This project is a complex and large-scale combination of existing buildings and new construction for various departments of the Dutch 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 existing high-rise construction has been completely renovated and reorganized. An elongated four-storey building has been realized around the foot of the building. Façades made entirely of glass and voids in the floors give a strong impulse to the spatial experience of the high-rise block, which is rather limited in the original architecture. Atriums, conservatories and inner gardens stimulate unprecedented spatial awareness, and are also important for the orientation of staff and visitors. The various functions of high-rise and low-rise construction are combined at the foot of the tower in spectacular, large, open spaces 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. 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. Various types of space have been climatized differently, the heat of air flows is recovered at several points and the artificial lighting adapts itself automatically to the colour and intensity of the incidence of daylight. Furthermore, a revolutionary feature is the innovative second-skin façade of open-weave, teflon-coated glass fibre that offers all-round protection against the wind and makes it possible to work with open windows, even on the top floors. As a result, the staff enjoy great freedom is regulating their own interior climate, which is quite a luxury for high-rise construction.