Website of the Belgian thermal regulations for buildings. Straw does not have a specific lambda value. There is generic values for non-specific biobased materials: 0.06 W/m.K for processed insulation material, 0.08 for in situ insulation. We recommend using the 0.06 for straw bales (Panneaux ou rouleaux d’isolant à base de fibres végétales ou animales, fabriqués en usine, autre que la cellulose, avec 50 ≤ ρ ≤ 150kg/m³. pe 83/118 of the attached PDF)
Link: energie.wallonie.be/
Added by: huguesdelcourt