Stacked rows of stylized book spines wrap the sinuous walls of the Leganés Norte Central Library in a witty example of architecture parlante. The sign is redundant: Everyone in the surrounding neighbourhood, a new development on the southern edge of Madrid, can guess what’s inside.

The outer facade is composed of 9,126 curved terracotta tiles in 40 different sizes and 17 hues, integrally coloured and clipped to a metal frame that’s attached to precast concrete panels 14 centimetres thick. Behind them is a layer of glass-fibre insulation, another void and an inner lining of gypsum board. A lofty glass atrium links the library to the municipal archives — a volume faced in standing-seam zinc that’s almost moody by comparison.

BN Asociados Arquitectos, the husband-and-wife team of Silvia Babsky Nadel and Ramón Valls Navascués, won the job in 2007 by proposing what would have been Spain’s first net-zero building. Photovoltaic panels on the roof provide power, while energy consumption is reduced by the combination of layers in the walls and natural ventilation. Double-glazed windows and blinds are operated by sensors and shaded by louvres on the west side.

The Great Recession halted construction as the building neared completion, delaying it for eight years. Other sustainable buildings have since been completed in Spain, but BN was finally able to realize most of its vision — even though, as Babsky Nadel jokes, “it took longer to build than Philip II’s El Escorial palace.”

It’s a much more useful and welcoming amenity than that chilly monument to absolutism. Though the village of Leganés is centuries old, it exploded into a dormitory town for migrant workers in the 1960s. The library creates a sense of place amid generic housing, serving as a beacon of culture and a gathering place for the entire community.

Spain has a long legacy of ceramics, but the project’s first contractor sourced tiles that broke easily. The architects switched to NBK in Germany, winnowing their original selection of 47 tones to 17, including blue to evoke water and sky, green for the landscaping and sienna brown for the nearby brick houses and the dusty Castilian plain.

Warmer hues were intermixed with these, and an algorithm was used to determine the placement of each tile. The abstract patterns of the facade complement the library’s dynamic forms and attest to the survival of print in a digital age.