As the first person in the UK to build a home using EcoCocon’s straw panel Passive House system, George Mikurcik, Technical Specification Architect at Ecological Building Systems, discusses why he believes straw is a hugely underrated insulation material.
I first came across straw construction while studying at the Slovak Technical University in Bratislava in the late 1990s. Although straw is not a new material in construction, it was many years later, when I first saw it being engineered properly – prefabricated, tested, certified and ready to compete on the same terms as any conventional timber frame build-up.
I was introduced to EcoCocon, a Lithuanian manufacturer which produced prefabricated timber frame panels insulated with compressed straw, over 10 years ago by a friend who worked with them. Here was a natural material that could achieve Passivhaus-level performance with full certification behind it that provided a genuine alternative to traditional brick and block construction. Having spent nearly 19 years at sustainable architecture practice, Architype, much of it delivering Passivhaus buildings from private homes to large-scale schools, I understood what the combination of performance and buildability meant in practice.
Airtightness, continuous insulation and thermal bridge-free detailing are the essential principles of Passivhaus design. EcoCocon’s wall panel system offers all three. With EcoCocon, straw itself is compressed in the factory under controlled conditions, eliminating the gaps and weak spots that cause cold walls and condensation in poorly built timber frame structures. Panels are screw-fixed tightly together, wrapped in an airtight, vapour-open breather membrane and typically finished with an outer layer of wood fibre insulation. The result is a wall system that behaves like a breathable jacket – draughts are kept out, moisture is allowed to escape and the fabric stays dry. A typical 400mm build-up achieves a U-value around 0.13 W/m2K, which is comfortably within Passivhaus range.
I have tested this principle in the most direct way possible by building my own EcoCocon home in Herefordshire. The external walls were erected in three days, the roof took 2-3 weeks, which meant the whole building was weathertight within weeks. Nine years on, I can report that high insulation levels and airtightness have reduced heating and cooling demand by around 80% compared with standard homes built to building regulations. The house is fitted with solar PV and battery storage, which means we have a genuine zero-bills house.
For any architect or contractor looking to decarbonise their construction methods and produce more sustainable buildings, EcoCocon offers a compelling case. The panels are 98% renewable produced from locally sourced wheat straw and responsibly sourced softwood. This sequesters around 115kg of CO₂ per square metre of wall area, while remaining a Passivhaus Institute Certified Component with fully solved construction details for eliminating thermal bridging. This all means that designers and builders specifying the EcoCocon system can be assured that their buildings are likely to comply with the stringent Passivhaus performance and certification criteria. When engineered properly, straw is one of the most rigorously tested, low-carbon insulation solutions available to specifiers today – as EcoCocon is proving.
For more information on EcoCocon straw wall systems from Ecological Building Systems visit: www.ecologicalbuildingsystems.com
