## 1 Introduction  
### Moisture Problem in Building Heritage  
Water is universally acknowledged as one of the most damaging agents impacting historic masonry structures, driving both immediate and progressive deterioration [1, 2, 3, 4]. Water infiltration threatens structural integrity and human health, with direct consequences including material degradation (e.g., surface erosion, freeze-thaw damage, salt crystallization, and metal corrosion) and reduced thermal performance. Indirectly, persistent moisture promotes mold proliferation, elevating indoor humidity and respiratory health risks. Moisture can be conveyed into ancient buildings materials mainly through capillary rise, condensation, rainwater infiltration, leakage from water pipes, and flooding. It therefore causes or worsens all the decay processes in building materials such as rain wash, freeze-thaw effects, migration, and crystallization of soluble salts, chemical and biological attacks, and corrosion of metallic elements [5, 6, 7, 8, 9, 10]. Salt deterioration is one of the most important contributors to the weathering of porous materials in historical buildings and the works of art they may enclose. This form of damage predominantly occurs through repeated crystallization-dissolution or hydration-dehydration cycles, which are strongly influenced by relative humidity (RH) and environmental temperature--highlighting the importance of environmental control as a vital mitigation strategy [11; 12; 13]. Beyond external environmental conditions, it is essential to analyze the internal climate of buildings to identify long-term trends in air temperature and humidity. This article defines microclimate at the scale of room air volume by examining these variables [14; 15]. [PERSON] et al. [16] observed that the indoor microclimate in historic buildings is strongly influenced by outdoor environmental conditions. A comprehensive understanding of indoor climatic conditions is essential for assessing long-term trends in air temperature and humidity within historical buildings. This study analyzes indoor microclimate dynamics at the room scale [14; 15]. Although standards such as uni 10829 (1999) [17] emphasize monitoring both the external environment and indoor microclimate as part of conservation risk assessments [18], practitioners often allocate minimal resources to pre-restoration monitoring. In many cases, monitoring periods are limited to just a few months, rarely exceeding one year [19]. These standards are primarily applied in museum settings, where artifacts such as frescoes require strict environmental control. Similarly, microclimate monitoring is more routinely implemented in historical buildings with valuable surface decorations, whereas undecorated structures receive less attention [20]. The recent research on microclimate monitoring has shifted focus toward analyzing microclimate dynamics in heritage buildings, guided by established standards and protocols [21; 22; 23]. However, applying universal standards across diverse historic sites presents challenges due to variations in materials, climate, and context. To understand a building's hygrothermal behavior, it is necessary to evaluate both the internal microclimate and its relationship with the external environment [24]. This interaction helps detect risks such as surface condensation, moisture accumulation, and material degradation. The building's response to external conditions depends on factors like heat and moisture exchange, air infiltration, thermal inertia, and the balance between surface temperature and dew point, all of which shape the indoor microclimate in historic structures. While these interactions are inherently due to the unavoidable ecosystem between indoor and outdoor environments, they can lead to critical moisture-driven decay cycles--such as freeze-thaw, salt crystallization, and mold growth--regardless of the building's envelope performance or the presence of mechanical systems [25; 26; 27; 28].