Fluctuations in the indoor environment in Spanish rural churches and their effects on heritage conservation: Hygro-thermal and CO 2 conditions monitoring

Abstract

The indoor environment and its natural dynamics in small Spanish historical churches such as the studied here depend on the variations of outdoor climate and the moisture dynamics of walls, built with different materials. Such indoor environments are impacted by local factors, which may put at risk the conservation of a church's cultural assets. Natural ventilation in spring, the presence of people and especially the wintertime use of ageing heating system induce substantial fluctuations in indoor environments primarily affecting the stability of relative humidity (RH). RH is the physical parameter that can induce efflorescence as well as plaster blistering and detachment in its inside walls, drying and cracking in the timber and efflorescence and disgregation in the carved dolostone.Where the RH inside building is not high, as in the present case, natural and induced fluctuations may lower it considerably (<25 %), which is detrimental to conservation and human well-being both. Human presence partially counters the steep declines in RH attributable to heating in winter and warm, dry summer weather, although the trade-off is a rise in CO 2 levels inside the church.Heating induces substantial changes in the T and RH on the high altar and in the upper areas of the nave, while natural ventilation affects the RH at the base of the church and favours the elimination of CO 2 . The results obtained have allowed us to develop a series of recommendations that might be useful for the preventive conservation of such historic buildings, without compromising human comfort.

The influence of environmental parameters in the biocolonization of the Mithraeum in the roman masonry of casa di Diana (Ostia Antica, Italy)

“…During the month of August, the tours were not held, as the BCasa di Diana^and all the other domus were closed to the public. Two guided tours had a great influence on the average value, one in June and one in October, due to the high number of visitors, as it usually happens (Varas-Muriel et al 2014). Unfortunately, the exact number of tourists that visit the site is unknown: during the guided tours, in addition to the official list, other people join without having booked the visit, and therefore their presence is not recorded.…”

“…Therefore, the evaluation of the concentration of carbon dioxide (CO 2 ) is an important indicator not only of the indoor environmental conditions in buildings (Varas-Muriel et al 2014) but also of the conservation state of historical buildings. In the sense, the works found in literature distinguish two different themes: the biological proliferation and the relative damage on the stone materials (Ascaso et al 2002, Ascaso et al 1998, de los Ríos et al 2009, Guiamet et al 2012, Mohammadi and Krumbein 2008, Schabereiter-Gurtner et al 2002.…”

“…Specifically, the CO 2 parameter control is focused on several issues: the excretion of organic acid from the photosynthetic apparatus (Adamo andViolante 2000, Lee andParsons 1999), the increase in chemical dissolution and frost wedging of rock surfaces caused by the water holding capacity of some species (Bjelland and Thorseth 2002), the damage caused by chromatic alteration (Barone et al 2008). However, the control of indoor CO 2 concentration is also related to human studies were never conducted to evaluate the CO 2 contribution deriving from biological colonization, ranging from bacteria to more complex organisms, such as plants (Dragovich and Grose 1990, Ferdyn-Grygierek 2014, Varas-Muriel et al 2014.…”

Modeling of the aerosol infiltration characteristics in a cultural heritage building: The Baroque Library Hall in Prague

“…The increase resulted from carbon dioxide exhaled by visitors [24] and the decrease from air exchange between indoors and outdoors.…”

“…Numerous studies have already focused on indoor air characterization of libraries and museums with regard to chemical pollutants, indoors sources, chemical reactions and environmental factors [4,[6][7][8][18][19][20][21][22][23]2,24]. Moreover, the characteristics of indoor PM in museums were also studied with regard to the outdoor environment [7,9,25,26].…”