Amazonienhaus Wilhelma, Stuttgart, DE
Sunny times for the Swabian primeval forest.
The flora and fauna of the Zoological and Botanical Garden in Stuttgart, better known as Wilhelma, attracts up to two million visitors every year. With almost 9,000 animals and almost 1,100 species on an area of 30 hectares, Wilhelma is the second most species-rich zoo in Germany after the Berlin Zoological Garden. The inner-city park and gardens, which emerged from a historic palace complex, were opened as early as 1853. The special flair of Stuttgart’s Wilhelma is made possible by the mixture of modern animal enclosures and the Moorish-style buildings, which were built in the 19th century according to the wishes of the then King of Württemberg based on the model of the Spanish Alhambra.
Project data
Architect
Auer + Weber + Assoziierte, Stuttgart
Client
Wilhelma, Stuttgart
Planning and installation
Roschmann Konstruktionen aus Stahl und Glas GmbH, Gersthofen
Products
usedGEWE-composite®
Glass supplier
Schollglas Technik Sachsen GmbH, Nossen
Modern architecture for flora and fauna away from civilization
One of the biggest attractions is the Amazon House, which was inaugurated in 2000. In its single-nave, 66-metre-long, 18-metre-wide and 14-metre-high hall, the greenhouse with 350 different plant species shows a section of the Amazon rainforest. In order to depict the conditions of a primeval forest as naturally as possible, visitors are not guided through the building on fixed paths as usual, but on a narrow forest path strewn with bark mulch along two larger bodies of water with waterfalls through the flora and fauna of Amazonia. More than 20 species of birds fly freely in the lush South American vegetation.
Additional light sources to support sunlight
All year round, temperatures of 24 to 28°C and 80 percent humidity ensure a plant-friendly climate in the Amazon House. So far, 48 luminaires support the sunlight entering through the glass roof and walls. However, the incident daylight was increasingly less sufficient to guarantee plant growth, and the glazing installed during construction no longer allowed sufficient sunlight to pass through.
Above all, the increasing lack of ultraviolet light components proved to be problematic. The state of Baden-Württemberg and Wilhelma therefore decided to completely replace the old glazing. Although a simple insulating glass pane and a light thermal insulation layer can achieve very good results in terms of permeability to UV radiation, overhead glazing made of laminated safety glass (LSG) is necessary in the Amazon House. Since LSG is usually provided with a UV-absorbing PVB film that transmits less than 1 percent of the radiation necessary for the plants, this glazing variant was ruled out. Very good results were already achieved with the laminated safety glass GEWE-composite® during the renovation of the Frankfurt Palmengarten in 2007. Based on this reference, the Stuttgart-based company also opted for glazing from SCHOLLGLAS.
Main product GEWE-composite®
GEWE-composite® is a laminated glass consisting of two or more thin mono glasses from a thickness of 1.9 millimetres, which are bonded to a transparent plastic core to prevent shear-stiffness. GEWE-composite® combines the properties of glass with those of transparent polymers – in particular a high fracture and residual load-bearing capacity with a simultaneous possible weight saving of around 30 percent.
In the Amazonienhaus, insulating glass consisting of an 8 mm or 10 mm GEWE-dur-H® white glass pane with Low E coating, a 16 mm pane between the panes with argon gas filling and a 10 mm thick GEWE composite® pane made of white glass panes were made for the façade and overhead glazing in the roof area. The building authority requirements for Wilhelma’s Amazonienhaus, which were placed on the product GEWE-composite® in the course of approval in individual cases, easily fulfilled the tests carried out.
The lens composite achieves a UV transmittance of approx. 37 percent with a g-value of approx. 0.54. The argon filling in the space between the panes and the thermal insulation coating achieve a heat transfer coefficient of 1.1 W/m²K and thus excellent insulation values. The light transmittance is about 81 percent.
Special requirements for the protection of substructures
In order to protect the edge bond of the glazing, care was taken during the installation of the glazing to ensure that the indoor air with a humidity of approx. 60 – 80 percent does not enter the rebate space of the construction. For this purpose, the glaziers from the Roschmann company in Gersthofen installed special support profiles and glued them all around with silicone. On the outer sealing level, several ventilation openings ensure that water vapour is dissipated to the outside.
For the gardeners at Wilhelma, the new glazing means more work in the future. While their concern has so far been more about the preservation of the damaged plants in the Amazon House, they will soon have to take the secateurs in their hands again to get the lush jungle vegetation under control.
