The MAC’s, the contempory arts museum of the French community of Belgium, conceived by the architect Pierre Hebbelinck, is a renovation project made in the ruins of a factory site. This ruin, the old coal mining of Grand Hornu, Belgian equivalent of the Royal Saltworks of Arc and Senans of C.N. Ledoux, is of neo-classic style.The project consisted of the renovation of a building named « the house of the engineers » and the building of two new rooms called the “bridge” room and the “square” room.

The architects and the project owner wished to favour the daylighting penetration while providing a great protection to the works of art.  This protection is again the ultraviolet rays and against housebreaking.The four rooms are placed one behind each other and have different orientations.  They all were studied under artificial sky (mirror box) and artificial sun in order to choose the best daylighting solution according to the needs of each room, under their different constrains.

The architects decided to treat differently the showrooms and the connecting spaces; the showrooms are introverted and do not have direct view to the outside while the connecting spaces establish the link between the museum and the outside.  This link is made by lateral view windows that allow the visitor to locate himself in the site. The artificial lighting has also been studied very accurately in order to make it the more complementary as possible to the daylighting; the luminaires are hidden and the walls colour has been studied in order to make the natural and artificial light the more uniform as possible.The two first rooms, localised in the « house of the engineers », have a listed south oriented façade.  The direct daylighting supply is very high and it was impossible to modify the façade.  The architect has chosen to build a second skin, set back from the existing façade and made up of a translucent glazing highly diffusing, that stops any direct radiation that could come in the room.The third room, called the “bridge” room, is lighted by two longitudinal skylights that are only broken by a structural beam.  The daylighting come thus into the room by the roof and is distributed by reflections on the vertical walls.   The last room, called the “square” room, is lighted by north oriented rectangular sheds.The on/off electric lighting schedule has been established according to the seasons.  That allows consumptions reduction during mid-season and summer.