Field Investigation of Moisture Buffering Potential of American Clay and Magnesium Oxide Board in a Mild Climate

Abstract

Passive humidity control in buildings can be achieved by incorporating materials that have a moisture-buffering capacity. Such materials absorb moisture at peak-moisture times and give off the stored-up moisture at low moisture times, thereby stabilizing the relative humidity of an interior. The advantages of this phenomenon include energy savings and the improvement of both thermal comfort and perceived air quality. It is necessary to investigate different materials for their moisture-buffering capabilities. In this work, the moisture-buffering potential of American clay and magnesium oxide (MagO) boards was investigated. This was done through a field study that monitored twin buildings under different operation scenarios. One was set as the reference building, and its interior was finished with gypsum, owing to the usage of this material as a common industry practice. The second building was set as the test building and was covered with American clay and MagO boards. The operational congruency of the buildings was checked, and then, three tests were conducted to simulate the interior finishes of a building, ventilation effects, and occupancy density. It was found that the American clay exhibited a better moisture buffering potential than gypsum, especially in the comparison of as-built surface conditions. Further, the experimental results also showed that the moisture-buffering potential of MagO boards may be comparable to that of gypsum, and a coating of vapor-open MagO boards is beneficial for humidity regulation.