This study evaluates the environmental impacts of mycelium-based composites (MBCs) through a life cycle assessment (LCA) of a laboratory-scale production process in Germany. MBCs, made from organic substrates like hemp or sawdust, are gaining attention for their potential in construction due to their acoustic, thermal, and fire safety properties. The LCA compares MBCs with conventional insulation materials and highlights their environmental advantages and challenges. Key findings include: - MBCs have a lower climate change impact (0.3668 kg CO₂e/kg) compared to extruded polystyrene, quadcore sandwich panels, foam concrete, and rock wool. - MBCs have lower fossil energy demand but higher land and water use compared to conventional materials. - The production stage dominates the environmental impacts, particularly in fossil energy demand, climate change, acidification, eutrophication, and ozone formation. - The use of sawdust as a substrate reduces environmental impacts, especially in water scarcity and land use. - MBCs perform better than many conventional insulation materials in terms of climate change impact, but they have higher water and land use demands due to hemp cultivation. - Sensitivity analysis confirms the robustness of the LCA results, with consistent mean values and symmetric distributions for most impact categories. The study suggests that MBCs can be a sustainable alternative to conventional materials, especially when using renewable energy and specific substrates like sawdust. However, further research is needed to address scalability, raw material availability, and regulatory compliance.This study evaluates the environmental impacts of mycelium-based composites (MBCs) through a life cycle assessment (LCA) of a laboratory-scale production process in Germany. MBCs, made from organic substrates like hemp or sawdust, are gaining attention for their potential in construction due to their acoustic, thermal, and fire safety properties. The LCA compares MBCs with conventional insulation materials and highlights their environmental advantages and challenges. Key findings include: - MBCs have a lower climate change impact (0.3668 kg CO₂e/kg) compared to extruded polystyrene, quadcore sandwich panels, foam concrete, and rock wool. - MBCs have lower fossil energy demand but higher land and water use compared to conventional materials. - The production stage dominates the environmental impacts, particularly in fossil energy demand, climate change, acidification, eutrophication, and ozone formation. - The use of sawdust as a substrate reduces environmental impacts, especially in water scarcity and land use. - MBCs perform better than many conventional insulation materials in terms of climate change impact, but they have higher water and land use demands due to hemp cultivation. - Sensitivity analysis confirms the robustness of the LCA results, with consistent mean values and symmetric distributions for most impact categories. The study suggests that MBCs can be a sustainable alternative to conventional materials, especially when using renewable energy and specific substrates like sawdust. However, further research is needed to address scalability, raw material availability, and regulatory compliance.