The interactive complicity between this building designed for use as a library and the surrounding public space characterises this project, where functionality and expressiveness play a basic role in a framework of environmental respect.
This building that, as a freestanding piece, contributes to the configuration of an urban space in the dense fabric of Barcelona's Raval district is placed against a virtual grid that, superposed on the district, arranges all the buildings designed for use as public facilities, establishing among them a subtle relationship of scale and functionality.
The interior space is organised by two structural centrelines running parallel to the façade of the square. The one facing the access, on calle Montalegre, features "domestic"-type lighting characteristics, occupying with its façade the entirety of the four floors plus a fifth one designed to house the air conditioning installations on the roof. This part of the building holds the vertical circulations, services, offices and small computer classrooms.
The centreline that faces the Torres Clavé gardens is designed as a single four-level space, alternately housing the reading rooms in the manner of platforms, in such a way that the global vision of the library is not lost at any time. The union of the two centrelines is formed by a succession of shelves that determine the fourth façade of the reading space.
The façade giving on to the square consists of a large curtain wall formed by two leaves. The external glass contains a metallic fabric made from brass and copper filaments that reduce solar radiation by 50% while emitting gold reflections that change according to the angle at which they are struck by sunlight. The internal translucent glass face blurs the natural light, preventing any inconvenient shadows when reading. Inside the double skin are the artificial light diffusers that transform the façade into the only source of light for the square.
The perforated prefab concrete panels that close off the rest of the building perform the function of providing a solid and compact appearance, reinforcing the singular character of the library by eliminating any possible windows that may be likened to a residential scale and acting on the interior like a lattice that allows natural light in.
Access takes place via a single perforation opened in the north-eastern façade that in turn breaks up its solid volume at ground-floor level. It constitutes the focal point that invites users to enter, displaying the library interior reinforced with the presence of a great window-sign. The unevenness between the access and calle Valldonzella is bridged by a ramp formed from the "fold" in the paving of the plaza-atrium, which arranges and systematises the approach to the building.
The library has two underground floors in order to house the parts of the programme that require special conditions of height and insulation, such as the auditorium with seating capacity for 205 people and the television "set".