Roof Top Bar with retractable, switchable glass windows
Bar feeling with variable sun and light protection
Lowering windows in historical steel construction

Krapf AG helps Nietturm bar get more fresh air and a better view


Krapf AG helps Nietturm bar get more fresh air and a better view The Nietturm towers as an eye-catching glass cube on the former boiler house of the Schiffbau site in Zurich. However, the bar housed in it has not always been a centre of attraction due to poor climatic conditions. But the renovation with a project-specific façade has now transformed the Nietturm into an open roof-top bar with a guarantee of fresh air.

Due to the exposed location of the steel and glass construction, there were major problems with overheating and stuffy air in the past. The rooms could only be insufficiently protected against solar radiation and could not be sufficiently ventilated. In order to remedy this situation, only a complete renovation of the glass cube could be considered. However, the transparent character of the building, including the spectacular view, was to be preserved.

Together with the façade specialists from Krapf AG, the lead architect Theo Flückiger from arc Architekten in Zurich redesigned the tower's glazing and windows - as well as unconventional drop fronts - accordingly.

The special lowered fronts can be lowered to the parapet height of 1.2 m in a metal framework. In this way, the room opens up in its airy height to the outside space at the touch of a button. The result is an almost open rooftop bar. The air-lux lowering windows used were custom-made and tested in advance in the company's own workshops. The lowering fronts are operated via the building management system and a fully automatic control system. With the help of an electric drive, they can be moved up and down silently.

Electrochromic glazing

In order to be able to control the amount of daylight and heat entering the building even when the windows are closed, the entire building envelope, including the lowering windows, was fitted with switchable glass of the SageGlass type. The intelligent glass can be electronically controlled to darken or lighten in four stages depending on the weather. In any darkening state, the panes allow a clear view to the outside. Meanwhile, maximum thermal and visual comfort is ensured in the interior of the rivet tower, while energy and maintenance costs are greatly reduced.

Krapf AG installed a total of 20 of the motorised air-lux lowering windows and a total of 170 variable dimmable SageGlass hanging glasses for the new exterior façade construction. In this way, it was possible to meet the functional requirements of the glass construction and still retain its purist aesthetics.

Photos: Schiffbau Immobilien AG and Daniel Ammann, Herisau

Building board

Schiffbau Immobilien AG

arc Architekten AG, Zurich

Facade planning:
Fachwerk F+K Engineering AG

Façade designer / façade builder:
Krapf AG, metal and façade construction Engelburg SG

air-lux drop windows with variable dimmable suspended glass of the SageGlass type.

You can find more photos of the property here

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