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Transparency for the 'New Reichstag' in Berlin

In the evening, the illuminated Reichstag dome is transformed into a beacon that can be seen from all over Berlin.

The most impressive government building to be officially opened in Europe this year is undoubtedly the Reichstag in Berlin, Germany's historic parliament building originally built in 1889 but substantially damaged by fire during the second World War.

Foster and Partners won an international design competition for the re-design of the Reichstag, back in 1993. The firm's Berlin office told LGN: "Our brief was to accommodate a new debating chamber for the German parliament within the existing building, as well as new, administrative offices and other modern office spaces."

The firm's guiding idea was to "get the public into the building" – a concept that the client enthusiastically endorsed. Therefore the architects designed the 'New Reichstag' with maximum transparency – both physically and metaphorically. The challenge was to combine this transparency with maximum security and safety for parliamentarians and visitors alike.

Creating a building that is environmentally intelligent was another driving idea. The original dome, demolished in 1954, has been re-interpreted in a modern way as a solar collector and re-instated above the debating chamber. This allows the daylight flooding through the glass dome to transmit natural daylight all the way down into the chamber.

Through the widespread use of laminated glass, Foster and Partners was able to combine security and safety requirements with a high degree of natural daylighting, transparency and environmental efficiency in the Reichstag building.

Viewing platform

The architects' remarkable design allows the public to enter the building and walk up inside the dome on a double-helix ramp to a spectacular viewing platform atop the dome. The ramp spirals from the roof terrace into the massive, laminated glass dome 38 meters in diameter and rising to a height of 24 meters from the roof terrace level. The ramp is of steel and acts as a structural support for the dome: the balustrades are of laminated glass (16mm in thickness) so as not to obstruct the view down – or out through the dome.

As well as appreciating the wonderful views across Berlin from the dome, visitors can look down into space within, directly into the chamber through a 'false skylight', 15 meters in diameter. The skylight is made of 50mm laminated glass and has passed extensive German testing for safety and fireproofing.

Daylighting inside the Reichstag is enhanced by a central light cone of reflective laminated glass mirrors.

Central 'light cone'

The optimal daylighting within the Reichstag chamber is enhanced through the use of a central 'light cone' made of highly reflective, laminated glass mirrors. To enable the highest level of light transmission through the dome and onto the mirrors, laminated glass 20mm thick was used, made from two sheets of 10mm, Opti-white glass with a 0.76mm layer of PVB. This glass contains almost no iron and so transmits a clearer light than standard, greenish glass.

The laminated glass panels of the dome are not curved but flat. The dome is therefore faceted (the panes, specified by computer simulation, range from 5.1m x 1.8m down to 1.8m x 1.8m) so that the light is directed straight onto the corresponding facets of the central conical 'mirror'. All the laminated glass for the Reichstag dome was fabricated by Bischoff of Aachen, Germany.

The inspired Reichstag re-design was celebrated as a milestone of European architecture at its official opening in April and makes an impressive setting for the election of the new German president in September 1999 when Germany's parliament will take up official residence there.