In Europe, 40% of the total energy requirements relates to the energy consumption in the construction sector. The awareness resulted in the use of bio-based materials thanks to their small carbon footprint (Zhao et al. 2017). The aim of this study is twofold. The first objective is to gain a better understanding of the durability of traditional insulation materials such as mineral wool and PUR versus bio-based insulation (cellulose) in timber frame constructions and CLT constructions. The second objective is to evaluate to which extent this durability depends on various levels of climate change impact we might face based on the future greenhouse gas concentrations. This study uses the Mould Index as an indicator for possible degradation of the insulation layer. The mould Index is calculated using temperature and relative humidity derived from HAM simulations in Delphin 6.1.4. These simulations are done for different wall assemblies and different climate scenarios for Brussels. The results show that climate change has a negative effect on the durability of the outer part of the insulation material and that this effect is higher for cellulose than for mineral wool in timber frame construction.