Optimizing Thermal Insulation of Cir-Q: A Study on Mycelium-Composite Filling for Sustainable Building Components

Abstract

Mycelium composites are an emerging and novel biomaterial with significant potential to replace petrochemical-based insulation for more energy-efficient buildings. These materials offer comparable thermal insulation while being more sustainable, 100% circular, and less energy-intensive. This research centers on optimizing the thermal insulation properties of Cir-Q, a sustainable building component designed by FC-i in collaboration with Comfortdak. Cir-Q consists of mycelium composites used as insulation fillings, encased in oriented strand board (OSB) for structural support. The current production method involves a sawing-then-compressing strategy, where dried and shaped mycelium composites are compressed into OSB cases, aiming to eliminate gaps between the mycelium material and the OSB. However, the challenge lies in controlling the degree of compression to avoid increasing the material's thermal conductivity. This research addressed two main objectives: first, to test and compare the thermal insulation properties of two mycelium composites produced by FC-i, both derived from the same fungal species G. lucidum but cultivated on different substrates; second, to conduct compression experiments on the materials, measuring changes in density and thermal conductivity before and after different levels of compression, as well as assessing the rebound capability of the materials to predict the optimal compression rate for mycelium fillings. The results of this study indicated that the two mycelium composites (0.0539- 0.0666 W/Mk) did not show significant differences in their thermal insulation properties, though both were lower than those of commonly used insulation materials. Notably, the study found that when the materials were mildly compressed by 10% or 20%, their thermal conductivity slightly decreased rather than increased, and the materials demonstrated excellent rebound performance, stabilizing within three days with no observed shrinkage. Additionally, even when compressed 40% or 50% of their original volume, the thermal insulation properties of the materials did not change statistically, while their compressive strength significantly improved. Furthermore, it was noted that as the mycelium composites were compressed, the thermal conductivity initially decreased, reaching a minimum point, then began to increase as density continued to rise. This trend was explained by possible changes in the porosity and pore size within mycelium composites during compression. These findings offer promising prospects for the further development of Cir-Q products.