A project for the integration between natural light and artificial light.
1997 saw the start of a series of studies on the lighting of the Museo de Bellas Artes (Museum of Fine Arts) in Cuba housed in two different buildings featuring differing architectural characteristics.
Characteristics of the buildings
The museum consists of two distinct buildings: one is the Museo de Bellas Artes, is contemporary in style and dates back to 1954 and features international style characteristics. It will only house Cuban artworks. The building has the following characteristics: Total surface area: 3,460 sq. m (Length of the display trails: 240 m - height of walls 4 metres).
The Asturian Centre is the second building is on the other hand a typical La Habana Eighteenth century building. The premises will house paintings (from the Fifteenth to the Nineteenth Century), Egyptian finds, fabrics, a collection of Greek ceramics and glass panes belonging to former private collections. The Asturian centre has the following characteristics: Total surface area: 5,000 sq. m.; Height of the premises: from 4 to 5 metres.
The object, the requirements
For the Museo Nacional de Bellas Artes, a correct distribution of natural light was necessary to create uniform diffused lighting and to avoid damaging the works of art with direct exposure to light. The distribution of the collections on the different floors was established by Cuban art experts. Their request was to use natural light to illuminate the oldest works as much as possible. And the oldest works are exhibited on the top floors of the building. Given that this setting was a museum, the luminaires had to comply with several requirements: discretion, so as not to distract visitors’ attention, and practicality, meaning easy mounting and dismounting to facilitate maintenance operations.
In addition, the lighting system had to be extremely flexible to adapt easily to temporary art exhibition settings.
Several tests were carried out to obtain maximum 200 lux and average 150 lux illumination values on the vertical plane. The aim was to integrate artificial light with natural light only in those areas where this was possible. Artificial lighting was of course used in areas with no access to sunlight, due to the special architectural structure of the building.
The exhibition halls of the Museo de Bellas Artes are arranged both along the north/south axis and east/west one. The inclination of sunrays on the façade at 12 noon ranges from a max 90° in summer to a min 40° in winter. Windows facing east and west receive of course a much higher amount of natural light compared to those facing south. In winter, the north/west wing never receives sunlight, while in summer, from 4 p.m. onwards, rays have a 40° incidence. The south/east wing, instead, also receives sunlight in winter.
The lighting project was based on the creation of a barrel semivault with particular curving near the windows that are concealed from to the visitors’ view.
The particular curving prevents natural light from the windows from impinging on the artworks directly. Light is deviated instead towards the white walls.
The curved ceiling was painted with white diffusing paint with a tantalum dioxide content in order to improve the absorption of any residual ultraviolet rays. Window panes in fact only filter radiation below 400 nm. Sella fluorescent systems with asymmetrical optics were installed along the “luminous groove” created at the foot of the windows along the lines of the internal cornice. At night these fittings illuminate the vault and recreate daylight conditions. A sensor was installed at the top of the semi-vault, near the wall. It detects the illuminance values on the semi-curved ceiling and sends data to the control system. Based on a predefined scale of values, the control system adjusts the quantity of artificial light needed to obtain the desired effects.
The Museum areas that did not require integration of natural and artificial light were instead lit with a system adjusted manually both during the day and at night.
Some recessed fittings were fitted into the false ceiling opposite the walls. These fittings house different light sources, such as: T16 3000K fluorescent lamps, very low voltage halogen lamps with dichroic reflectors and very low voltage halogen lamps.
The refurbishment strategy for the Museums was devised by the Consejo de Estado which, in Cuba, is also in charge of carrying out the refurbishment work.