England

Tate Modern

Herzog & de Meuron

1999

Among the various prestigious projects that marked the passing of the Millennium in London, one of the most successful was the conversion of the Bankside power station.

Client: Schal International Management Ltd
Main contractor: Schal International Management Ltd
Fa├žades: 3 500 m2
Type: Renovation
City: London

The original building, whose remarkable outline has stood out on the Thames since the fifties, was designed by the architect Giles Gilbert Scott, and has been recognised as a model of post-war industrial architecture.

After being closed down in 1981 for economic reasons, the site was acquired by the Tate Gallery, with the intention of re-housing its extensive collection of modern art there.

The architectural risk imposed by the scale of the building, its location in the centre of the city and even the nature of the projected programme itself was the subject of an international architectural contest, from which Herzog and de Meuron from Basel emerged as the winners. The strength of their project lay in its coherent concept, linking a modern style, light and the enhancement of the original building.

The main facades and the imposing central chimney, with their large surfaces elaborately worked in fired brick, have been preserved. The significant contribution lies in the addition of a completely glazed attic construction , running the entire length of the building (180 rn long by 18 rn wide) with a height of two stories (9 m ).

These large, glazed surfaces distribute a gentle natural light into the exhibition halls (translucent windows) and also open up certain spaces by offering splendid views over the city (transparent windows) .

The architectural task of imposing a maximum of transparency without any apparent structure represented the main constraint for the design and the execution of the facades. Very large volumes of glass must cover the 1,350-mm-wide framework with two superimposed heights of 4,065 and 4,710 mm.

The production of glass with the requisite dimensions necessitated an unusual co-ordination between the various sites responsible for the production, tempering, edge polishing and assembly of the special laminations.

The creation of windows with transparent and translucent zones laid within a single insulating glass pane is unheard of. The process consisted of meticulously superimposing transparent and opaque sheets of PVB during the assembly of the laminated glass, while ensuring a perfect joint at mid -height. The special white rendering of the facade is obtained by the choice of a " low iron" glass combined with an opaque PVB.

The structural constraints require that the facade cover a height of 9 m without being fixed to the intermediate concrete slab, which is too weak. A special RHS 120150 1 8-10 profile had to be created, therefore, as the required thickness was not available in standard profiles. Steel RHS 120 1 50 1 3.5 crossbeams complete the supporting structure. For the finishing, aluminium caps made to size clipped over the whole.

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