Effect of fungal species on thermal conductivity and chemical composition in mycelium-based insulation

The construction industry is a major contributor to carbon emissions and landfill waste, leading to the need for sustainable insulation alternatives. Mycelium-based composites (MBCs) have emerged as promising alternatives; they are bio based materials derived from the growth of fungal mycelium on lignocellulosic substrates. They offer low embodied carbon, waste utilisation, and low thermal conductivity (λ). However, the influence of fungal species on MBC properties (e.g. λ) remains underexplored. This study investigates the extent to which fungal species selection affects MBC thermal performance and chemical composition. MBCs were successfully produced using 18 different fungal strains (17 species) on a hemp-shiv substrate with aesthetic and textural differences observed between specimens. λ was measured using a Heat Flow Meter (ISO 8301, EN 12667, and ASTM C518). Across the different species, all MBCs measured in this study exhibited good insulation properties, with thermal conductivity values ranging from [Formula: see text] W/m·K (Pholiota adiposa) to [Formula: see text] W/m·K (Lentinus tigrinus), with statistically significant differences. Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and multivariate analysis (PCA and LDA) were used to assess chemical differences. While the multivariate analysis revealed species-specific differences in the FTIR spectra of the specimens, no significant correlation was found between spectral features and λ, suggesting that physical structure and density play a more dominant role in heat transfer properties. This study represents a large interspecies comparison of the thermal properties of MBCs, demonstrating that a range of fungal species can produce effective insulation materials. It also highlights the effectiveness of multivariate analysis in comparing FTIR spectra of bio-based materials, offering a framework for characterising chemical modifications in sustainable insulation materials. By improving understanding of species selection and its impact on thermal performance, this research contributes to advancing MBCs as effective insulation for sustainable construction.