Experimental monitoring programme of the thermohygrometric parameters of the Milan cathedral
The monitoring programme has been created with the assistance of innovative and non-invasive measuring apparatus which have made it possible to characterise and complete a preliminary mapping of the temperature and relative humidity profiles within the cathedral and to identify possible critical zones and/or points. Such issues may include anomalous air temperature, surface temperature and relative humidity values such that would constitute a risk of deterioration to the works of art, the sacred furnishings or the fittings within the building. Specifically, measurements were taken at different heights from the ground using helium-filled balloon probes with a diameter of approximately 200cm.
Each balloon, which was made of a highly resistant synthetic material, had a net payload capacity of between 200g and 300g and was connected by a nylon tether to a winch in order to wind and unwind the cord and control the height. By attaching the winch to a trolley, it was possible to move the equipment with ease within the cathedral during the measuring operations and thereby to map the main parameters of interest.