Church buildings such as Xanten Cathedral are unique buildings. Their thick walls and large interior volume create a specific indoor climate that must be neither too dry nor too damp, neither too warm nor too cold. If, for example, warm, humid air enters the cold walls in summer, the moisture condenses. The resulting condensation can lead to mould growth on walls or objects such as the precious art treasures in the cathedral. Controlling the indoor climate of Xanten Cathedral has long been an art in itself.
From 2026, the system will be controlled automatically. Artificial intelligence will determine the ventilation and heating settings. It will decide, for example, whether the windows need to be opened or the heating temperature adjusted. In order to achieve the optimal church climate, the AI has been trained since last year using climate and weather data as part of a project. This was made possible by the INDUSTR_I4 small projects fund. Thanks to funding from the Interreg VI programme, the Dutch company Abracadata was commissioned by the Xanten Cathedral Workshop to train the AI.
This is how heating control is being brought up to date
Sensors provide the data for the AI. The first small grey boxes were installed in Xanten Cathedral back in 2019. Around 20 sensors now monitor the local climate: room temperature, CO₂ levels and humidity, as well as the surface temperature of walls and works of art, including, for example, 16th-century tapestries and 15th-century carved altars. The sensors are well hidden in places such as the cloister, by the altar, near the organ, and also on or under the pews. They transmit their data to a LoRaWAN gateway. This wireless transmission system was installed by the IoT Lab several years ago. A ventilation indicator shows whether doors and windows should be kept closed or opened. To do this, it compares the humidity levels inside and outside.
The IoT Lab, headed by Prof. Dr.-Ing. Rolf Becker, provided technical support for the automation of the old heating control system. Previously, the heating switches in the basement of Xanten Cathedral had to be switched on and off manually. The heating system, which dates back to the 1970s, works perfectly. Only a few adjustments were needed to integrate the AI. The IoT Lab provides the interface for the control system and supports the connection. To this end, control modules were produced using 3D printing and attached to the system’s housing with magnets. They now operate the switches on command from the AI. This brings to life a vision that, six years ago, still sounded like a distant dream to Johannes Schubert, head of the Xanten Cathedral Workshop.