Environmental potential of fungal insulation: a prospective life cycle assessment of mycelium-based composites

Abstract Purpose Bio-based insulation materials are one of the most promising solutions for reducing the environmental impacts of building envelopes. Among these materials, the environmental benefits of mycelium-based materials have merely been investigated, despite their promising technical and thermal properties. In this paper, we perform a first prospective cradle-to-grave life cycle assessment (LCA) of mycelium-based composite blocks. Methods An attributional cradle-to-gate LCA of the laboratory production of mycelium-based composites was first performed, including 11 environmental impact indicators. Then, scenarios were defined to scale up the technology to the level of industrial production, including the remaining life cycle modules to perform a cradle-to-grave analysis. Biogenic and metabolic carbon were considered by applying the static −1/+1 approach and following the current LCA standards. Future-oriented energy and transport mixes were also included as an additional scenario, systematically modifying both the foreground and background data. Finally, the industrially scaled-up technology and alternative insulation materials were compared with these future conditions (as applied to both materials). Results and discussion Considering climate change, the results are encouraging in comparison to those for traditional plastic insulation, but do not necessarily surpass those for other existing materials such as rock wool. However, trade-offs are observed in other indicators, for which mycelium-based composites tend to perform worse than traditional insulation materials. The industrial scale-up reduced impacts for most indicators, but a considerable trade-off was observed with regard to terrestrial ecotoxicity. The main driver for the remaining greenhouse gas (GHG) emissions was found to be the electricity use during the manufacturing phase. We consider the inclusion of the other life cycle stages as relevant, as this increased the GHG emissions by 10%. Limitations of the current LCA standards, however, are noted and discussed, especially regarding the cascading use of biogenic materials, and highlight the relevance of this case study. Conclusions Mycelium-based composites show a potential for future development, but careful attention should be paid to reducing electricity needs in their manufacturing process. Further improvements could also be made by using fast-growing biogenic materials as a substrate. In particular, we encourage researchers to include all of the life cycle stages in future studies, especially if biogenic emissions are considered.