Tate Modern Extension, London, United Kingdom

In March 2007 the proposed extension of the Tate Modern was given planning approval by Southwark Council. The £215m extension will provide an annex to the south-west of the existing building and is intended to take the form of a giant and fragmented glass pyramid, or ziggurat.

The extension was designed by Herzog and De Meuron who were responsible for the original Tate Modern, which was based on the original structure of the Bankside Power Station.

Jacques Herzog said about the pyramid design: "It can be interpreted in two ways: as the erosion of a pyramid and, in contrast, as a pyramid in the process of emerging."

The tower will climb up above the brick facade of the existing Tate Modern, changing the skyline of Southwark as seen from St Paul's and the Millennium Bridge that links the Tate to the City of London.

The new tower will be branded as 'Tate Modern 2'; the 11-storey extension will be 76m (250ft) high and will expand the gallery's space by 60% creating 23,400m of new space.

It will cater for the huge increase in visitor numbers, which is currently five million a year, double the amount predicted when the gallery opened in 2000 (25 million visitors since it opened, yet it was designed for 1.8 million visitors a year). Tate Modern is widely recognised as the most popular museum of modern art in the world.

AWARDS AND TIMESCALE

Herzog & de Meuron received the Royal Institute of British Architects' gold medal in February 2007 for work including their redevelopment of the original Tate Modern, adapted from the former Bankside Power Station. Herzog & de Meuron were selected from an international shortlist to further develop the building in January 2005.

Work is expected to start on construction in 2008 on part of the site once occupied by the oil storage tanks of the former power station and the extension will be completed by 2012.

TATE MODERN EXPANSION FACILITIES

The new tower will offer ten new galleries, six cafes and bars, two shops, a range of teaching rooms and a chance for the Tate to show more fine art. There will be new kinds of galleries to house works from the Tate's growing collection, space to show new areas of contemporary visual culture and new galleries for major exhibitions as well as a new performance venue.

The extension will also house new education areas and special areas for Tate members and families. There will also be two new public squares on the south and west of the building for public use.

A spokesperson for Tate said: "A spectacular new building will be created on the south side of the existing gallery to provide more space for modern and contemporary art, and enable Tate to enrich its programme by exploring new areas of contemporary visual culture. Facilities for young people will be central to the new development and learning and visitor engagement will be at its heart."

SPACE UTILISATION

What is not realised is that a large part of the existing Tate Modern building is currently disused. The Switch House, located to the south of the Turbine Hall, still houses an electricity substation that continues to serve a large area of the city and South London.

EDF Energy which owns and operates the electricity substation located in Switch House, need to modernise the equipment there and this has provided an opportunity to move the plant into a smaller area of the building thus freeing up space for Tate Modern expansion to the south. A new building can therefore be developed adjoining the existing building on the footprint of the power station's former oil tanks.

The London Development Agency (LDA) has agreed funding of £7m to meet the total projected costs of the relocation.

TATE MODERN MASTER PLAN

The master plan for the Tate Modern covers the whole site and proposes a series of new public spaces and routes on all sides of the former power station, within which two new buildings will be set.

The first building, which will be located on the site of the disused underground oil tanks, is for the Tate's extension. The potential for a second new building (7,000m²) is also identified in front of the east end of Switch House. This would permit another cultural organisation to move to Bankside. A further planning application would be made for this in the future.

New pedestrian routes will create a new north-south route or 'street' through the building, linking the city to Elephant and Castle (open for at least 12 hours a day). There will also be improved public spaces for visitors to enjoy the Bankside environment.

Over 1,350 new trees will be planted and new seating provided. A new landscaped park surrounding the building, the Bankside Urban Park, is a major project initiated by Tate and Southwark Council and being led by the business improvement district, Better Bankside. This will connect new landscaped areas around the gallery to open spaces across Southwark extending towards the Elephant and Castle.

TATE EXTENSION DESIGN

Level one will contain ticketing, orientation and the cloakroom area. There will be two performance spaces in the disused oil tanks – one is a flexible rectangular box to show a wide range of performance art, installations, broadcasts, concerts and new media.

The second will draw upon the unique qualities of the oil tanks and doubles up as a foyer area. The art space has been created out of the foundations of the existing Switch House. On level two, visitors will approach the newly created south entrance through Tate Square, past the Tate Shop and Tate Café. There will be a meeting room, and a new art space for themed shows from the Tate collection.

Level three will contain a temporary exhibition space to accommodate large exhibitions. There will also be an adjacent shop, staff offices and staff meeting place. Level four will accommodate four new galleries for the Tate collection. Flexible floor heights will adapt to suit works of differing scales.

On level five a bridge will connect the original and new buildings. There will be galleries and workspaces to try out new ideas and exhibit work from community programmes.

The level six Tower Gallery will be used for cutting-edge contemporary art, with a particular focus on innovation.

The level seven 'Tate Lab' is for the exploration of contemporary visual culture. There will be a viewing zone to provide access to the Tate collection of video art, performances and sound archive. There will also be incubation spaces to nurture artists and organisations, sharing knowledge and ideas.

On level eight the Tate Forum will provide the core of a new and ambitious adult learning programme. It will also have a flexible space and a bar. Level nine will accommodate a new member's area and a kitchen. Level ten will house a new restaurant. On level 11, at the top of the building, there will be a public terrace.