Analysis of Decarbonisation and Energy Efficiency Improvement Through Mycelium, Hygromorphic Wood and Hemp

Decarbonising the building sector requires addressing both embodied carbon in materials and operational energy for indoor conditioning. This article critically reviews the potential of mycelium, hygromorphic wood and hemp as emerging natural materials for low-carbon construction, comparing them with conventional materials only within function-specific applications such as envelopes, insulation, non-load-bearing components and passive systems. Recent comparative literature shows that mycelium composites can reach thermal conductivities of 0.026–0.12 W/m·K and densities of 51–280 kg/m3; in wood–mycelium formulations, an average density of 167.5 kg/m3 and climate impact of 2.13 kg CO2-eq/kg with a conventional electricity mix, reduced to 0.66 kg CO2-eq/kg with renewable energy, have been reported. Hemp shows typical densities of 140–540 kg/m3, conductivities of 0.061–0.12 W/m·K, compressive strengths of 0.3–3.5 MPa and potentially negative climate performance of about −40 to −80 kg CO2-eq/m3, compared with +300 to +400 kg CO2-eq/m3 for conventional concrete. Hygromorphic wood is relevant not as insulation or a primary structural replacement, but as a passive actuation material for adaptive envelopes. Hemp is currently the most mature option, mycelium is promising for circular non-structural panels and insulation, and hygromorphic wood is an operational-modification strategy whose building-level energy benefits still require direct quantification. Cross-study comparisons should be interpreted as bounded ranges because composition, fabrication, testing and LCA (Life Cycle Assessment) system boundaries vary substantially across the literature.