Authors’ CommentMendeleev 5, a structure that remained unfinished for nearly a decade, is redesigned as an energy-efficient office building. The building is wrapped in a high standard thermal insulation envelope, doubled on the East, South and West by a secondary filtering golden facade that contrasts with the gray fiber cement background. Between the two layers of the envelope are included walkways - accessible to those in the building. The glazed areas are made in modular technology (unitised facade) and include motorized windows that contribute to ventilation and passive cooling of the spaces. The original project includes a combination of intelligent advanced technologies integrated both in the envelope and in terms of internal equipping - with a hybrid air-conditioning system architecturally designed and integrated. The thinking of architects was centered on the user's ease and ergonomics but also the subjective comfort of the building occupants. Thus, the space is extremely flexible allowing 100% cellularisation - each resulted office having access to natural light. The project includes green terraces and a top floor terrace of 300 sqm, free of equipment, offering a unique panoramic view over the center of Bucharest.