1+1=1 is the – not strictly correct, but significant – mathematical formula adopted by the l’Escaut group in their approach to the extension of the Charleroi Photography Museum. Taking that formula back to the concrete terms of the recently completed project, it may be intuitively translated as: pre-existence+new=unity. The pre-existence is an ancient Carmelite brick convent that had already housed the museum since 1987; the new is a modernist wing with a deep projection and curious cladding, similar to a bar code but softly coloured; the unity is the resulting continuity, and the new spatial scenery created by the whole construction in harmony with the surrounding park.

Going back to the bizarre algebraic sum, its freedom reveals the imaginative and creative strength of the project team, whose work is nurtured on a broader range of disciplines. Young architects today increasingly often display a highly receptive outlook, for every research project or commission undertaken, in cultural operations that bring together assorted disciplines and fields of interest with equal dignity. When the Belgian office l’Escaut opened in 1989, its philosophy was that architects and planners should work closely, in a climate of civilised commitment, with interpreters of the performing art – such as actors, directors, stage designers – and, where necessary, with anthropologists, artists and landscape designers. The extension of the Photography Museum entailed a six-month programme to enable the office to establish the concatenation of spaces and functions that connect the existing building and its new wing, in a domino effect.

The scenic accent impressed on the work guides its architectural solution, while stating in very clear and decisive terms its interconnection with the age-old surrounding garden. The broad C-shaped cantilever described by the new building – with an innovative structure of solid wood panels – not only leans out with fine proportions towards the garden, but also draws it in and embraces it. The precise geometry of its volumes takes on a twofold quality, as a well-articulated spatial construction and as an interface between the park and what was there before. The effect of echoing the surroundings is also entrusted to the artist Jeanine Cohen, whose work covers the 900 metres squared of the extension’s frontage. Her thin aluminium sections of irregular dimensions, densely and vertically clustered, afford glimpses of a pastel-coloured surface in the background that changes according to the natural light. Besides lending buoyancy to the frame, this vibrant outer shell relates to the theme of the institution – which holds a collection of 80,000 photographs and 3 million negatives – by putting the building into a state of permanent “photocomposition”.