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Safety Glass

Bolzano’s new art museum features a layered facade with minimally supported SentryGlas®

Front and rear facades made of laminated safety glass contribute significantly to the transparent architecture of Bolzano’s Museion, conceived and planned by KSV Krüger Schuberth Vandreike Planung und Kommunikation GmbH (Berlin).

Photos ©KSV Krüger Schuberth Vandreike | Photography: Ludwig Thalheimer / lupe

Deeply recessed concave entranceway and facade draws visitors toward an expanding view of the Museion’s inner activities and displays. The facade also also serves as a night-time projection screen.
The facade glass panels are positively held at each corner, using fixtures developed by Vega System.

Two opposing, funnel-shaped glass facades emphasize the transparent, invitingly-widening architecture of the "Museion", Bolzano’s new museum of modern and contemporary art. Opened in the summer of 2008, it was extensively conceived and planned by the Berlin-based architects KSV Krüger Schuberth Vandreike. For the production of the exterior laminated glass panels, used in the building’s double glazing, the northern Italian facade specialist Vega Systems, in cooperation with the architects and the engineering office Studio Cattivelli, chose strong and stiff DuPont™ SentryGlas® interlayers, well-known for their ability to create highly resilient laminates and their post breakage performance. Such properties have enabled the creation of relatively thin glazing, reaching up to 25 meters high and, in sections, acting as an overhead installation, which is able to meet rigorous safety requirements and requires only small, unobtrusive point fixtures to securely hold the panels in place – even at high wind forces. In such a way, the building is able to transmit a sense of inviting lightness, assimilating and perpetuating the white, almost monochrome design of its interior floors.

Strength, Safety and Inviting Lightness

The "Museion" views itself not just as a receptacle for artwork, but as an interdisciplinarily aligned international art laboratory. “The Museion is a communicative museum, combining the flexibility and openness of a workshop with the qualities of a classic gallery,” explains Bertram Vandreike of KSV. “A metal envelope encases the length of the stretched cube. In contrast the two front ends have been created as large, transparent windows to the city and surrounding landscape. Through the glazed entrance facade, the interior of the museum, with its exhibition floors, library, education center, shop and information point are visible to the outside world.”

Thin Laminates with Low Deflection

Standard laminated safety glass, made with polyvinyl butyral (PVB) interlayers, would have needed to be a lot thicker in order to provide long-term resistance to the specified wind strengths. Due to the large dimensions of the individual panels, with widths of up to 1.75 m and heights of up to 2.4 m, a comparatively expensive supporting framework with very large fixtures would have been required to withstand the weight of the panes and the additional wind forces.

SentryGlas® interlayers are considerably stronger and approximately 100 times stiffer than PVB. As a consequence, there is almost perfect load transmission between the laminated glass sheets – even at higher temperatures – which actually behave similarly to monolithic glass. This is a byword for the excellent flexural behavior of the laminate under load, even under direct sunlight during mid-summer. Accordingly, laminates with SentryGlas® demonstrate only half of the deflection rate of comparable PVB laminates when the same load is applied, and is thereby similar in its behavior to monolithic sheets of the same thickness. Further benefits are its high, crystal-clear transparency, its virtually universal resistance to yellowing and excellent edge stability.

Extensive Testing

The structural designer Fausto Cattivelli comments: "The immense resilience of laminated safety glass made with SentryGlas® is still greatly unknown. Public authorities and architects, coming across it for the first time, are always astounded by its performance. It was the same case when we, in partnership with Vega Systems, proposed the material for the facades of the 'Museion', including the overhead sections. Indeed, we only received regulatory permission for the material to be used following extensive testing, some of which was carried out independently, which included the glass panels being loaded with bags of sand until they actually broke. The loads achieved were to the ultimate satisfaction of all parties, as well as the fact that, post breakage, the laminated safety glass with SentryGlas® was still able to provide long term support to high loads. The broken panels show very low deformation, even after 24 hours at 50°C, and the glass fragments remain securely adhered to the interlayer."

Ultimately the team decided for a laminate consisting of a 12-mm thick sheet of tempered glass, a 1.52-mm SentryGlas® interlayer and a 12-mm heat strengthened glass sheet in the lower, perpendicular sections. For the upper, overhanging sections, a laminate consisting of two 12-mm (0.5 inches) heat strengthened glass sheets with a 1.52 mm (60 mil) SentryGlas® interlayer was used. Production of the laminated safety glass panels was contracted to the experienced Italian laminator Vetrodomus S.p.A. of Brescia.

Double Glazed Envelope Controls Air and Light

The double glazing which forms the transparent and spatially-unmistakable entry and shop window to the "Museion", also performs essential technical functions. The space between the glazing is used as an active climatic envelope. Circulating within it is air on its way between the roof and the mechanical equipment room in the basement, facilitating the efficient utilization of energy used for temperature control. In addition, maneuverable, mat glass slats, integrated in the same space, are used to modulate the ingression of daylight to the building, enabling the best possible presentation of the exhibits in line with their character. Then, after dark, the slats – at the press of a button – transform the glass facades into giant projection surfaces for projectors installed within the museum.