Design and Optimization of an Alginate Hydrogel-Based Multi-Layer EcoTile for Passive Indoor Passive Humidity Buffering
Tarini Patki
25/09/2026
High humidity within buildings in the tropics and subtropics such as India results in numerous discomforts and problems for occupants and for building components. High humidity causes increased saturation of sweat on the surface of the skin thereby increasing the apparent temperature, promotes growth of mold and mildew, causes peeling of paint from surfaces and deterioration of building components such as wood. Simple passive methods for controlling high indoor humidity without the use of electricity are required. This paper describes development of an indoor humidity buffering passive building component, EcoTile, comprising a three-layer wall tile that includes a porous outer surface for moisture absorption from the surrounding air, a hollow enclosed Alginate Hydrogel middle layer for storage of the absorbed moisture, and a flat smooth inner surface of waterproof material such as silicone for wall surface protection against moisture. A Hydrogel optimization study was performed to determine the best sodium Alginate solution concentration, and crosslinking solution concentration and ratio, by testing various formulations for crosslinking time, gel strength, flexibility, and water uptake. The Hydrogel study revealed that the best formulation for EcoTile was 2% sodium Alginate solution with 1% calcium chloride solution in a 5:3 ratio. The optimized Alginate Hydrogel performs well in terms of high water-uptake, good flexibility, and slow moisture-release over time as it dries. In a chamber-humidity-control experiment, an EcoTile sample significantly reduced the peak relative humidity by about 14% as compared to a similar chamber without the tile, and also showed a faster recovery to normal humidity after the addition of water. Thus, EcoTile offers a simple and cost-effective passive method for controlling high indoor humidity. While the study provides strong evidence in support of use of EcoTile as a component for humidity-buffering, further experimental studies in real building environments are warranted. The results of this study also suggest that EcoTile could be a useful additional passive component to traditional methods for controlling high indoor humidity.