One of the design challenges for Grontmij was to locate all main mechanical plant on a limited roof top area with restricted height. To accommodate the plant on the roof, the building used a direct gas fired burner in the fresh air-handling unit to heat outside air during the winter months. The highly insulated office areas utilised perimeter electric heaters for the relatively small heating needs, which will only operate during periods of low occupancy. As a result the building achieved a “very good” BREEAM rating.