As part of the global transformation to a circular economy, modern society faces the challenge of developing sustainable building materials that do not deplete nonrenewable resources or generate environmentally destructive waste. Bio-composites based on fungal mycelium grown on agricultural waste streams have the potential to serve this purpose, reducing the ecological impact of the construction industry and the conventional materials on which it currently relies. In addition to the possible advantages in the production and postuse phases of their life cycle, mycelium bio-composites are lightweight and highly insulating, thus providing valuable thermal properties for reducing energy consumption and emissions over the operational lifespan of the building. In this study, a comprehensive life cycle assessment of mycelium bio-composites was conducted, focusing on the embodied energy (EE) and embodied carbon (EC). Part of the CO2 that is emitted is the result of the fungal growth. Therefore, a novel calculation method was developed to assess the metabolic carbon emissions as a function of weight loss during the growth period. Using a cradle-to-gate model of the production process, the EE of the mycelium bio-composite was estimated to be 860 MJ m–3, which represents a 1.5- to 6-fold reduction compared with that of the common construction materials. The EC was calculated to be −39.5 kg CO2eq m–3, its negative value indicating that the fungal bio-composite effectively functions as a CO2 sink, in contrast to currently used construction materials that have a positive EC. The incubation stage of mycelium bio-composite production made up the largest portion (73%) of the overall energy, while metabolic CO2 comprised a significant proportion (21%) of the overall emissions as well. Altogether, our results demonstrate that using bio-composite building materials based on fungal mycelium and local plant residues can provide a sustainable alternative to current practice.

Material development based on fungal mycelium is a fast-rising field of study as researchers, industry, and society actively search for new sustainable materials to address contemporary material challenges. The compelling potential of fungal mycelium materials is currently being explored in relation to various applications, including construction, packaging, “meatless” meat, and leather-like textiles. Here, we highlight the discussions and outcomes from a recent 1-day conference on the topic of fungal mycelium materials (“Fungal Mycelium Materials Mini Meeting”), where a group of researchers from diverse academic disciplines met to discuss the current state of the art, their visions for the future of the material, and thoughts on the challenges surrounding widescale implementation.