Upcycling wheat and barley straws into sustainable thermal insulation: Assessment and treatment for durability

This study investigates the potential of wheat and barley straws as sustainable alternatives to conventional insulation materials. The focus is on evaluating the risk of mould growth in straw-filled wall assemblies across different climate types, while comparing the physical, thermal, hygroscopic, and durability properties of wheat and barley straws. Additionally, the effectiveness of boric acid as an antifungal treatment on straws is assessed. The findings reveal that both barley and wheat straws exhibit low thermal conductivity, ranging from 45 to 65 mW m−1 K−1 for bulk density of 60 to 100 kg m−3. Notably, barley straws demonstrate lower sorption capacity, higher vapour diffusion, lower thermal conductivity, and reduced mould growth intensity, rendering them more suitable as insulation material. The application of boric acid treatment effectively enhances the mould resistance of straw without adversely affecting their hygric and thermal properties. Consequently, boric acid treatment is recommended for wheat straw under unfavourable climatic conditions.