Air-Lux at Winterthur and Bürgenstock

Project: Lakeview Residence Villas at Bürgenstock Resort, 2017​
Location: Obbürgen, Switzerland
Architect: Stücheli Architekten

Project: Winterthur Residential Tower, 2017
Location: Winterthur, Switzerland
Architect: Wild Bär Heule Architekten in collaboration with Christa Lippuner

Manufacturer: Krapf AG
Product: Air-Lux, frameless sliding sash with air-assisted sealing system

Stücheli Architekten's Lakeside Residence Villas at Bürgenstock Resort take advantage of their prime location along a ridge above Lake Lucerne by building vertically. A series of five-story buildings separated by narrow gaps follow the ridge and contain villas ranging in size from 538 to 814 square meters. The site plan (visible in a Praxis feature at German-Architects) ensures that the villas form a courtyard with the other resort buildings and have unobstructed views of the lake. The generously sized villas also have generous 3-meter-tall living spaces with floor-to-ceiling windows.

The large windows frame dramatic views from the raw spaces (to be finished by the residents) and slide open to allow access to balconies partially shielded from the elements by limestone walls. The site's strong winds and driving rain pointed to Air-Lux's robust, air-assisted sealing system. In it, a ring seal is inflated by the push of a button; when the window is pressed against the sliding profile, the gap between the window and the sliding element is completely closed. Conversely, when opening the window, the seal is deflated and retracts via a pressure-sensing pulse. (See detail and video at bottom for visual explanation of Air-Lux's sealing system.)

In Winterthur, northeast of Zurich, Wild Bär Heule Architekten did not have stunning lake views to contend with. Quite the opposite, the four-story Winterthur Residential Tower sits in the middle of a block dense with houses and apartment buildings. Although hemmed in on all sides and limited to a 400-square-meter footprint, the four full-floor residences have completely glazed exterior walls (minus the concrete stair tower). The architects were inspired by Mies van der Rohe's Farnsworth House in Illinois; just as Ms. Farnsworth needed curtains for protection from the sun and prying eyes, the residences in Winterthur restrict the same through exterior roller shades and interior curtains.

The Air-Lux installation consists of 32 air-tight sliding windows supported by steal beams. Without terraces, as at Bürgenstock Resort, Inox wire mesh covers the openings to protect the residents from falls but also to keep the curtains from blowing outside. Suitably, the mesh is dense near the floor but more open toward the top, so as to not distract from views of sky and clouds. Still, the Air-Lux installation here is more about letting the outdoors inside rather than accentuating views ― of which there are none.