Bank building, Bilbao

Bank buildings have an understandable preference for a clear separation between the public area and the private workplaces, a fact that informed No.MAD's design for the bank owned by the Spanish Architects Association, in Bilbao. Banks also tend to be located on just one floor of a larger building but in this case the bank is spread over two levels. The public area and the main offices are located on the ground floor while the more private spaces – conference room, archives, a coffee room, toilets and some storage areas – are situated in the basement.

On the main floor the separation between clients and bank employees is provided by borosilicate glass tubing, a material most commonly used for test tubes in the pharmaceutical industry. The visual distortion caused by its convex shape provides both privacy and translucency. In this way, Eduardo Arroyo – No.MAD Architects' principal – has come up with a bright solution to the main problem of this project namely, how to allow natural light to penetrate the office area without exposing it to the gaze of clients, while at the same time that the creative potential of working with materials that are not specific to architecture.

The geometry of the glass wall was determined by the position of three big freestanding pillars, which were incorporated into the workspaces and hidden from the public's view. The differentiation between spaces is further reinforced by the use of different colours: black in the public area and grey in the workspaces. These two separate worlds meet at just two points: the public service counters and the stairs leading to the lower floor. The dual colour scheme also contributes to the sense of mystery evoked by the materials, shapes and geometries of the space.

Another positive feature of this design is the very restrained glass facade. All that is visible from the street is a single opaque door flanked by two small, glass-lined recesses planted with bamboo (behind which we can vaguely see that there is something on the lower floor). This neutrality is dictated by the idea of functional flexibility (there is nothing that shouts 'BANK') and by the desire to provoke doubt and curiosity – a recurrent theme of No.MAD's design and theory.

Aware of the architect's growing responsibility for 'building' a better world, but without ever losing the academic drive to experiment, this group of architects has managed to make its mark on the Spanish architectural scene, thanks to their perceptive understanding of contemporary reality. By questioning everything – What is a bank? What is it for? How does it work? How should it work? Why does a bank have to look like a bank? – rather than accepting standard 'truths', No.MAD managed to find intelligent responses to the programmatic and spatial challenges confronting them. The use of a translucent material is a practical and metaphorical solution to the need to separate without excluding.