ReSeMM Project – Development of a multimodal sensor network for structural and environmental monitoring. Spoke 6, Intervention site: Benedictine Monastery, Catania
The project was carried out as part of the PNRR Spoke 6 public tender, Mission 4 “Education and Research” – component 2 “from research to business” – investment line 1.3 “Partnerships extended to universities, research centers, and companies for the financing of basic research projects” – research and innovation program “Changes – Creativity and Intangible Cultural Heritage,” funded by the European Union – NextGenerationEU.
The initiative involved, for the sites indicated in the call for proposals and in compliance with the instructions of the client and the local authorities responsible for protection, the design and supply of a multimodal sensor network and the creation of a cloud-based software platform, integrated with a geospatial database, capable of remotely managing the network, acquiring, storing, processing, and displaying the collected data in real time, and setting alarm thresholds.
The project, coordinated by the Department of Civil Engineering (DICIV) of the University of Salerno, with Prof. Luigi Petti as Scientific Director, also involved the Departments of Industrial Engineering (DIIN) and Cultural Heritage Sciences (DISPAC), together with the innovative start-up Modula S.r.l..
Objectives
Architectural and archaeological heritage is exposed to dangers and risks, not only natural and anthropogenic, but also climate change; added to this are the natural processes of degradation generated by the aging of materials and the variability of environmental conditions. With a view to the sustainable use of resources and heritage protection, the development of methodological approaches that promote minimal intervention and proactive maintenance plays a key role in the management process. The proposal aims to implement a model and an integrated multi-scale and multi-level monitoring network through the development of robust and expandable systems that guarantee constant monitoring of the state of health of the assets, allowing the behavior of the structures to be characterized, including through the implementation of BIM models to document the life cycle of the structures and the development of predictive models.
The monitoring project developed for the Benedictine Monastery of San Nicolò l’Arena stems from the need to continuously and scientifically accurately monitor the structural, microclimatic, and conservation conditions of one of the largest and most layered monumental complexes in Europe. The intervention focuses on three main areas—the East Cloister, the refectory rooms, and the Domus Romana—each with its own critical issues and functional characteristics that require different monitoring approaches, selected and calibrated according to the morphology of the spaces, the construction materials, and the conservation risks.
Ground floor plan of the Benedictine Monastery in Catania, highlighting the refectory and the eastern cloister, areas subject to monitoring
Plan of the basement of the Benedictine Monastery in Catania, indicating the area of the Domus Romana, which is subject to monitoring
The Chiostro di Levante (East Cloister) is a particularly interesting part of the monastery from a structural point of view: it is an open space with a portico framing a central garden dominated by a 19th-century coffee tree. The presence of the cistern, the staggered levels, and the load-bearing walls, combined with the continuous interaction between the interior and exterior, necessitates an in-depth study of the dynamic response of the structures. In this context, high-sensitivity MEMS accelerometers are installed, instruments designed to detect very low amplitude vibrations and micro-movements which, in a historic building, can be early indicators of structural stress or variations due to external phenomena. The sensors are placed at points that represent actual behaviour nodes: one on the raised floor, using existing holes to avoid new drilling; one on the edge of the cistern, to intercept vibrations coming from the foundation slab; two in the ground, housed in specially constructed wells with no bottom and equipped with a permeable concrete casting that ensures direct contact with the soil and the correct transmission of vibrations; a fifth on the perimeter wall, essential for understanding how stresses reach vertical structures. This arrangement creates a three-dimensional accelerometer network that allows the cloister’s response to external phenomena, natural variations, or any human activity to be interpreted.
East Cloister at the Benedictine Monastery of San Nicolò l’Arena in Catania
Alongside the structural component, a temperature and humidity sensor has been installed in the cloister, which plays a fundamental role in comparing it with indoor environments. Continuous measurement of external microclimatic conditions allows for the study of heat exchange, daily and seasonal variations, and the effects that these changes can have on the most sensitive indoor surfaces.
The refectory rooms, on the other hand, are a completely different environment, where the main critical issue is related to the microclimate. These are basement rooms with no natural air exchange and a high tendency to accumulate humidity. The stone walls, iron arches, and low light levels create a situation where conservation requires rigorous and continuous monitoring. Here, the sensors installed are designed to monitor both climatic conditions and the state of the materials. Microclimatic conditions are detected by an internal sensor that continuously measures temperature and relative humidity, sending the data to the central platform. To obtain a realistic reading of temperature changes, a second sensor is positioned towards the West Cloister, located on an internal window sill facing the outside. This allows us to interpret how the external environment influences the internal environment and, above all, when conditions favorable to condensation occur.
Alongside the climate sensors, two multispectral cameras are installed in the refectory rooms, performing a highly complementary role. Unlike traditional cameras, multispectral cameras record portions of the light spectrum that are invisible to the human eye. This feature allows micro-cracks, infiltrations, pigment variations, areas of moisture accumulation, or alterations in stone surfaces to be detected before they become visible. The cameras are located in the deepest and most critical areas of the refectory, where the rock walls and lack of air exchange make hidden deterioration more likely. Their operation is automated thanks to an industrial PC installed inside the rooms, which acts as both a control unit and a dedicated Wi-Fi router. The latter aspect is essential: the cameras communicate wirelessly, avoiding invasive installations in fragile environments that are difficult to reach with cabling.
The Domus Romana, the third area under study, requires an even lighter approach. Here, the fragility of the mosaics, original flooring, and archaeological artifacts makes any invasive intervention impossible. For this reason, a single multispectral camera is used, operated manually by an operator. The images are captured directly on site and transferred via Wi-Fi or removable memory, without installing fixed sensors or altering the ancient structures in any way. This approach allows the evolution of the surfaces to be monitored and any alterations to be documented, while ensuring maximum respect for the archaeological context.
Roman House at the Benedictine Monastery of San Nicolò l’Arena in Catania
Sensor network
The entire sensor network is governed by a dual-level architecture: one part is fully wired and stable, dedicated to the East Cloister, and the other part is a mixed wired-wireless system used in the refectory rooms. In the Cloister, the accelerometers are connected in sequence via Ethernet cable with EtherCAT protocol, powered by a power injector that supplies voltage and communication on the same cable. All sensors converge in the industrial PC located in the corridor between the cloisters, a central node that sends data to the university’s IoT platform. In the refectory rooms, on the other hand, the dedicated PC communicates wirelessly with the cameras and the internal microclimate sensor, while being connected via Ethernet to the monastery network for the final transmission of data to the central collection platform. This dual system—wired where necessary to ensure reliability, wireless where needed to minimize impact—allows for constant, integrated monitoring of extremely diverse areas, producing a complete picture of the monastery’s conditions.
The result is a scientific surveillance network that combines high-precision sensors, advanced imaging technologies, and a digital architecture designed to operate continuously and discreetly, without interfering with the historical value of the site. The system is capable of collecting structural, environmental, and conservation data, which is useful not only for identifying current critical issues, but also for anticipating possible future phenomena and guiding decisions on the protection of one of Sicily’s most precious monuments.
Summary table of sensors selected for monitoring the Benedictine Monastery
The installation of sensors in the Benedictine Monastery is designed to adapt to the architectural complexity of the site and to minimize the impact on historical structures, delicate surfaces, and archaeological areas. The methods vary significantly depending on the environments being monitored.
In the East Cloister, the main objective is to detect vibrations and the dynamic response of the structures. For this reason, five MEMS accelerometers are installed at strategic points: one on the raised floor of the cloister, using existing perforations and minimizing new interventions; one at the cistern, to intercept vibrations coming from the lower level; two in the ground, inserted into specially created wells with no bottom and equipped with a permeable concrete base that ensures direct contact with the soil; and finally, one on the perimeter walls, useful for measuring how stresses propagate vertically. The network of accelerometers is connected via Ethernet cable with EtherCAT protocol, respecting the maximum distance of 50 meters between one sensor and another. The cabling follows a route designed to take advantage of already accessible spaces and reaches an industrial PC located in the corridor between the two cloisters, the central node for data collection.
Site plan showing the location of the sensors and the configuration of the connection chain
In the refectory rooms, the priority is to monitor microclimatic conditions and interior surfaces, which are highly susceptible to humidity. Two multispectral cameras are installed in the deepest and most critical areas of these rooms, where rock walls and poor ventilation increase the risk of deterioration. The cameras are not individually wired: they communicate wirelessly with an industrial PC located inside the rooms, which also acts as a local Wi-Fi router. To ensure stability and speed in data transmission, the PC is connected via Ethernet cable to the LAN network located outside the refectory. A temperature and humidity sensor is also installed inside the rooms, while a second external sensor is placed on a windowsill overlooking the West Cloister to assess climate change. This second sensor also communicates wirelessly with the industrial PC.
Site plan showing the location of the sensors and the route of the wiring to be installed
For the Domus Romana, the installation methods are deliberately minimal so as not to compromise the integrity of the archaeological site. No wiring or permanent fixings are used here. The only tool used is a manually operated multispectral camera: the operator positions it near the historic mosaic and transfers the data via Wi-Fi or SD card. The absence of fixed installations meets the need to protect particularly sensitive ancient materials.
Site basement floor plan showing sensor locations
In summary, the installation methods favor discreet, non-invasive solutions that are compatible with the historical characteristics of the environments: structured cabling and protected manholes where data continuity must be guaranteed, wireless connections in the most sensitive areas, and manual use in the archaeological part. The result is an integrated technological network designed to coexist with a complex monumental heritage without altering it.
Diagram of the monitoring system for the East Cloister of the Benedictine Monastery of San Nicolò l’Arena in Catania, showing the devices, power supplies required, and communication protocols
Diagram of the monitoring system for the Refectory Rooms of the Benedictine Monastery of San Nicolò l’Arena in Catania, showing the devices, power supplies required, and communication protocols