Blood centre, Porto

ARX is derived from ARchiteXture, which is itself a conflation of architecture, text and texture, a non-hierarchical territory in which each element is totally ambivalent. More than just a vague concept, it is the central idea behind the work of the ARX Portugal Arquitectos (José Mateus and Nuno Mateus): architecture of investigation and experimentation, of questions rather than answers. This approach is clearly demonstrated by their most recent work, the Porto Regional Blood Centre (CRS). Confronted with confused and degraded surroundings, ARX Portugal created its own references and its own context.

Unsurprisingly, the first feature to be retained is the way the building appropriates the site, as an irregular polygon. One of the first concepts exhibited a single, long side constructed as a continuous line that, in a series of folds, dominated the whole perimeter, thereby creating its own geometry. That intention was not confined to paper. As one approaches the finished building, one's first impression is of horizontality and linearity. The shape, as is usual in the work of ARX Portugal, is arrived at in a constant dichotomy of stability/instability, in a search for tensions, rhythms and breaking points. There unfolds an exciting game between mass and emptiness, heaviness and lightness, opaqueness and transparency, which never loses the initial sense of unity.

It cannot be said that this approach to place is conventional. Instead of giving in to the easy temptation to forget the rather unattractive surroundings, the architects have no qualms about relating them to the building. At times the building appears to hover above the ground, generating areas of permeability that correspond to the entrance areas. The garden acts as a mediator between the building and the surrounding area, separating it from the other buildings, creating an area of romantic abandonment where creeping weeds will mark the passage of time. In the interior the long, narrow, horizontal windows filter visual contact, outlining and de-contextualizing it.

The series of openings and the layering of different raw materials emphasize the horizontality of the building. Each of the different materials contains its own logic: the local granite with which the building makes contact with the ground, the galvanized steel cladding, the industrial glass in the windows, the zinc roofing and the plywood cladding.

The formal linearity of the building corresponds to a functional linearity and is appropriate to a project involving the sequential process of collecting and analysing blood and the sub-division of its components. A naturally complex topology, very recent and hardly tested, presupposes the constant adaptation of new procedures and technologies. This demand is reflected in the interior spaces, which are undetermined and open to changes over time. For the same reason the interior is sober, showing a continuity of materials, although not avoiding the use of a more plastic manipulation of shapes that is aided by the careful way in which light is treated in the interior of the building. Light is constant, but filtered through bands of 'murolux' glass, which capture, reduce and disperse sunlight from sunrise to sunset. As in all of ARX's work, the pragmatic resolution of the programme goes hand in hand with clear formal investigation. There is a search for a poetic dimension, something that ARX interprets as essential in architecture.