Vegetal aggregates-based materials, as hemp concrete, are used to improve thermal insulation, acoustical and hygrothermal performances for a better living comfort in buildings, by using renewable resources. Hemp concrete is frequently used. However, the lack of knowledge about its long-term performances is a limitation to the development of the material. Therefore, the objective of this study of durability is to identify the ageing mechanisms of hemp concrete by using a pluridisciplinary and multiscale approach. Hemp concrete is aged for two years under two different environmental conditions, the factors of ageing used are temperature and variations of relative humidity. The evolution of functional properties (thermal, acoustical and mechanical) is followed and related to the evolution of microstructure and chemistry of the different components. The results show that under static laboratory conditions, the properties of hemp concrete are stable with time. The accelerated ageing allows changes in the functional properties with time, due to modifications of the binder chemistry and of the microstructure of vegetal aggregates, with an action of microorganisms.