Hygrothermal performance of internal insulation systems with moisture-adaptive vapour retarders

In this study, the hygrothermal performances of a moisture-adaptive vapour retarder in form of a paint coating is investigated via numerical simulation with the software Delphin. The vapour retarder is combined with an exemplary internal insulation system by analysing the temperature and moisture distribution in the construction under different boundary conditions. Simulations are performed to determine the limits of the system in relation to the risk of moisture damages due to mould growth and to optimize the water vapour diffusion resistance factor of the vapour retarder (sd-value) as a function of the relative humidity. The impact of different construction parameters (thicknesses of the wall and insulation layer), employed materials and boundary conditions (driving rain, solar radiation, internal and external temperature/relative humidity) are investigated. The numerical results reported in this study serve as pre-dimensioning of the vapour retarder and support future development of applicative solutions.