The City of Augsburg in Germany is the oldest city in Bavaria and second-oldest in Germany. It is well known for its buildings, churches and idyllic ramparts with towers from the Renaissance era. Augsburg was founded in 15 BCE by the Romans and was named after the Roman emperor Augustus. Therefore, the old part of the city has numerous museums to help visitors discover 17 centuries of art and history. One of them is the St. Afra Diocesan Museum.
Cover image: The ISOshade® façade provides a welcoming and pleasant experience. © BECKER LACOUR
The St. Afra Diocesan Museum is located in the city centre and is home to a modern, permanent exhibition and temporary special exhibitions. The building is a marvel in itself, harmoniously combining a modern complex with mid-twentieth-century architecture and a Romanesque chapter house as well as the late Gothic cloister and Chapel of Saint Ulrich of Augsburg. On display in the museum are Roman relics, the famous Ottonian bronze portal of Augsburg Cathedral, precious medieval textiles, the extraordinary funerary arms of Holy Roman Emperor Charles V, Gothic and Baroque church treasures from Augsburg and the surrounding region plus modern-day works of art.
High energy costs
Recently, the museum underwent a major renovation, primarily to reduce very high energy costs. The museum was suffering from severe temperature fluctuations inside the building caused by high solar gains via the east façade and the glass roof. To keep the interior climate as constant as possible and protect the exhibits, humidification-dehumidification units were installed, which have a high energy consumption.
The solution was obvious: Install insulating glazing to replace the existing east façade with its mullions and transoms. In addition, a variable sunshading system was required to protect the museum’s exhibits from sunlight, but at the same time allow enough light into the interior during other times – especially to present and protect the heart of the exhibition adequately: the famous bronze portal. The old bronze door of Augsburg Cathedral is one of 12 important Romanesque bronze portals in Europe and is one of the best examples of medieval foundry art north of the Alps.
Refurbishment of the façade
Local architectural practice Schrammel was appointed for the renovation work, including the refurbishment of the glass façade. The design brief proposed a transparent glass façade that combines solar, thermal and sound insulation. A double-skin façade seemed a good solution as this technology is one of the most advanced forms for enabling maximum use of solar energy by allowing heat gains and preventing thermal energy losses in buildings. However, a conventional double-skin façade appeared much too expensive and oversized for the façade to the museum’s lobby. So façade specialist seele was brought in and promptly suggested ISOshade®.
Reduced to the essentials
Façade specialist seele is famous for its profound research activities and its work on solutions to reduce material usage and energy consumption. A focus on environmental, architectural and social qualities is needed in addition to the functional properties of a façade design. Ventilated double-skin façades emit more greenhouse gas equivalents than a double-glazed curtain wall, taken over its lifetime. Therefore, ISOshade® is designed much more consciously with regard to reducing the consumption of resources, and the options for prolonging the lifetime of the façade are rigorously considered. Each unit is designed to be overhauled several times and thus extend the lifetime of the energy-consuming parts.
Conceived like insulating glass, ISOshade® fulfils the requirements of a double-skin façade with sunshading. ISOshade® is a compact insulating glass unit consisting of triple glazing and a sunshading system integrated in one cavity. The built-in sunshade can be in the form of a louvre or roller blind. An outer glass pane protects the blind against dirt, wind and weather, at the same time eliminates wind noise and cleaning costs. The blinds protect, in fact shield, against excessive solar gains depending on time of year and climate zone.
The seele solution for the museum offers a decisive advantage: A specially developed pressure equalisation system regulates climate loads and pressure differences due to temperature fluctuations and minimises the moisture in the cavity. Desiccants fitted in the frame prevent condensation between the panes. That means ISOshade® reduces the complexity of façades with integral sunblinds and can be planned and installed just like normal insulating glass units.
The advantages convinced the client, the Diocese of Augsburg. This façade type was chosen as its double-skin design provides the perfect solution for regulating the internal climate through the façade. “Inside the museum, we face different challenges. We want to provide visitors with a pleasant interior with ample daylight, but at the same time protect sensitive exhibits against sunlight. An insulated glass façade was the right solution for us. The integral louvre blind can be adjusted regardless of the weather conditions. Even during a snowstorm or high winds, it is possible to adjust the angle of the slats, and they make no annoying noise,” says Museum Director Melanie Thierbach.
Big formats for a unique design
seele built a mock-up of the proposed sunblind so that various settings could be presented, a lighting atmosphere generated or different visitor perspectives simulated. This convinced the architect and the client, and so seele was commissioned with the design and fabrication of the ISOshade® elements. An oversize format (2.2 x 6.7 m) was chosen so that the elements could extend uninterrupted from floor to roof, thus permitting unobstructed views of the area in front of the museum. The museum’s elements have an identical glass make-up: triple glazing on the inside and laminated safety glass on the outside to ensure intruder resistance. The integral louvre blinds (80 mm flat slats, RAL 9006) are bespoke, oversize products supplied by Warema.
This museum façade demonstrates that a complex façade form does not necessarily have to be expensive. Elements cleverly designed and combined by seele follow a different line, achieving more at lower cost. Particularly worth mentioning is another example of serial production by seele: the hyperbolic façade surfaces of the European Central Bank in Frankfurt. Despite the individual symmetry of the 6,081 façade elements, seele developed a system that enabled serial production. It’s the same with ISOshade®: seele designs all elements – and assembles them in cleanroom conditions – to suit the prevailing conditions (climate, location) and the specification. The glass itself (heat-strengthened, laminated safety glass), acoustic interlayer and solar-control coatings are chosen to match the performance brief.
Easy installation method
In the case of the museum, seele was involved in the planning, design and production process, but just served as the “supplier”. Installation was carried out by a local metalwork contractor. Although the elements were somewhat larger, lifting the oversized panels with a suction-cup system was no problem. The city-centre location and cramped site conditions in a narrow alley called for a perfectly coordinated logistics and erection concept. Transport frames were used to transport the units safely. On site, the ISOshade® elements had to be manoeuvred with millimetre accuracy, as the space available was very limited.
Within a day, the oversized, but compact, ISOshade® elements were installed with maximum precision. The compact design is particularly beneficial when it comes to the typical site circumstances often faced in big cities such as London, New York, Berlin or Hong Kong. In such cities especially, where space is tight, quick and easy installation with prefabricated and preassembled units enables fast-track procedures.
Structural glazing, silence and shade
The special feature of the design is that the façade essentially consists of only a few parts. Each element is clamped to structural members top and bottom. The vertical joints between the three elements were sealed after installation. After connecting the integral sunblinds to the building services, the exhibition space could be furnished once again.
Today, an attractive, homogeneous entrance façade welcomes visitors. The built-in sunblinds regulate the amount of incoming heat and light regardless of wind and weather. Excess solar energy can therefore be screened off right at the window or directed into the furthest corners of the room for maximum interior comfort without glare, depending on the time of year. The amount of incoming light can be controlled individually at any time by adjustable slats to achieve an optimum energy transmittance of 8 to 50%. The new façade ensures an ideal climate for the light-sensitive relics and exhibits.
Visitors to the museum can now also enjoy a pleasant interior climate. The double-skin design comprising low e glass and external pane achieves Ug values as low as 0.5 W/(m2K) and outstanding sound reduction index values of 44–52 dB, which results in an agreeable, quiet interior. Additional comfort is assured by the adjustable sunblind. In summer the heat stays outside, but in winter the solar gains can be exploited. With its new façade, the museum now benefits from reduced costs for heating and cooling the building’s interior. A removable panel allows access to the cavity for maintenance, which prolongs the lifetime of the museum’s façade.
For continuous monitoring purposes and early detection of faults and damage in order to carry out targeted maintenance work, the façade elements are equipped with sensors that measure important characteristic values in the cavity. Information on the condition of the ISOshade® component can be retrieved using the built-in sensors, changes detected via time series analyses and the sunshade operated via the digital model. This kind of predictive maintenance was part of the refurbishment project and will also extend the lifetime of the museum’s façade.
Serial but bespoke
Although the façade for the Diocesan Museum is not a conventional seele façade, being more or less a product of serial production, it still captivates through its bespoke design, which combines aesthetics and functional criteria. No horizontal members interrupt the glass, which helps to create lightness and transparency despite the dimensions. Nevertheless, this modern façade fits perfectly into the existing wall openings and does not steal the show from the impressive old building of the St. Afra Diocesan Museum. Following the renovation, the museum and façade are worth a visit any time of the year.
About ISOshade® -the façade with the built-in sunblind
ISOshade® consists of triple glazing plus a sunblind fitted in a cavity. The slim ISOshade® elements (min. 130mm thick) are ideal for densely built-up areas and at the same time enable smaller façades to benefit from all the advantages, too. An ISOshade® façade is tailored to the specific conditions of a project. seele provides a full range of services comprising design, fabrication, transport and erection.
- Protected sunshading elements
- Prefabricated units
- Plug & Play façade
- Excellent sound insulation
- Lower heating and cooling costs
- Energy efficiency
- Zero maintenance
This article was originally published in IGS Magazine’s Autumn 2021 Issue – Glass Retrospective: Read the full Magazine here for more thought-leadership from those spearheading the industry
Michael Seele is the Sales Director at façades specialist seele, one of the world’s top companies specialising in the design and construction of façades and complex building envelopes made from glass, steel, aluminium, membranes and other high-tech materials. His many years of experience in the field of façade engineering already includes numerous high-profile projects such as King’s Cross station in London, ICONSIAM in Bangkok and the K11 Musea Tube Façade in Hong Kong. In his role as Sales Director, he develops sales activities all around the globe. Michael Seele is also responsible for pushing the development of seele’s ISOshade® and GSP® products throughout the whole group of companies.