The German Sustainable Building Council (DGNB) has completed the refurbishment and extension of its Stuttgart headquarters. As the organisation behind one of Europe's most demanding building certification systems, the project serves as a practical reference for sustainable office retrofits. The work included both interior renovation and additional space, though specific technical details on materials, energy performance improvements or certification level have not yet been published. For specifiers and contractors, such flagship projects typically demonstrate how sustainability standards translate into real-world construction constraints – including challenges with existing building fabric, budget limitations and operational requirements during phased works.