A picture gallery, a great artist and his school. A few words to identify the town of Cento, birthplace to Giovanni Francesco Barbieri, nicknamed Guercino (squinter), that now hosts the greatest collection of his works in the world.
Guercino lived between the 16th and 17th centuries. As a master draughtsman, he is one of the greatest representatives of Italian Baroque painting.
The town of Cento still shows noticeable signs of a bygone time of great cultural ideas, architectural ferment and innovative city planning. These last years, they decided to enhance this important heritage by promoting the town museum 'Pinacoteca Civica' where a considerable amount of works by Guercino, his school and other important painters natives of this Italian region, are displayed.
The town museum was founded in 1839 mainly to collect the works of art recovered from Napoleon's takings, and hosted since then in Palazzo del Monte di Pietà dating back to 1782. Recently restored and enlarged, it now includes an exhibition path that stretches over two floors following a time sequence from the 15th to the 19th century. The efforts for enriching the art collection have progressed together with those for improving and rearranging the display areas, which included replacing the entire lighting system.
THE PROJECT - THE LIGHT
Upgrading the lighting system and all changes thereto formed a relevant part of the restoration works.
A twofold requirement should be met. On one hand, illumination had to better suit the characteristics of the premises and objects to be illuminated. On the other, a modern system providing reduced consumption and increased safety was required.
The previous point-light type lighting was supplied by luminaires fitted with metal iodide lamps that exhibited the following troubles: slow switch-on, humming ferromagnetic ballasts, no light-flux modulation, uneven light supplied by the lamps with remarkable colour shade differences between the lamps.
The Municipal Culture Bureau request was then for a lighting system based on indirect light, evenly illuminating the entire rooms, with low energy consumption, light-flux control, and timed switch-on capability.
It was important to reduce exposure time of the artworks to light and, at the same time, improve light quality to guarantee that the paintings be best appreciated. Installation technicalities included room dimming optimisation and the provision of a bus system that would enable control of other systems and services at a later time.
This project would allow supervising the entire lighting system from one control station and decide upon switching on/off single rooms, floors or general illumination independently. Also, the bus-type solution not only would guarantee efficient system management, but also limit cable routing in the rooms and reduce necessary brickwork.
THE LIGHT ENGINEERING SOLUTION
Maurizio Govoni from Centoprogetti took care of light engineering and also developed the structural project of the installation.
To keep to the architectural neatness of the premises, the luminaires were positioned onto the ledge that runs along the perimeter of most display rooms. For the rooms without a ledge, Norlight has fabricated extremely small containers for the luminaires that minimise the visual impact.
According to the light engineering project, the lamps should meet the following requirements: good colour index, low heat emission, low consumption and good light efficiency, dimming option. We chose a fluorescent compact light source with a colour rendering unit 1A. After a few tests, the 3800 K colour shade was selected.
The appearance of the luminaires was not a priority given that they were installed onto the perimeter ledge or inside the special containers. Instead, their technical features, such as component quality, ease of installation and maintenance, were essential.
The luminaires installed are BLAe type with two lamps and asymmetrical reflector, in the special version with a 0-10V dimmable electronic ballast that guarantees an optimum flux and illuminates also very ample rooms.
To minimise exposure of works to light, we designed and manufactured a body detection system that raises surface light density in the room when visitors come in. After approximately 15 minutes that no one is in the room, lighting drops to a 'rest' value that is roughly 20% of the standard value. This is feasible since the luminaire selected accepts instant changes of the flux emitted.
Light increasing only in the presence of visitors not only guarantees lesser exposure of works, but also obviously positively affects electricity consumption that can be cut down by approximately 50%.
Using this system, linear control of surface light density in the single rooms is possible, independently of other rooms.
Preliminary tests had already highlighted excellent system flexibility that guarantees adaptability of the amount of light depending on expectations of the Culture Bureau for the single rooms. Subsequent adjustments, if required, are also possible should paintings be changed or the visitors' sensibility be evaluated differently. |
