The Circle, Zurich Airport, Kloten, CH
The high-tech façade of Switzerland’s largest building construction project, the service centre “The Circle” by the well-known Japanese architect Riken Yamamoto, was realised using the closed cavity concept. The innovative façade construction uses the safety glass GEWE-safe® and the thermal insulation glass GEWE-therm® from SCHOLLGLAS.
Last autumn, an architectural innovation was opened directly at Zurich Airport: With the Circle, the Japanese architect Riken Yamamoto designed his vision of a modern city with a high quality of stay – a building from the outside, a city centre on a small scale on several levels, with alleys, squares and streets, with public and private spaces. The small-scale nature of Zurich’s Niederdorf inspired Yamamoto as much as the proverbial Swiss precision. He translated what he called “Swissness” into the architecture of the Circle.
Switzerland’s largest building construction project, with a construction volume of around 1 billion Swiss francs, refers to the large-scale forms of the airport. The cubature nestles against a hill that is almost circularly bypassed by Flughafenstraße – hence the name “The Circle”. Towards the hill, the form dissolves into smaller formats and merges with the park. On up to eleven floors, there is space for science and research, art and culture, shops and office landscapes, services and health care projects, conferences and congresses as well as hotels. In November 2020, the Circle was officially opened.
Project data
Architect
Riken Yamamoto & Field Shop, Yokohama/JPN
Client
Flughafen Zürich AG & Swiss Life AG
Façade Planner
Atelier P3 AG, Zurich/CH
Neuschwander + Morf, Basel/CH
Facade
Josef Gärtner GmbH, Gundelfingen
Products used
- GEWE-safe® LSG 12/2 (66.2), polished edges, float clear 6mm / PVB foil / float clear 6mm
- GEWE-therm® Thermal insulation glass Ug-value 0.6W/m²K, TVG ClimaGuard Premium2 T 6mm / SZR 14mm / TVG ClimaGuard Premium2 T 6mm / SZR 14mm / LSG 10/2 made of float clear 5mm
Photograph
R. Dürr
High-tech for the city façade
The ambitious construction project is certified with the highest LEED standard and MINERGIE. Both building standards stand for sustainability and a responsible approach to the topic of energy. An essential part of the ambitious energy concept of the Circle is the construction of the glass façade, which encloses all buildings to the outside. It was planned as a double façade in order to use the thermal buffer in the space between them to save energy. This
The façade type was developed by the façade specialist Josef Gartner GmbH from Gundelfingen into the so-called Closed Cavity Façade (CCF), for which, among other things, GEWE-safe® laminated safety glass panes from SCHOLLGLAS were used. For the Circle, Josef Gartner installed 83,900 square meters of his climate-friendly façade construction.
Closed Cavity Façade (CCF)
In the case of the closed cavity façade, the 135 mm deep cavity between the two façade levels is hermetically sealed. The resulting closed cavity is supplied with specially treated air by a central supply system. The dried and purified air is pre-tempered and blown into the chamber with slight overpressure. This prevents condensation from being deposited on the panes. The outdoor climate is monitored by control electronics and the dry air production in the technical centre is controlled accordingly. In this way, energy consumption from heating and cooling in the building can be reduced to a minimum. With its building physics values, the CCF has already set new standards. The closed space between the inner and outer glazing also enables the use of highly transparent glass and wind-independent and highly sensitive sun protection to improve transparency, energy efficiency and cost-effectiveness.
Precision in production
The production of the approx. 8,600 façade elements for the Circle (without fire facades) took place in Gundelfingen, Bavaria. A special production line ensured the highest level of cleanliness and precision in production. This was the only way to guarantee the flawless functions of this special type of façade. On the construction site, the elements were hooked into the substructure and fixed. The glass was stored in a circumferential linear manner as dry storage using specially extruded silicone profiles.
A closed cavity element consists of the outer impact plane with laminated safety glass and the inner thermal insulation layer with insulating glass. For the Circle, Gartner used safety glass panes of the type GEWE-safe® VSG 12/2 (66.2) for the production of the CCF elements, in some cases with special requirements for impact resistance in the P4A version. For the insides of the CCF elements, GEWE-therm® thermal insulation glass from SCHOLLGLAS was used. For the three glass layers, two six-millimetre heat-strengthened glass units in the ClimaGuard Premium2 version and one ten-millimetre laminated safety glass were used.
