Sustainable fruition as a preventive conservation strategy for hypogeum artefacts

As well as valuable Building Heritage, hypogeum scenarios often host artefacts such as i.e. graffiti, paintings or low reliefs, but differently to them, they are characterized by very particular microclimatic conditions due to their isolation from the outdoor environment. This way, they are very susceptible to human impact due to visitors’ fruition that can cause or accelerate degradation processes. Strategies for preventive conservation of Cultural Heritage should balance Heritage conservation (i.e. building materials and surfaces, hosted goods and chattels) and public access (i.e. visitors’ fruition). In these scenarios, preventive conservation strategies are based on the definition of both interventions on technical installations (to restore or improve indoor environment conditions) and operative models for sustainable fruition (to diminish the impact of stressors on the Heritage). Combining such strategies is not viable in hypogeum environments, which can be hardly equipped by technical systems. To face with such issues, this work proposes a novel strategy for Heritage conservation inside hypogeum environments based on the joint combination between environment microclimatic characterization and visitors’ impact definition. The proposed strategy has been developed and tested on a significant case of study: Palazzo Campana's hypogeum (Osimo, Italy). This hypogeum is a typical example of man-made underground structure characterized by sandstone walls carved in artistic value high-reliefs. Currently, its walls have been becoming very friable and subsequently their surfaces have been exposing to harsh deterioration phenomena. The strategy firstly includes indoor temperature and relative humidity long-term monitoring by means of a real-time widespread sensors system, so as to evaluate microclimatic conditions and its admissible gradients. A novel visitors’ admissible impact is defined on these data, by considering visiting time and numbers of visitors so as to not alter the indoor climate conditions. Visitors’ access tests are then carried out to confirm the proposed visitors’ admissible impact. Results demonstrate the capability of the proposed combined strategies and the possible extension to other Heritage scenarios to reduce the impact of direct interventions and improve preservation aspects.