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Materials & structure·applied

Bio-Based Insulation

Why it matters

Insulation is where a building's climate accounting gets ironic. The industry's favourite insulators, foamed plastics and mineral wools, cost serious carbon to make, offgas or shed fibres for decades, and end as unrecyclable waste. All in the name of saving energy. Bio-based insulation flips every term. Cellulose, hemp, straw, and wood fibre grow by pulling CO₂ out of the air. So a well-insulated wall becomes a small carbon vault that keeps sequestering for the building's whole life. They breathe, buffering indoor humidity instead of trapping it into mould problems. They are regional agricultural products, not petrochemical imports. And when the building's life ends, they compost instead of persisting. Same thermal physics, opposite planetary sign.

Role in 001's holistic picture

Bio-based insulation is how the Energy-Efficient Envelope earns its ecological claims twice — once by saving operational energy, once by storing embodied carbon. It pairs with timber structure and hemp-lime as the fabric of a fossil-free building, contributes the humidity-buffering "breathing" that Indoor Environmental Quality prizes, and leans local by nature. The best insulation crop is often growing in the next valley.

In the world

The working families — blown-in cellulose, hemp fibre, straw, wood-fibre board — share one discipline that separates success from folklore: install at the right density and design the assembly to dry. That discipline now runs at industrial scale. EcoCocon prefabricates load-bearing straw-and-timber wall panels — 98% renewable material, no glues. Per the company's own figures, they stand in some 400 projects and 49,000 m² of walls, reach Passive House performance, and get a house weathertight in five to seven days. Its record order to date, about 40,900 m² of straw panels for a logistics centre in Lelystad in the Netherlands, is set to be the biggest straw-panel building yet. Wood fibre has scaled the same way. STEICO runs what it calls the world's largest integrated wood-fibre insulation plant. It covers roughly 100 hectares at Czarnków in Poland, one of five production sites across its European network. It produces insulation boards, flexible mats, blown fibre and engineered timber. Straw and wood fibre not as folklore, but as precision industry.

How 001 engages with it

House 001 provides the lesson in both directions. Its insulation is loose sawdust. The price is near zero, but the choice rested on everything else it is: natural, circular, and available basically anywhere wood is worked. Years of living-lab observation delivered the verdict honestly: it settled and opened thermal gaps. Those gaps are part of the house's poor measured thermal performance. The lesson is precise, and it is not "sawdust fails". Sawdust makes two demands we did not know at the time: pack it dense, and design from day one for compensating its sag. A third remedy comes from the living lab's own method: put sensors inside the wall — temperature, ideally humidity too — so the assembly reports on itself. Settling then becomes a curve you watch rather than a years-later discovery of cold corners. The house is still on that sawdust. The identified fix — blowing in cellulose, which fills like sawdust yet holds its loft — is possible but not yet scheduled. We still believe in the material itself. What House 001 has only identified, Unity Hub has designed in: the accepted concept wraps its cross-laminated timber walls in 370 mm of dense-pack blown cellulose. That is recycled paper installed at exactly the density the sawdust lesson demands. The designed wall U-value is around 0.09. The material also wins the embodied ledger outright: published measurements put cellulose at 0.94–3.3 MJ/kg of embodied energy against 10.8–45 for commercial insulation. That is the lowest of the mainstream options, before counting the carbon the recycled paper keeps stored in the wall. House 001's low-carbon construction is a line in its measured carbon balance. 11 tonnes of CO₂-equivalent come from construction-material choices: the single largest slice, and the one-time embodied part of a running total near 17 tonnes by 2026. The Hlibivka design specifies the fuller vision: hemp-based insulation in walls of 50–60 cm total thickness, chosen as much for health and breathability as for thermal numbers.

Maturity: applied. Living through seasons at House 001, including the sawdust-settling failure still in place, with a cellulose fix identified but not yet scheduled. Designed in at Unity Hub as 370 mm of dense-pack cellulose; specified throughout the Hlibivka design.

Further reading