In collaboration with VK Engineering One of the most innovative office buildings designed by architect Leon Stynen is located above the underground north-south railway connection in the heart of Brussels. When this building was completed in 1958, it was a technological tour de force, but 50 years later, it needs some adjustments. Although it is not classified as a monument, it was soon decided to clean restore the facade to its original appearance where needed. All the engineering and fittings were replaced and once more, architects looked for the latest visions regarding sustainability and energy management. The box-in-the-box principle makes it possible to optimally insulate the walls and make spaces that are independent of the existing wall structure. The concept received the energy reward from the city of Brussels.