Westraven is a complex and large-scale combination of an existing building (originally completed in 1977) and new construction for various sections of the Department of Public Works, situated in the Westraven area between the Amsterdam-Rhine Canal and the junction of the A2 and A12 motorways at Utrecht. The program consists of office space, conference facilities, a national meeting center, a communications center, and the Future Center for the Department of Public Works. More than 2,000 people are employed at Westraven.

The existing high rise construction has been completely renovated and reorganized. An elongated four-story building has also been added at the foot of the building, alongside the canal. Façades employing both glass and voids give a strong impulse to the spatial experience of the high rise block, which was rather limited in the original architecture.

Atria, conservatories and inner gardens also stimulate spatial awareness in the transparently constructed new low-rise building, and are important for the orientation of both staff and visitors. The steel construction of the enlargement is entirely made of prefabricated components and assembled in dry fashion on the site. It demonstrates refined detailing and interweaves the conservatories, office wings and atria.

The various functions of high and low rise are combined at the foot of the tower in large, open spaces with inner gardens that invite both a rendezvous and casual encounters. Many of the working areas have been designed as flexible workstations, so that it is possible to work at various places in the building. The typological arrangement guarantees that as many people as possible have a view over the canal and the rural area beyond it.

Much attention has been devoted to realizing perfect equilibrium between low-energy consumption and an optimum working climate. For this purpose, an ingenious climate concept has been developed which makes use of thermally active floors amongst other factors. Various types of space have been climatized differently according to their use, the heat from air flows is recovered at several points and the artificial lighting adapts itself automatically to the color and intensity of the incidence of daylight.

To minimize both visual obstructions and the use of material, the architectural, stability, MEP and construction designs were fully integrated, resulting in amazingly slender material dimensions. For example, the floors have a height of only 30cm (11.8in) and contain all ducts, pipes and cables for installations, data, sprinklers etc. Furthermore, the introduction of an innovative second-skin façade of open-weave, teflon-coated glass fiber offers the high rise block all-round protection against the wind and makes it possible to work with open windows, even on the upper floors. As a result, staff enjoy great freedom in regulating their own interior climate.

The interior is flexiwork-oriented such that the floor plans have varying scale levels and degrees of privacy: ranging from open-plan offices to meeting rooms, conference rooms and a large multifunctional hall, to special silent cellular accommodation. In the atria between the office wings in the new-construction section, various lounges have been laid out with low chairs and tables and abundant greenery.