Quantifying the Influence of Hygroscopic Materials in the Fluctuation of Relative Humidity in Museums Housed in Old Buildings

Abstract

The preservation of artifacts in museum collections is profoundly affected by fluctuations intemperature and, especially, relative humidity. Since the late 19th century, many studies have beencarried out into the best way to control hygrothermal conditions. Today, however, the focus is lessupon visitors' comfort than upon ensuring the stability of relative humidity.In old buildings located in temperate climate zones with strong thermal inertia, and which have lowventilation rate (relative to the volume and number of visitors), daily and seasonal hygroscopic inertiamay help to assure the maintenance of RH stabilization conditions. That is to say, active systems maybe dispensed with if the buildings' passive behaviour is used to best advantage.This paper presents the validation of an advanced hygrothermal model by comparing numerical andexperimental results of RH fluctuation in the reserves of a museum housed in an old building, locatedin Porto. The quantification of the influence of hygroscopic materials with different characteristics instabilizing the relative humidity when ventilation flows are reduced is also presented.