The seaweed archives: A material study of seaweed as a building material and its implementation on two buildings on North Koster, Sweden

Abstract

At the beginning of April 2022, Sweden had already depleted its annual budget of the earth’s resources (Global Footprint Network, 2022). The current climate and biodiversity crisis brings new challenges to architects as thirty percent of the global energy-related carbon emissions are produced by the building industry (Basyigit et al., 2021). Facing these challenges, the need for environmentally friendly and sustainable building materials has increased significantly. This master thesis aims to offer an alternative to current conventional materials and move from carbon emission to carbon storage by focusing on an abundant, underutilized and, if harvested right, highly sustainable material: Seaweed. Seaweed, or macroalgae, is easy to grow and abundant along the Swedish coastline. It requires no land, fertilizers or fresh water and grows about thirty times faster than land-based plants. Marine plants (mainly eelgrass) have been used as a building material in the past as insulation and roofing material, and has been proven to be efficient and durable. Its natural resistance to mould and fire has allowed the material to be preserved for centuries (Widera, 2014). Although there are a few new examples of seaweed being used in architecture and design, it is still a quite underutilized material within this field. This master thesis highlights the versatility of seaweed and explores its potential use as a building material through material experiments and reference studies. As a part of this thesis, real architectural elements are proposed and tested in relation to different aspects like tactility, visual appearance and water resistance. The material experiments include bioplastics, bricks, panels and seaweed shingles serving as both interior and exterior materials. Material findings are applied to the design proposal of two buildings on the Swedish island North Koster. This site is surrounded by Kosterhavet National park, the first national marine park in Sweden and home to the most diverse marine life in the country. One of the proposed buildings contains a café and exhibition space displaying the versatility of seaweed in architecture and design. The second built structure is a floating sauna platform that can be reached by foot or kayak.