Collaborators: Sara Rojo, Pablo Cruz, Carlos Tomas
Quantity Surveyor: Jose María Rife Beltrán
Structural Engineer: Jorge Conde, IDEEE
Services Surveyor: Manuel Aranda
A manufacturer of electronic security systems wanted a “unique and bioclimatic” building for its new headquarters in Alcalá de Henares northeast of Madrid. Alarcon Asociados came up with a design in which (expressive) form and (climatic) function work hand in hand. That the client is also the owner of the building might explain their boldness in endorsing such an unconventional design.
Towards the top of the building, the red coloured in-situ concrete slabs cantilever increasingly farther out. They reduce the direct solar gain on the facade by about 90 %, making movable blinds unnecessary. In this building for the first time the architects used a self-developed HOLEDECK floor system with integrated hollow spaces in which all building services could be routed. That saves around 50 cm of building height per floor, because suspended ceilings were not needed. With their enormous spans of 12 metres between the piers and their almost complete symmetry, which is only disturbed by the outdoor stairs on the southwest facade, the 1000 m² office floors can be arranged without restrictions. The stick system facades made of timber have a glazed percentage of 50% and opaque spandrel panels with 100 mm mineral wool insulation. On the exterior, these are faced with 0,8 mm gold-coloured anodized aluminium and on the interior with oak panelling.
Particular to this building are the diagonal buttresses on its centre lines and corners which continue upwards in powerful piers with V-shaped cross-sections. All vertical air ducts, as well as the heat exchangers for the intake and exhaust ventilation, are contained within these structures, which Alarcon Asociados call the “noses” of the building. The intake air is drawn in from above the roof, then sent underground through eight earth pipes (one per pier, each 180 metres long) and finally back through the piers to the office levels. The exhaust air also flows through the piers and then out over the roof. Due to the preconditioning of the air and the automatic nightly cross ventilation, no conventional air conditioning system was needed. To heat the rooms, the concrete floor slabs can be thermally activated by means of inlaid piping. Heat is mainly provided by solar collectors on the roof, with a gas boiler serving as back-up system.
The architects calculate that the building consumes 40% less energy for illumination than a conventional building. The absence of moveable blinds and the shading provided by the cantilevering concrete floors, they say, should help minimise the use of electric light during daytime. Artificial lighting is provided exclusively by LED-luminaires with a basic lighting of 200 lux, but the brightness can be increased directly at workspaces to 500 lux if needed.