Architecture & Design

Architecture & Design | 13 chamber underlying the main altar at St John's Co-Cathedral. It was constructed at the same time as the church, in the 16th century, and houses the remains of the first twelve Grand Masters who headed the Order of the Knights Hospitaller of St. John of Jerusalem, Rhodes and Malta between 1522 and 1623. The vault of the Crypt was frescoed in the late 1720s by Nicolò Nasoni, a Florentine artist who was also responsible for the illusionistic decorative ceiling of the corridors in the Grand Masters' Palace in Valletta. The Grand Masters' Crypt is accessed from the Co-Cathedral via a straight staircase from the Chapel of the Anglo-Bavarian Langue. This is the only physical link between this underground chamber and the Co-Cathedral which permits access on foot. The other links consist of four oculi or vents located in the Crypt's vaulted roof. These oculi originally emerged at Main Altar level. However, during the subsequent re-design of the Main Altar, they were blocked off. The first stage of this conservation project, which pre- dates this technical design intervention, comprised the actual restoration of the frescoes, which was carried out between 2008 and 2012. This painstaking and delicate work was carried out by the Courtauld Institute of the UK, which employs experts in fresco restoration and preservation. This phase also included the assessment of the natural environmental conditions of the Grand Masters' Crypt, so as to understand the input required in order to achieve the target optimal temperature and humidity level, which do not naturally co-exist in nature. Hence, the necessity of an artificial means of control. Following the restoration of the frescoes, the ambient temperature and relative humidity within the Crypt were controlled with standalone A/C units, a humidifier and a de-humidifier, all of which were controlled manually. Consequently, this special space was temporarily closed off to the public. The Foundation of St. John's Co-Cathedral together with TBA Periti and Galea Curmi Engineering proposed the installation of a more sophisticated automated environmental control system, which responded efficiently and effectively to the fluctuating weather conditions. Following numerous considerations and assessments of various available technologies and equipment, a possible technical solution was identified. The only viable technological solution was deemed to be dependent on the re-utilisation of the strategically-located oculi in the ceiling of the Crypt, which were buried beneath the existing marble finish around the overlying Main Altar. This implied that these oculi had to be re-exposed and utilised as the inlets and outlets of the controlled and filtered air. As expected, there were major technical problems, which had to be solved, and which TBA Periti, together with the staff of St. John's Co-Cathedral meticulously studied. This exercise, included historic research, trial investigative works, and numerous meetings with the Superintendence of Cultural Heritage (SCH) in order to discuss the possible technical options. After about two years of discussions and research, a route for the ducts and the location for the technical equipment was finally defined, and there was enough information and confidence that, at least, two of the four existing oculi could be accessed (two oculi being the absolute minimum number of inlets required). The identified route linked the North prison at roof level, which accommodates the custom-made technical equipment and the Main Altar itself. The equipment controls the ambient conditions via two 0.30m x 0.30m square section ducts (supply and returns), which eventually branch into the existing " The challenge was not only technological, but, above all, it required a particular design solution, which had to be seamlessly integrated with the sensitive fabric of the Grand Masters' Crypt, and the Main Altar in St. John's Co-Cathedral "

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