Central Idea • Collecting and preserving documents and artifacts is as old as humanity itself. This practice reflects the desire and need to document one’s own history to make it legible and understandable for future generations. For the Swiss Federal Archives, archiving the records of the Federal Assembly, the Federal Council, the Federal Administration, and foreign representations means nothing less than contributing to legal certainty and making governmental actions comprehensible. The central idea of the design places the importance of the building envelope—as a separating and protective element—and the transitional space between exterior and interior at the heart of the urban planning, architectural, and functional concept. Urban Planning and Architectural Concept • The new Federal Archives building is conceived as a highly compact structure with an optimal envelope-to-volume ratio. Taking full advantage of the building regulations, approximately 40% of the volume is above ground and around 60% is below ground. Through its orientation and dimensions, the above-ground portion of the archive complements the urban ensemble of the new federal buildings in the Meielen Nord development area. The design theme of the building is derived from the protective nature of the building envelope. The structure presents itself as a largely closed, static volume, with its mass articulated into a base and a roof area by the integration of photovoltaic elements. Solar Energy Concept • The integration of the photovoltaic system becomes the design motif of the building. Not only the roof, but all façade surfaces are clad with PV elements. By tilting the panels for better energy efficiency, the technical system becomes an integral part of the building’s overall aesthetic. The inclusion of the façade surfaces not only exceeds the building’s own energy requirements but also ensures energy autonomy during the winter months, on a monthly basis. The roof panels are made of PERC monocrystalline silicon shingled modules. This PERC shingled technology is characterized by ultra-high efficiency and improved performance under low irradiation conditions, increasing electricity generation during winter. The façade PV panels consist of colored glass-glass modules in which the PV cells are invisible. The pigments provide a rich coloration with high transparency, optimizing light absorption by the solar cells. Climatic Requirements – Storage Zone • The archive’s storage zone must meet specific climatic requirements. In addition to examining the ideal building shape—featuring a minimal envelope for a maximum internal volume and an optimized static system—several simulations were carried out using various construction materials. As a result, a single-shell insulated concrete structure was found to be optimal for components not in contact with the ground, while insulated reinforced concrete was best suited for components in contact with the ground. This approach proved more effective than timber or clay alternatives in maintaining the target temperature and humidity range without additional ventilation. The temperature curves below illustrate that only the top floor requires supplemental heating via ventilation. To maintain the required humidity setpoint, a small full air-conditioning system is used, with individual zones for each archive level. Through a switchover mechanism, all floors can be conditioned using a single system. An oxygen reduction system is also installed, which lowers the oxygen concentration in the room to reduce fire risk.