The ICTA-ICP Building, on the Universitat Autònoma de Barcelona campus, was conceived as a research infrastructure that performs like a living environmental system. Housing offices and laboratories with high internal heat loads, the design turns those loads into an asset in winter and dissipates them in summer through an integrated set of passive and low-energy strategies. A robust, long-life concrete structure provides high thermal inertia; its mass is carefully distributed and partially thermally activated through embedded piping and geothermal exchange, stabilising temperatures and reducing peak heating and cooling demand. Around this structure, a low-cost bioclimatic outer skin functions as a controllable greenhouse: automated openings regulate solar gain and ventilation, creating tempered perimeter and interstitial zones that improve comfort without conventional conditioning. Four internal patios bring daylight deep into the plan, cutting artificial lighting and enabling natural ventilation paths. Vegetation in patios, galleries and in-between spaces supports a healthier microclimate by moderating humidity and enhancing perceived comfort. The building is organised as a gradient of climates. Generous intermediate spaces rely on passive behaviour; offices combine natural ventilation with radiant and semi-passive systems; laboratories operate more hermetically where required. Insulated timber “boxes” sit within the tempered volume, providing efficient, adaptable workspaces while leaving flexible interstitial areas for circulation, informal meetings and rest—spaces that can evolve as research needs change. Basements contribute to environmental performance by using ground contact to pre-condition fresh air through ventilated chambers, lowering the energy cost of renewals. Materials prioritise durability and low maintenance, with dry, reversible secondary systems and an emphasis on recycled or bio-based components where appropriate. Water strategy closes loops by reducing demand and enabling reuse streams—rainwater, greywater and other treated flows, so the building’s operation aligns with the circular resource logic of the research it hosts.