Orang-Utan-Haus (Orangutan Dome), Hagenbeck Zoo

The Orang-Utan-Haus replaced a great ape house built in the 1960s. According to the architectural office that designed the new building, the old facility no longer met the demands of species-appropriate husbandry or the expectations of a better-informed public, so Tierpark Hagenbeck, which opened in Stellingen on 7 May 1907, decided to build a groundbreaking installation for orangutans.

The sources give two versions of the timeline. The zoo's website speaks of more than ten years of planning and one year of construction, while the ZooLex entry, written by the zoo, dates the start of design to December 2001 and the start of construction to September 2003. The building opened on 27 May 2004, as both ZooLex and BauNetz confirm, and the group of the time, eleven orangutans according to the zoo, explored its 5,280 m³ for the first time.

ZooLex gives a cost of EUR 4.6 million including design fees; the City of Hamburg supported construction, while the zoo bears the maintenance. The zoo's site also cites city support of EUR 4.6 million. The architecture is by the Hamburg office PSP (PSP Architekten Ingenieure in ZooLex and on the firm's own site, PSP Pysall, Stahrenberg und Partner in BauNetz). The dome was supplied by Skyspan (Europe) GmbH, the structure calculated by Wetzel & von Seht, the technical engineering handled by LMT Ingenieur und Planungs GmbH and the landscape by Peter Plomin. In 2004 the Architekten- und Ingenieurverein Hamburg named the building its "Bauwerk des Jahres".

The building has two parts, a circular base and a dome. The base, whose reinforced-concrete outer wall carries the loads of the dome, houses the technical rooms, the food-preparation kitchen, the staff areas and the animal stalls. The architects explain that Hamburg's climate did not justify a separate outdoor and indoor enclosure, so the project was conceived as a covered outdoor enclosure.

The hemispherical dome measures 32 m in diameter and 16 m in height. It is a steel ribbed net filled with multi-layer, air-filled ETFE cushions rather than glass: the architects stress that this fluoropolymer lets UV light through, which allows plants to grow, and shading comes from a silver dot pattern printed on the foil. ZooLex adds good thermal insulation, low weight and a self-cleaning effect. Half of the dome is movable, and opening or closing it by motor takes seven minutes. In summer, opening it regulates the temperature; in winter the dome is closed and an automatic heating system keeps temperatures even.

The volume accessible to the animals reaches 5,280 m³. Ditches, water areas, rock-look concrete and glass panes replace fences, and the height differences in rock concrete and earth fill carry stairs, a tree house and a suspension bridge.

The enclosure holds Sumatran orangutans, which give the building its name, and small-clawed otters (Zwergotter in German Wikipedia) that occupy the water moat beside the visitor area. The ZooLex entry (December 2005) gave 1 male and 12 female orangutans with offspring, and a pair of otters. The zoo's home page lists a commented orangutan feeding among its scheduled presentations.

The planting aimed to evoke the rainforest of Sumatra and to enrich the animals' surroundings. The plants are out of reach of both animals and visitors, and the zoo expected the dome to fill gradually with dense foliage. The list published by ZooLex has 26 entries. It includes palms (Phoenix roebelinii, Washingtonia robusta), Cycas revoluta, tree ferns including Cyathea australis, and Monstera deliciosa, Medinilla magnifica, Ficus lyrata, Bambusa vulgaris, Pandanus veitchii and Passiflora quadrangularis. Trees of temperate climates also appear: Carpinus betulus, Catalpa bignonioides and Ailanthus altissima.

The Orang-Utan-Haus is visited with admission to Tierpark Hagenbeck. According to ZooLex, visitors approach it over a suspension bridge or a paved path, then pass a terrace and an Indonesian-style entrance building. Inside, only moats, water and artificial rocks separate people from the animals; a restaurant and a raised platform give views at canopy height, and a staircase leads to a second terrace overlooking the enclosure when the dome is open. The interior is wheelchair accessible.

The dome is open in warm weather and closed and heated in winter, so the atmosphere changes with the season. The zoo schedules a commented orangutan feeding (times on its home page). In the same park, the Tropen-Aquarium (opened 2007, over 8,000 m²) is a separate building that rounds off a visit.