Naturally grown mycelium-composite as sustainable building insulation materials

A novel naturally grown mycelium-composite insulation brick was bio-produced by cultivating a biocompatible and fast-growing fungus, Pleurotus ostreatus, in the rye berries feedstocks. The resultant mycelium composites consisted of a core of colonized substrate, encased by a layer of water-repellent fungal skin. The microstructure of mycelium composites shows that fungal fibers grow from feedstocks and bonded adjacent feedstocks. The impact of density and moisture on the mechanical properties of mycelium composites were studied, finding that composites with increased density presented an improvement of flexural strength under both low and middle levels of Relative Humidity (RH). However, under high level of RH, composites have a lower flexural strength but a greater deformation. The mechanical strength of mycelium composites, however, meets the existing transportation and construction requirements. Based on the measured thermal properties of mycelium composites, EnergyPlus analyses were conducted to evaluate their performance in buildings' operational energy in comparison with conventional natural insulation materials, i.e., lightweight expanded clay aggregate (LECA) and expanded vermiculite (EV). Compared with LECA and EV, the use of mycelium-composite for building insulation reduced the indoor temperature fluctuations. Compared with LECA and EV, mycelium-composite insulation reduced the total annual heating and cooling energies as well as the total annual CO2 emissions for buildings located in US Climate Zone 2-8, with the only exception being in Zone 1 or the very hot climate zone. Therefore, naturally grown mycelium-composite, as demonstrated in this study, is promising to provide sustainable building insulation materials.