Can books and textiles help in controlling the indoor relative humidity?

The control of the indoor relative humidity is important with respect of its influence on comfort, indoor air quality, mould growth, durability and energy consumption. One of the measures to passively control or regulate the indoor relative humidity is using the moisture buffering capacity of finishing materials. Building materials such as hygroscopic stuccos and untreated wood can be used for this purpose. In practice these materials often are treated with a paint limiting their buffer capacity. As a consequence, not only the finishing building materials, but also furnishing materials, books and magazines, cloths of curtains, pillows, blankets, etc. may contribute to the moisture buffering capacity of rooms. Recent research shows that those materials may have an important impact on the moisture buffering performance of a room and also may create stable microclimates. In this paper we focus on the role of books and textiles in order to regulate the indoor relative humidity. Measurements show that moisture buffering of books normal to the fore-edge is higher than for the paper alone, because moisture can penetrate deeply into books due to the presence of the thin air layers between the paper sheets. The vapour transport mechanism through the air layer towards the paper is found to increase substantially the possible active area for moisture buffering. In the same way, textiles have to be considered as a bunch of moisture buffering fibres in a loose air environment showing a huge active area but with limited buffering due to the small thickness. In this paper, we present an approach to describe the dynamic sorption behaviour of book and textiles using effective moisture transport properties. Experimental work includes scanning electronic microscopy (SEM) analysis of paper and textile, water vapour permeability measurements and sorption curves. Dynamic tests are also used to determine the moisture transport properties of book and textile. Using a modelling approach, the effective moisture capacity, permeability and effusivity of book and textile is determined. Finally, the effect of the presence of books and textiles in a reference room on the indoor relative humidity is examined though simulation.status: publishe