Biosphäre Potsdam

The Bornstedter Feld in Potsdam was used as a military ground for more than a century. Redeveloped, it hosted the 2001 Bundesgartenschau (BUGA), Germany's federal garden show. In May 1999 the Berlin practice Barkow Leibinger won the competition for the show's flower hall, built on the southern edge of the site and completed in 2001. The overall Bornstedter Feld development received the German Urban Design Prize (Deutscher Städtebaupreis) in 2002.

After the BUGA the hall was converted, with the practice Dederichs Reinecke & Partner, into an indoor nature attraction, the Biosphäre, which opened on 13 September 2002. More than a hundred trees were planted and a humidification system installed to recreate the atmosphere of a rainforest. The operator at the time, a cinema company with an edutainment focus, expected 320,000 paying visitors a year. The building had cost 29 million euros, of which 21.5 million came from public funding tied to an obligation to run it as a tourist facility until 2016.

A butterfly house opened in May 2009. In July 2016 the city planned to close the Biosphäre at the end of November 2017 and turn it into a multipurpose hall or a private school, but it dropped the plan in April 2017 and sought an operator for twenty years, with an annual subsidy of 1.9 million euros, reduced to 1.6 million in 2022. Run by the municipal company ProPotsdam, the hall by then needed substantial renovation after twenty years of operation.

The hall measures 201 by 72.10 metres, with a roof of about 9,000 m². Barkow Leibinger made use of the relief left by the military earthworks: the hall sinks into the landscape and is defined by new berms, treated as sculptures and faced with exposed concrete, oak logs, turf or slate panels, interrupted by glazed facades. Inside, further berms shape an uneven terrain.

The flat roof rests on 35 precast concrete beams weighing 50 tonnes each, which span 35 metres between the berms and continue as cantilevers; it floats about 5 metres above their crests. It is pierced by glazed sheds of 5 × 8 metres, whose faces are inclined at 15° so that condensation does not drip onto the plants, and covered with coloured pebbles (Verde Alpi, red porphyry, black basalt) that protect the membrane. Ventilation is mainly natural, supplemented by vents that release summer heat, high-pressure misting fed by rainwater cisterns and, in winter, an air recirculation system.

The Biosphäre's rainforest holds about 20,000 plants belonging to some 350 species: orchids and other epiphytes, bromeliads, banana plants, cacao trees, a palm grove, a mangrove swamp, tropical crop plants and trees up to 14 metres tall. A waterfall and two lakes punctuate the route.

Around a hundred animal species live here, including iguanas, snakes, spiders, frogs, mantises, chameleons, turtles, whistling ducks, ant colonies and free-roaming geckos. The butterfly house, opened in 2009, shows about thirty species, and the Aquasphäre presents an underwater world of corals.

The Biosphäre stands in Potsdam's Volkspark, on Georg-Hermann-Allee, on the former BUGA site. Paths wind through the rainforest, past the waterfall, the lakes and the mangrove, to the butterfly house and the Aquasphäre; being fully enclosed, the hall can be visited in any weather.

The programme includes exhibitions, concerts and family activities. The hall called the Orangerie hosts events, and a restaurant looks out over the forest (Urwaldblick). The visit can be extended with a walk in the Volkspark that surrounds the hall.