The project sits on the edge of the Serra de Collserola, in a suburban setting in direct contact with nature and a communal garden. A CFD analysis of the local climate and prevailing winds underpinned the environmental strategy from the outset, shaping an open, extroverted volume (ground floor + 5 storeys with 30 dwellings) wrapped by continuous perimeter terraces. The square plan (24.5 × 24.5 m) is organized in concentric bands, with living-dining rooms and bedrooms on the outer ring and kitchens, bathrooms and circulation on the inner one, producing compact, corridor-free dwellings. A central atrium drives the building's passive ventilation. The CFD study confirmed it was essential to guarantee cross-ventilation across all typologies —including a single-orientation dwelling that depends on the atrium to breathe. The atrium operates with a dynamic form factor: closed in winter by an atrium-like roof element that turns it into a sheltered, collective bioclimatic space, and opened in summer to establish a constant draught that helps the dwellings evacuate excess heat. Diagonal routes and crossed views reinforce daylighting and the visual connection between interior and garden. The perimeter balconies were studied in detail for solar radiation: their horizontal surfaces are shaded so that, in practice, they perform as protected extensions of the living spaces, widening at the corners into usable terraces. The thermal bridges generated by the cantilevered balconies were analyzed and resolved to preserve the continuity of the envelope. Now occupied, the dwellings show very good bioclimatic performance and high levels of user satisfaction, confirming the strategies developed during design.