Modeling moisture buffering of innovative plasters from material properties to room scale

Passive moisture buffering can stabilize indoor microclimates and reduce cooling energy use, yet reliable prediction across scales remains challenging. This study presents a simplified characterization-to-modeling workflow that links laboratory measurements to room-scale performance. Step-response tests in a dynamic vapour sorption (DVS) analyzer were interpreted with a Fickian diffusion model fitted via root-mean-square error minimization, yielding effective moisture diffusivities of D ∼1.84 × 10−8 m2s−1 for the lime plaster and D ∼1.17 × 10−9 m2s−1 for a plaster containing 20 % calcium alginate beads. Vapour-resistance factor functions derived from these fits and from sorption isotherms were validated against NORDTEST MBV dynamic measurements, with the best agreement for both mass change (Δm) and MBV at a surface resistance of 0.1 m2KW−1 (errors: 0.67 % lime; 1.59 % alginate). Year-long building simulations then quantified room-scale impacts: the alginate-enhanced plaster attenuated indoor RH fluctuations more effectively than lime, with attenuation factors spanning from 0.2 to 0.8 depending on the moment of the year and the simulated scenario. Energy analyses showed substantial reductions in latent cooling (up to ∼100 % in scenarios with wider indoor relative humidity control band) and up to 11.2 % lower total cooling energy versus lime, with similar sensible loads. The results demonstrate a practical, scalable pathway from material properties to performance, and highlight alginate-enhanced plasters as promising passive components for humidity stabilization and energy-efficient building design and retrofits.