Completed in 1999, this 375,000 sf complex houses nearly 1,000 employees in four L-shaped buildings defining a central lawn, with open legs oriented both north-south and east-west. A fifth building includes reception, gymnasium facilities and restaurants. An exterior running track and athletic courtyards are included in the site development, along with parking under the central lawn area. Utilizing a variety of sustainable features, such as ground source heat pumps, roof-collected storm water for flushing toilets and irrigation, natural ventilation, and certified wood, the building is one of the most energy efficient offices of its size in the Netherlands.

The building section is thin (60 feet in the east- and west-oriented offices and 41 feet in the north-and south-facing offices), influenced by the Dutch practice of keeping office workers no more than 18 feet from an operable window. Safety guidelines (ARBO) required, in this case, that daylight apertures equal or exceed 5 percent of the workfloor area and that the width of the apertures providing outdoor views equal 10 percent of the workfloor dimensions. Another consideration in the use of a narrow floor plate is a long-term sustainable building program anticipating future conversion of the office space to residential space.

Northwest view of office buildings from central lawn		Typical Office Plan

Loisos+Ubbelohde worked with the architect to evaluate office daylighting options using Radiance simulations for sun penetration, illumination levels and visual character. This project differed from typical United States office projects in that the sky conditions in the Netherlands are predominantly overcast. The design strategy opens the office floors to available daylight while allowing occupants to lower blinds as necessary on unusually sunny days. The north roof is lifted to nearly double the ceiling height on the top floor and is prepared to receive a photovoltaic array in the future. Taking further advantage of the top floor, clerestory monitors with east and west glazing pierce the roof over the central office areas, ensuring a fully daylighted floor in each building. Daylighting is well-coordinated with the use of Philips individually sensored and controlled dimmable fluorescent fixtures, ensuring that the system makes the most of any daylight reaching the workstations.

Fourth floor office with double height curtain wall facing north		Office section with illumination levels from physical model testing in artificial sky

Ground floor daylight access is more limited than on the upper floors not only because the view includes more lawn and buildings than sky, but also because it is further reduced by a covered path linking the buildings facing the central lawn. Comparative Radiance simulations helped determine that daylight to the ground floor offices could be maximized by making the coverings as transparent as possible and the ground surface light and reflective.

Walkway canopy as built	Walkway canopy alternatives rendered in Radiance

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The campus buildings were massed to ensure narrow floorplates that would enable daylighting and views.

Overhang sizing balanced the need to reduce glare from direct sun while recognizing the importance of sun in such an overcast climate.