Thermodynamic exchanges between the external boundary layer and the indoormicroclimate at the Basilica of Santa Maria Maggiore, Rome, Italy: The problem of conservation of ancient works of art

The Basilica of Santa Maria Maggiore, Rome, is an example of how ancient bu ildings with thick walls lessen the impact of the external temperature and humidity variations. The external influence on the internal microclimate is studied in order to gather information on how the building exchanges heat and moisture. Correlations between outdoor and indoor values are found. The results are applied to the calculation of the condensation-evaporation cyc les inside micropores due to the Kelvin effect, to assess their impact on w orks of arts placed inside and outside the Basilica. It was found that the building attenuation is not sufficient to avoid damage due to condensation- evaporation cycles on stones and plasters. Some suggestions are made in ord er to mitigate the temperature variations during the liturgical offices.