ZIN in No(o)rd

“ZIN in No(o)rd” is located in the heart of the Northern Quarter in Brussels. Central to the project is radical re-use. Instead of a simple restoration of the existing two towers, a volume of 14 double-height floors is inserted in-between, creating a “horizontal high-rise”. Offices, apartments and a hotel alternate with each other, creating a true hybrid building that is active 24/7. Two lower public volumes counteract the high-rise and activate the building towards the direct neighbourhood, while the public roof garden on the 29th floor works as a soft landmark on the skyline.

ZIN represents a cutting-edge example of hybrid design, combining a range of functionalities within a single high-rise structure. This mix of uses is key to transforming the Brussels North district into a dynamic, multifunctional environment. A central aspect of ZIN is the creation of a flexible, adaptive scheme, capable of accommodating various uses over time. This is realised through the architectural concept called ‘Zebra-scheme’ in the high-rise, while inserting lower volumes on street-level with public functions. Rather than isolating the different functions into distinct, segregated floors or volumes (as is common in many mixed-use buildings), the Zebra Concept interweaves them. The floors alternate between office spaces, residential units, and hotel rooms, allowing for maximum flexibility in the use of the building. A key challenge but also driver for this concept was the limited floor-to-floor height in the existing towers. To address this problem, one of the most striking features of ZIN is the “Volume Capable”, a central double-height space designed to connect the two towers. The flexible nature of this volume ensures that, as the building evolves, it can accommodate the changing needs of its users.

One of the most significant challenges of ZIN was determining the feasibility of repurposing the existing structure. The WTC I and II towers, built in the 1970s, had been designed to meet the standards of their time, which are far different from those required today. The project began with a comprehensive structural diagnostic of the existing building. After careful consideration, the team considered that the optimal approach to maximise material reuse while addressing the structural constraints of the existing building was to preserve the structural cores and basement levels, but not the light floor slabs of the towers. This resulted in a peculiar set-up of adaptive re-use, with only the two 30-floor cores standing above-ground at a certain point. Nonetheless, this concept aloud to retain approximately 85% (171,000 tons) of the original structural mass. The preservation of these elements alone accounted for over 70,000 cubic meters of concrete. Thus, the project significantly reduced the need for new materials, minimizing waste and environmental impact.