For a lengthy period, the Westraven office building in Utrecht was a heavy, closed and stuffy colossus that was on the verge of being demolished. The eventually preferred revitalization aimed at reflecting the modern values of user Rijkswaterstaat (department of Public Works): openness, transparency, professionalism and sustainability. The proposals advanced by cepezed harmonized best with this goal.
The high-rise section, accommodating more than 27,000 m2, was stripped down to its concrete skeleton and equipped with five enormous voids that introduced much daylight and spatial experience into the building, and also contribute to good orientation. The new façades are largely made of glass to allow a panoramic view and abundant incidence of daylight. Sections that can be opened enable natural ventilation. A second-skin façade of mainly teflon-coated fibreglass mesh prevents wind nuisance, functions as a sunbreak, leaves the view intact, and also forms an aesthetic component that imposes a strongly horizontal articulation. The renewed climate system consists largely of project-specific climate ceilings between the concrete floor beams.
At the foot of the high-rise, an extension measuring 23,000 m2 contains five triangular office wings that offer a view of the adjacent canal to as many rooms as possible. The triangles are linked at the basis by means of an efficient traffic aorta and at the rounded tips by a large, encompassing conservatory in which the spaces between the wings have been roofed over with transparent material.
With a water basin surrounding it, the complex in embedded in a park-like environment of around 3,000 m2.
The ensemble has a great variety of sustainability-related aspects. In addition to the second-skin façade and climate ceilings, there are also underground warmth and cold storage, concrete core activation in the new-construction floors, a division into various climate zones, and a series of integrated design solutions that are not only aesthetic and functional, but are useful in terms of material saving as well.
Westraven has been nominated and has received many prizes for both its architecture and its commitment to sustainability.