ZIN – a layered ecosystem in the middle of the city

The ZIN project transforms the former WTC I and II towers in Brussels’ North District into a hybrid complex combining offices, residences, a hotel, retail spaces, and sports facilities. This large-scale repurposing project serves as a model for sustainable and circular urban development, with a strong focus on reuse, flexibility, and ecological integration. The central office section, the Marie Belpaire Building, accommodates 3,900 Flemish civil servants, making it the main administrative hub of the Flemish Government.

As part of this ambitious project, Plant en Houtgoed designed the green spaces and vegetation strategies for all parts of the building and the surrounding public areas. From a 12-meter-high greenhouse to a rooftop garden at 90 meters, from indoor planting on office floors to a green façade structure – together, they form a mosaic of habitats that reinforce and expand the connection with the surrounding green network.

Rooftop Garden at Altitude

The rooftop garden at a height of 90 meters – one of the highest in Belgium – was designed as a robust habitat based on maritime and pioneer species with high wind resistance. This specific planting concept aligns seamlessly with thermophilic urban vegetation types and demonstrates how, even under extreme conditions, a biodiverse and visually rich garden can emerge with a core of native species.

Entrance Greenhouse

The 2,000 m² greenhouse functions as a green oasis in the stony North District. A multi-generational planting of trees, shrubs, and a diverse herb layer creates a sheltered ecosystem that invites rest and experience. Thanks to an informal path structure and the use of species with sensory qualities such as scent, color, and texture, an immersive nature experience arises in the heart of the urban fabric.

Office Floors

The vegetation strategy for the office floors uses a dual approach: a permanent ‘young forest’ embedded in the flooring and a ‘mobile forest’ in pots that evolves with the needs of both users and plants. This layered approach makes the greenery functional and adaptable, improves the indoor climate, and ensures that nature is visually present at every workspace.

Green Façade

The green façade was deliberately designed with a low-tech approach using deep substrate containers on each floor. This allows for the integration of larger shrubs and robust perennials. With pioneer species such as trembling aspen and white poplar, a living green veil emerges over the years, activating the façade both ecologically and aesthetically, with minimal irrigation requirements.

Public Space and Greening

The outdoor space around the ZIN complex is being de-paved and restructured with a layered vegetation structure that extends the greenhouse ecosystem down to street level. This results in biodiverse urban biotopes that are woven into the public domain and contribute to the greening and climate resilience of the North District. ZIN proves that nature-inclusive construction is possible on a large scale. The project unites functionality, sustainability, and experience in an ecosystem deeply rooted in both the urban network and the lived experience of its users.

50.86135136341368, 4.357323914186734