In the construction of transparent building envelopes, next to the structural and building-physics solutions, the concept for ventilating the building interior plays a decisive role. While, on the one hand, American office buildings in particular are still ventilated by means of central air-handling plants, in Europe, residents and occupants are accustomed to ventilating spaces by opening windows or other apertures. A mild climate and a high quality of outdoor air are a good basis for natural ventilation. In decentralised systems – in contrast to centralised climate-control systems – operable facade elements are required for the individual rooms. In this way, fresh air can be supplied via the facade – a short path – doing away with the complex, copious ductwork as well as the central plant. Generally speaking, decentralised systems involve simply opening and closing windows; they also have a positive impact on the occupants’ sense of well-being.