Turning waste into insulation – A new sustainable thermal insulation board based on wheat bran and banana peels

As modern buildings are getting more and more energy efficient in their operation due to improvements in the insulation envelope and building technology, the embodied emissions of the used building materials become increasingly important for the overall carbon footprint of buildings. This necessitates the creation of materials, including thermal insulation materials, with low embodied emissions, such as biomass-based materials. Here, thermal insulation boards based on wheat bran, a milling by-product, were produced using water only or a banana peel slurry as a binder. The density dependence of the thermal conductivity and compressive strength was determined and the moisture uptake, microstructure and thermal stability were evaluated. The boards showed thermo-mechanical properties comparable to other materials based on low-value or waste biomass with their thermal conductivity ranging between 50 and 66 mW/(m·K) and stress at 10% strain values between 20 and 170 kPa. Surprisingly, the properties were not significantly different when comparing those prepared with and without the banana peel binder. The wheat bran insulation boards provide a proof-of-concept for a thermal insulation board with good thermal and mechanical properties and low embodied emissions based on a low-value agricultural by-product.