Iceland’s first hempcrete building was completed in November. The project, inspired by Japanese tea houses, uses local materials and emphasises natural, eco-friendly building practices, including the innovative use of seaweed.
In November, Iceland’s first building made from hempcrete was completed. The idea for the building – referred to as the BioBuilding and created by Anna Karlsdóttir and Jan Dobrowolski of Lúdika Architects – was born in 2020. It is located in Grímsnes in South Iceland.
“The idea came to us when we moved back from London to Iceland in the fall of 2020. Upon hearing that the import and cultivation of industrial hemp seeds had been legalised earlier that year, we saw a great opportunity – not just for the construction industry but also for agriculture and other innovations,” Anna told Iceland Review.
The project received grants from the Design Fund, the Technology Development and Climate Funds of Rannís, the Askur Civil Engineering Research Fund, the Entrepreneurial Fund of Íslandsbanki Bank (Frumkvöðlasjóður), and the Women’s Loan Guarantee Fund (Svanni).
As noted by Anna, it is estimated that the global construction industry is responsible for about 40% of total carbon emissions. “This is where hemp plays a significant role,” Anna explained. “Industrial hemp sequesters 9-15 tonnes of carbon per hectare annually, which is up to twice as much as trees. Moreover, hempcrete captures carbon from the atmosphere during its drying process, making it a carbon-negative building material.” (While hemp may absorb carbon at a faster rate per hectare in the short term, trees can store larger amounts of carbon over a longer period.)
The composition of hempcrete is relatively simple: a mixture of hemp hurds (shives), lime, and water. Hempcrete is free from toxins and provides insulation, is resistant to mould and fire, is soundproof, and can be broken down and used as fertiliser at the end of its lifecycle.
Inspired by Japanese tea houses
Given the size and height limitations of the BioBuilding project, along with the project’s ethos, Lúdika drew inspiration from the philosophy of Japanese tea houses, which emphasise craftsmanship, are often made of natural materials, and are very small.
The prototype hempcrete house is only 15 square metres, using local materials as much as possible for foundations, structural frames, cladding, and seaweed screens. Construction began in the spring of this year and finished in November.
“We teamed up with young journeymen (wandergesellen) from Germany who spent the summer with us building the house. They were skilled craftsmen, and we had many discussions about the construction industry here and in Europe, different solutions, and what the future holds. It was a truly enriching collaboration,” Jan remarked.
Early next year, instruments will be installed in the building to record its performance and provide a concrete assessment of how hempcrete withstands Icelandic weather.
“We have full faith in hempcrete as a building material in Iceland; it’s a solution that can be scaled up. Our vision is a more environmentally-friendly construction industry and healthier houses. Hempcrete houses are considered among the healthiest buildings available, as the walls are made of natural materials that breathe. They maintain good temperature and humidity levels indoors,” Jan explained.
Lúdika believes that the BioBuilding experiment is just a small step towards a more sustainable future.
“A fundamental change is needed in how we, as a society, approach buildings and the materials used in them. What do we use for construction, repairs, and fittings — where does it come from, what is it made of, and how is it composed? Our project is just one example of how natural building materials can be used today; the possibilities are many,” Jan observed.
Seaweed: the hemp of the sea
Serving not only as a testbed for hempcrete, the project also saw Lúdika, in collaboration with Alberte Bojesen, experimenting with the use of Icelandic seaweed as screens.
“Seaweed is, in some sense, the hemp of the ocean, as it absorbs a substantial amount of carbon from the atmosphere and grows rapidly like hemp. It is abundant along Iceland’s shores, so we were excited to explore its use as a building material,” Anna stated.
Timber frames were built and covered with screens made from seaweed. The frames were attached inside the windows of the house, capturing sunlight and providing privacy.
As noted by Anna and Jan, the BioBuilding emphasises craftsmanship and the understanding of the building material, its composition, and properties. Lúdika is looking towards a future where not all building materials need to be imported but where local materials can be used.