Abstract

The moisture buffering effect of interior hygroscopic materials can reduce the variation of indoor RH, thus to achieve a desired indoor environment and to obtain a better building envelope performance while saving energy consumed in operating HVAC equipment. Even though a large number of studies have been conducted to investigate the moisture buffering effect, additional studies are still required for several major questions including: 1) How to evaluate the impact of different parameters on moisture buffering potential under different conditions? 2) Is the local moisture buffering of surface materials influenced by non-uniform indoor conditions? 3) Can hygroscopic materials be categorized and ranked in order to achieve a better moisture buffering application? Aiming to answer these questions, this research is developed and carried out to define an index to quantitatively evaluate the impact of different parameters on moisture buffering potential of interior surface materials and furniture, to investigate moisture buffering of surface materials under non-uniform indoor conditions and to classify hygroscopic materials. These objectives are achieved through both experiments and simulations including 1) analysis of the moisture balance established in a full-scale experimental testing (28 cases) and whole building Heat, Air and Moisture (HAM) simulations (54 cases BSim simulations); 2) investigation of local moisture buffering of interior surface (WUFI) applied on test walls; and 3) analyses of moisture buffering capacity at material level using WUFI simulations. A new index, maximum accumulated moisture buffering value (MAMBV), is developed to quantify the impact of different parameters on the moisture buffering effect. The great advantage of this index is that it can provide a direct comparison of moisture buffering potential in different test scenarios. The parameters investigated include daily moisture load rate and schemes, ventilation rates, supply air conditions, volume rates, and different interior surface materials and furniture. The distribution of local moisture buffering of surface materials are analyzed for the first time and the locations where surface materials provide higher moisture buffering is identified. The moisture response, including moisture buffering capacity, moisture history effect, and time factor involved are fully investigated. Based on these analyses, hygroscopic materials are categorized into three groups, which are determined by materials' moisture capacity and vapor transfer resistance factor. This thesis presents a comprehensive evaluation of the impact of different parameters on the moisture buffering effect under realistic indoor conditions, advances the current understanding of moisture buffering capacity of materials, and brings foreword a new contribution toward moisture buffering design and application.