Canterbury Cathedral Environmental and Structural Monitoring
Customer Challenge
Canterbury Cathedral is the Mother Church of the worldwide Anglican Communion and has been a UNESCO World Heritage Site since 1988. The cathedral is a complex and prestigious site that has been in continuous use since the 7th century.
A wide range of specialised heritage and conservation professionals now assist in managing the site. Understanding the microclimates within and around the building, as well as monitoring changes within the structure itself, is essential for maintaining the fabric of the building and ensuring the safety and comfort of visitors and worshippers in this very active cathedral.
The cathedral site contains many different areas requiring monitoring, including historic artefacts, archives, wall paintings, stained glass, and structural elements of the building. Each area presents its own conservation challenges and requires detailed environmental data to support informed conservation decisions.
Why
Because of the historical importance and complexity of the site, careful monitoring of environmental conditions is necessary to understand how temperature, humidity, light exposure, and structural movement affect the cathedral and its collections.
The cathedral holds important historic artefacts such as The Black Prince’s Tester, an image of the Holy Trinity painted onto a wooden structure. Located on the south side of the cathedral and close to windows, the work is exposed to high light levels at certain times of the year. The Victorian heating system also creates a temperature gradient across the artwork, which can contribute to deterioration.
The cathedral also contains historic archives, library materials, wall paintings, medieval stained glass, and structural elements that require ongoing monitoring. Environmental data allows conservation specialists to better understand deterioration mechanisms and assess the effectiveness of preventive and interventive conservation measures.
The Eltek Solution
The Eltek monitoring system at Canterbury Cathedral was initially installed in 2007 and has evolved over the last ten years. The system demonstrates the flexibility, ruggedness, and reliability of the Eltek product range.
The versatile and modular range of sensors in the Eltek system allows a wide variety of sensors to be added whenever required. As conservation teams analyse the data in greater depth, the monitoring system can be expanded in phases to provide additional information.
Eltek Ltd works in close cooperation with Tobit Curteis Associates, who specify the appropriate monitoring equipment. Tobit Curteis Associates is a specialist practice focusing on the investigation, monitoring, and control of environmental deterioration in historic buildings and collections, as well as the conservation of wall paintings and polychrome surfaces.
For The Black Prince’s Tester, an Eltek data logging system was installed to understand the environmental conditions affecting the artwork and to evaluate the effectiveness of preventive measures. Sensors deployed included:
• Visible and ultraviolet light sensors
• Crack meter
• Surface temperature, ambient temperature, and radiant temperature
• Humidity sensors
• Local weather monitoring
Across the cathedral site, temperature, relative humidity, and surface temperature are recorded at multiple locations including the main body of the cathedral, the crypt, and the roof spaces. A weather station records external conditions including temperature, wind speed and direction, and rainfall.
Using Eltek repeaters to extend the radio range of transmitters allowed the monitoring system to be expanded beyond the main cathedral building. This enabled monitoring of outlying buildings and heavily constructed archive strong rooms.
The monitoring system was later expanded to support stained glass conservation. Conservators required data on the conditions surrounding important medieval glass panels and needed to measure the effectiveness of conservation treatments. Additional sensors were developed to measure surface wetness and airflow, alongside surface temperature, ambient temperature, and relative humidity.
The monitoring system was also extended to support structural monitoring across the cathedral. This included crack sensing to monitor movement in joints and structural elements. Inclinometers measure the effects of wind loading and bell ringing in the Bell Harry Tower, while piezo sensors installed in boreholes monitor the movement of the water table around the building.
Measurable Results
The monitoring system has been running continuously since 2007 and has expanded to include approximately seventy transmitters and two hundred data channels.
The Darca Heritage software enables this complex collection of environmental and structural data to be downloaded, analysed, and interpreted within a single software platform. The software calculates parameters such as absolute humidity and dewpoint temperature using the recorded physical measurements.
The site is divided into zones relevant to each user group so that the most relevant information is immediately available to those responsible for conservation, maintenance, and site management.
The monitoring data provides insight into the thermal and moisture buffering behaviour of the building envelope, the risk of salt activity within historic materials, and the effect of visitor flow on the internal environment.
Strategic Impact
The monitoring system at Canterbury Cathedral demonstrates how long term environmental and structural monitoring can support the conservation of complex historic buildings and their collections.
By combining a flexible sensor network with detailed environmental analysis, the system allows conservation specialists to understand deterioration processes and assess the effectiveness of conservation strategies over time.
The ability to expand the system as new monitoring requirements arise ensures that Canterbury Cathedral can continue to manage and protect its historic fabric and collections effectively.
