Biosfera, Renzo Piano's Glass Bubble (La Bolla)

The Biosfera grew out of the long recovery of Genoa's Porto Antico, the old harbour, which Renzo Piano Building Workshop carried out for the City of Genoa and Porto Antico SpA between 1985 and 2001: design from 1985 to 1988, construction from 1988 to 2001. The glass sphere was added in 2001, the year the works came to an end, on the occasion of the G8 summit hosted by the city. According to the Renzo Piano Foundation, it was meant to show a remarkable collection of ferns in a suitable habitat.

The project was financed by the company Ignazio Messina & C. Its chief executive, Paolo Messina, officially inaugurated the sphere on 19 January 2002 together with the then mayor of Genoa, Giuseppe Pericu. Technical problems forced its closure as early as February 2003, and it reopened on 1 October that year.

Also known as the Bolla di vetro (glass bubble) or the Bolla di Renzo Piano, it is now attached to the neighbouring Aquarium of Genoa and forms part of its visitor route, within the complex the operator presents as AcquarioVillage.

Designed by Renzo Piano, the Biosfera is a sphere of glass and steel 20 metres in diameter, weighing about 60 tonnes in all. It hangs over the water of the harbour at Ponte Spinola, right beside the Aquarium, and encloses some 200 square metres of exhibition space. The Renzo Piano Foundation credits Ove Arup & Partners with the services engineering and environmental studies.

Inside, the temperature ranges from 14 °C in winter to 30 °C in summer, with humidity held at a constant 60 per cent. Two systems share the work. In winter, an artificial system relies on thermal machines placed beneath the sphere, where heat pumps draw warmth from the seawater before it is distributed through radiators. In summer, a natural system of movable sails follows the course of the sun to regulate the radiation entering through the glass. Computerised control of this equipment sustains the microclimate of a humid tropical forest inside a fully glazed volume standing in the open harbour basin.

More than 150 animal and plant species recreate a fragment of tropical rainforest. Tree ferns up to seven metres tall form the backbone of the planting, which also includes palms, banana plants, coffee, cocoa, cinnamon, vanilla and what the official site calls the chewing-gum tree. The site also highlights Passiflora phoenicea, a passionflower that grows two false butterfly eggs on each leaf stalk as a means of defence.

The most conspicuous resident is the scarlet ibis (Eudocimus ruber), with its intense red plumage, a bird of the mangroves, tidal zones and estuaries of north-eastern South America. Sources also mention Moluccan cockatoos, turtles, fish including African cichlids, insects, butterflies and iguanas, so that the sphere works as a small living ecosystem rather than a plant collection alone.

The sphere stands in the Porto Antico at Ponte Spinola, immediately next to the Aquarium of Genoa, and is visited as part of the AcquarioVillage offer rather than as a separate garden. Its modest size makes for a short visit, but it is worth lingering to follow the birds through the fern canopy and to look back at the harbour through the curved glass. Winter visits sharpen the contrast between the humid tropical air inside and the sea just outside. The visit fits naturally into a day around the Porto Antico, whose quays Renzo Piano redesigned between 1985 and 2001.