Construction industry is increasingly prioritizing sustainability through life cycle assessment, aiming to evaluate its environmental impact at every stage. The cradle-to-cradle approach emphasizes the use of materials designed with end-of-life reuse or biodegradability in mind. Mycelium, the root-like structure of fungi, offers a solution to these challenges. It can be cultivated on agricultural waste, obtaining panels made of organic residues, made more compact and durable. The aim is to obtain mycelium-based products that are fully biodegradable, in line with the principles of circular economy. To assess the feasibility of mycelium in construction, heat and moisture transfer (HMT) simulations can be utilized. A preliminary study is carried out on three types of commercial mycelium panels prepared with different substrates. The samples are tested using a Dynamic Vapour Sorption Analyser. The moisture sorption curve, the Moisture Buffer Value (MBV) and the water vapour resistance factor are estimated, using the dynamic vapour sorption measures. Finally, the material properties are used to quantify the effects in WUFI Plus: a small office room is considered as a case study, and the effect of the panels is evaluated on the temperature and relative humidity of the room and on the HVAC system consumption.