Moisture Buffering in the Indoor Environment

Abstract: Moisture buffering in the indoor environment is the ability, through absorption and desorption, of surface materials to attenuate the moisture variations of the indoor air. Moisture buffering plays an important role in understanding the risks for biological growth in surface materials in the indoor environment, e.g., mold growth on walls and house dust mites in beds, and thereby also have an impact on the health of the inhabitants. Apart from the health aspects, moisture buffering is also important to take into account in hygrothermal calculations as well as for design of indoor climate systems. The interaction between surface materials and the humidity of the indoor air is the scope of this Ph.D.-project reported in this thesis. The main objective is to enhance the understanding of the moisture buffering of surface materials in the indoor environment. The focus has been on moisture buffering in textile materials and upholstered furniture, common to Scandinavia. The moisture buffering has been investigated through experimental work, field measurements and modeling. The experimental work covers development of laboratory methods and determination of basic material properties to full scale climatic chamber measurements. A definition scheme regarding the moisture buffering in the indoor environment, at three spatial levels ?material, component and room level, is proposed. Within the project, a method, to determine sorption isotherms has been developed. The moisture sorption properties for textile materials, common in the indoor environment, have been determined. The moisture conditions in a chair seat and in two bed systems have been investigated through climatic chamber measurements and field measurements, respectively. Both types of upholstery have also been studied through mathematical models. The impact of furniture and furnishing, on moisture buffering performance, was studied in a full scale climatic chamber study. The main conclusion from the project is that moisture buffering in furniture and furnishing will be important in the moderation of indoor humidity variations with short time scales (hours and days).