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The research presented in this paper shows that moisture transfer between indoor air and hygroscopic building structures can generally improve indoor humidity conditions. This is important because the literature shows that indoor humidity has a significant effect on occupant comfort, perceived air quality (PAQ), occupant health, building durability, material emissions, and energy consumption. Therefore, it appears possible to improve the quality of life of occupants when appropriately applying hygroscopic wood-based materials. The paper concentrates on the numerical investigation of a bedroom in a wooden building located in four European countries (Finland, Belgium, Germany, and Italy). The results show that moisture transfer between indoor air and the hygroscopic structure significantly reduces the peak indoor humidity. Based on correlations from the literature, which quantify the effect of temperature and humidity on comfort and PAQ for sedentary adults, hygroscopic structures can improve indoor comfort and air quality. In all the investigated climates, it is possible to improve the indoor conditions such that, as many as 10 more people of 100 are satisfied with the thermal comfort conditions (warm respiratory comfort) at the end of occupation. Similarly, the percent dissatisfied with PAQ can be 25% lower in the morning when permeable and hygroscopic structures are applied.

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This study reports on the unique water vapor adsorption properties of biomass-derived starch particles (SPs). SPs offer an alternative desiccant for air-to-air energy exchangers in heating, ventilation, and air conditioning systems because of their remarkable adsorption–desorption performance. SP 15 has a particle diameter ( d p ) of 15 μm with a surface area (SA) of 2.89 m 2 /g and a pore width ( P w ) of 80 Å. Microporous starch particles (SP 15 ) were compared with high amylose starch (HAS 15 ; SA = 0.56 m 2 /g, d p = 15 μm, P w = 46 Å) and silica gel (SG 13 ; SA = 478 m 2 /g, d p = 13 μm, P w = 62 Å). Transient water vapor tests were performed using a customized small-scale energy exchanger coated with SP 15 , HAS 15 , and SG 13 . The water swelling (%) for SP 15 was ca. 2 orders of magnitude greater with markedly higher (ca. three- and six-fold) water vapor uptake compared to HAS 15 and SG 13 , respectively. At similar desiccant coating levels on the energy exchanger, the latent effectiveness of the SP 15 system was much improved (4–31%) over the HAS 15 and SG 13 systems at controlled operating conditions. SP 15 is a unique desiccant material with high affinity for water vapor and superior adsorption properties where ca. 98% regeneration was achieved under mild conditions. Therefore, SPs display unique adsorption–desorption properties, herein referred to as the “Goldilocks effect”. This contribution reports on the utility of SPs as promising desiccant coatings in air-to-air energy exchangers for ventilation systems or as advanced materials for potential water/energy harvesting applications.