Brief
Discover how Henning Larsen Architects utilize straw and eelgrass to create a groundbreaking eco-friendly school in Denmark, dramatically reducing carbon emissions without compromising aesthetics.
Insight
Henning Larsen Architects have pioneered the use of straw and eelgrass in the construction of Feldballe School in Rønde, Denmark, significantly reducing carbon emissions without sacrificing aesthetics. The 2,700-square-foot extension features straw-insulated walls and a wood roof, resulting in approximately half the annual CO2 emissions permitted under Denmark’s building code.
With greener electricity grids in Europe, the focus has shifted towards cutting embodied carbon in construction materials. Henning Larsen developed a hierarchy of building materials based on carbon intensity, finding straw to have the best carbon absorption relative to insulation properties. This sustainable approach to construction is rooted in the use of straw bales as a low-cost, low-impact building material since the late 1800s.
The architects used highly compacted straw for insulation, framed by wood for structural support. Collaborating with a local university and EcoCocon, they tested the straw-based wall components for thermal performance and resistance to issues like mould, fire, and pests. The goal was to transition from a “hippie material” to an industrial building product.
The school was designed for possible disassembly, with components transported on a single truck and assembled on-site like Lego blocks. Eelgrass, a bio-based solution abundant in Denmark, was used for passive ventilation. Its natural salt content offers protection from mould and fire without artificial treatments, reducing toxicity.
One limitation of straw wall components is their thickness, which reduces interior square footage. However, this issue diminishes in larger buildings. The architects envision the straw-based wall system being used in warehouses or logistics facilities, replacing carbon-intensive steel and concrete and presenting significant potential for more sustainable construction.
Highlight
- The 2,700-square-foot extension features straw-insulated walls and a wood roof, resulting in approximately half the annual CO2 emissions permitted under Denmark’s building code.
- Henning Larsen developed a hierarchy of building materials based on carbon intensity, finding straw to have the best carbon absorption relative to insulation properties.
- The school was designed for possible disassembly, with components transported on a single truck and assembled on-site like Lego blocks.
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