniversary, Larsen shared her work that centres on reviving eelgrass, a form of seaweed as a viable building material, drawing from centuries-old techniques once used on the Danish island of Læsø.
Larsen’s approach is rooted in rediscovery. Historically, eelgrass was used for roofing, insulation and construction due to its durability, rot resistance and natural insulating properties. Today, however, it is largely discarded as waste with thousands of tonnes thrown away each year. Her project, Seaweed Thatch Reimagined, translates this vernacular method into a contemporary system. By developing prefabricated thatch seaweed panels for roofs and facades, she demonstrates how ancient knowledge can be adapted for modern construction processes merging craft with industrial scalability. Her work extends beyond architecture into product design, including experiments with kelp-based materials for furniture and fashion, reinforcing a circular, bio-based approach to design. Larsen’s talk provides a shift in perspective: the future of design may lie in remembering rather than inventing.
Watch the full Design Indaba talk here.
