Water vapor sorption dynamics in different compressions of eelgrass insulation

Department of the Built Environment, Aalborg University, 9220 Aalborg, Denmark

^* Corresponding author: kmf@build.aau.dk

Abstract

Eelgrass shows potential in meeting the rising demands towards new, sustainable materials. It hosts a range of characteristics that benefits its application as a building material, such as thermal and acoustic insulating properties that can compete with conventional mineral wool insulation. However, as a porous bio-based building material, the moisture performance of eelgrass must be assessed to ensure its practical application. In this study, experimental investigations are conducted by a new automated vapor sorption analyzer (VSA) to measure adsorption and desorption of water vapor on different compressions of eelgrass insulation, ranging from loose strands to densely compacted insulation batts. Overall, higher sorption dynamics are observed in eelgrass insulation compared to conventional mineral wool insulation. Loose strands of eelgrass depict higher dynamics (including hysteresis) for the full range of relative humidity in comparison to insulation batts, potentially due to additional binder. Increasing the compression of eelgrass insulation batts results in lower sorption dynamics in the >70% relative humidity range. A Guggenheim-Anderson-deBoer model is applied that shows good fit with the experimental data and may be applied in moisture transfer calculations. This study furthers the potential of compressing eelgrass for application in passive design strategies through its moisture buffering capabilities.