Radisson RED

With its tectonic façade fold, the first Radisson RED Hotel in the German-speaking world forms a new architectural focal point in what is currently probably Vienna's trendiest multicultural district between the city center and the Prater - including a view of the old town of the Austrian metropolis on the Danube.

This is of course also due to the expressive façade. Its design comes from the multi-award-winning Innocad architects from Graz and interprets Radisson's philosophy, which aims to appeal to Generation Y with the RED brand. This appears to have been successful, as Oliver Kupfner and his project team reached the finals of the Hotel Design Awards 2022 and the Plan Awards 2022 for The Rock. The architects also impressed the judges of the European Property Award 2022-2023.

Consistent façade concept

The façade of The Rock moves beyond the usual geometric design language. It is not only the name that reminds us of geological structures that are characteristic of the Alpine republic. Local associations can also be felt in other parts of the architectural concept. On the one hand, this building envelope meets all the requirements of the building regulations, while on the other hand it harmonizes visually with the building's surroundings and continues the historic perimeter block development. This consistent façade concept extends right up to the roof terrace with its adjoining garden. This can be seen very clearly from the inner courtyard. Incidentally, this is already visible from the street through the transparent first floor, which gives the first floor level an airy lightness.

A 24-metre-high graffito in the inner courtyard forms another visual anchor of the building. Above this, three interconnected glass houses on the publicly accessible roof terrace appear to float above the building. A light textile ceiling stretches like a tent over the Skybar and echoes the basic architectural idea inside.

Safety glass as a base

The entire façade consists of folded diamond-shaped aluminum elements. They give the hotel its name-giving stone-like appearance. This structuring building skin is only interrupted by gold-bronze mirrored windows, whose regularity creates exciting counterpoints to the façade contours. The windows, which are shaped as a bench on the inside, protrude from the façade in relief. For the glass, the planning office opted for triple insulating glass made of single-pane safety glass (ESG-H) from Isolar in Klagenfurt with a thickness of eight millimetres on the outside. The abbreviation H indicates that the glass was subjected to a heat-soak test at around 290°C after the manufacturing process. During this test, nickel sulphide inclusions can be detected, which could cause the panes to break when exposed to heat. If no inclusions are present, spontaneous breakage - for example when heated by sunlight - is unlikely. The test is therefore an additional quality control.

Color-coordinated sun shading

This window system is fitted with sunbelt® gold from arcon® in Feuchtwangen as partially toughened laminated safety glass (VSG/TVG 44.2 N10). One reason for this choice: “sunbelt® gold can be precisely matched to the overall appearance of the building envelope or the façade elements used thanks to its special reflective color,” explains Leo Lacroix, Project and Façade Consultant at arcon® Glas. Due to its low total energy transmittance, sunbelt® gold is particularly popular when the visual harmony of the building needs to be preserved and the building's energy requirements reduced. For example, the façade of the University of Innsbruck or the 37-storey Gold Tower in Dubai's Jumeira Lake Tower district, which is named after the sunbelt® gold solar control glass used - or the Radisson RED.

Reduced CO2 footprint

Of course, in summer the glass ensures that not too much heat gets into the interior of the building. In winter, however, the additional requirement for the glass is a high level of thermal insulation so that it remains comfortably warm inside the building. In other words, the air conditioning system consumes significantly less energy in summer and the hotel can save on heating costs in winter. The sunbelt® glass therefore helps to reduce the building's CO2 footprint. In addition, the increased light transmission of the spectrally selective glass on the sides facing away from the sun contributes to the increased well-being of the hotel guests. In addition, the sunbelt® gold glass is characterized by its neutral transmission color with low external and internal reflection. The occupants of the hotel's 179 rooms can also benefit from these properties - and not just during the hours of sunshine. Incidentally, there are more than 2,100 of these on average in Vienna each year, more than in Lyon.

The Rock also has an event room, a public rooftop bar with terrace, a restaurant and a fitness studio. “In total, we have installed around 2,500 square meters of glass in Vienna,” says Lacroix. The lead time for the project was commensurate with its size: “Innocad first contacted us back in 2019. We then held several discussions on site to jointly determine the optimal product for the façade.” However, the arcon® team was not alone in the project

Client	Immovate Realita Group, Wien
Architect	Innocad Architektur ZT GmbH, Grazbachgasse 65a, 8010 Graz
Glass supplier	arcon Flach- und Sicherheitsglas GmbH & Co. KG, Industriestraße 10, 91555 Feuchtwangen

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