The environmental and anthropogenic hazards of monuments: visualization procedure by IR thermography and numerical modelling

The indoor microclimate is very often the major hazard issue for the conservation of heritage buildings, including wall and wood paintings. In many cases the heating devices are requested inside the monuments, but it is difficult to forecast the long term effect on precious work of arts. Generally, the long term monitoring of the air temperature and relative humidity, coupled to visual inspection and photographic recording is the way adopted for safeguarding the monument. Sometime, additional methods are applied as for example IR thermography, but not on regular basis, due to lack of precise procedure and standards. Furthermore, the cost is a limiting factor to only a few case studies. The proposed approach is to make such a crucial phase for the monument life: fruitful, cost effective and reliable. It is based on two steps: at first a short run monitoring using a new Quantitative IR Thermography (QIRT) technique; then the modeling of different occupancy policies and Heating, Ventilating and Air Conditioning (HVAC) solutions. An additional step could be added for verifying of the plant efficiency and tuning it. In this context, the use of numerical codes is a useful tool. In fact a numerical simulation allows the calculation of the indoor parameters in a large number of internal points, also because of the performances of modern computers. The aim of this work is to set up an investigation method allowing the prediction of the best indoor conditions for the preservation of the frescos and the correct utilization. The case study is a typical example of these problems bound to the fresco's maintenance, a small church with a precious XIII century fresco, San Biagio, near Treviso in the North-East of Italy. The reported example presents a synergetic effect of results obtained by measurements and by a numerical study. Actually, a precise evaluation of the equilibrium conditions between microclimate and the materials must drive the design of any intervention, including on-off heating of the buiding or intermittent occupancy policy. The Computational Fluid Dynamic (CFD), supported by a totally new thermographic technique allows investigating the presence of excess moisture on the materials