At the edge of Louvain-la-Neuve, in the green Cîteaux district, a disused barn and a vacant corner plot stood quietly between city and landscape. Mundo Lab, a client rooted in social and ecological values, imagined more than just another office. They envisioned a space for NGOs, non-profits and social economy actors. A place that belonged to its environment, but also to its community. The barn, a modest rural structure, could not simply be erased. It had to be renovated and meaningfully integrated into the project. The challenge: how to design something radically sustainable without relying on newness? How to make circularity the starting point rather than the add-on? The site held no architectural prestige, but it offered the chance to test what regenerative building could be, not in theory, but in practice.

The project combines high performance with low-tech clarity. A hybrid structure of 75 tonnes of reused steel and cross-laminated timber supports prefabricated, glued rib and hollow box elements made of laminated veneer lumber. The envelope is airtight and highly insulated, reaching Passive House Plus standards through geothermal loops, dual-flow ventilation and controlled daylighting. All systems are modular, visible and designed for disassembly. Reclaimed materials such as bricks, timber flooring, tiles and light fixtures are reintegrated with care. Rainwater is harvested and reused, and the parking zones are reversible. Biodiversity is strengthened through wetland landscaping and green roofs. A 1.35-meter grid structures space, use and future reconfiguration. The result: 65% less environmental impact and a building that translates circular ambition into spatial intelligence.