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Tour Eqho, La Défense, Paris, France

Issue 78 April / May 2014 : Commercial : Office Building

Architects: Hubert & Roy Lighting Design: Concepto studio

La Défense is the financial centre of Paris and sits at the western end of the Axe historique, a line of monuments that leads from the Louvre through the Arc de Triomphe to the centrepiece of the area L’Arche de la Defense. Concepto Lighting Design developed a lighting scheme for the refurbishment of the nearby Eqho Tower, ensuring the structure continued to live up to its lusty neighbours.

Every major world city, as the times changed and commerce fully replaced conflict as the arbiter of power on the continent, needed a brash and impressive central business district, full of glass skyscrapers and architecture that spoke of power and wealth. New York never had a problem with this as business has always grown hand in hand with the city.

The transformation of London’s Square Mile was made easier by the destruction wrought by Hitler’s bombs during the Second World War, the city needed to be re-made and most sites were fair game for redevelopment, as long as new structures were respectful towards the iconic talisman of the area, St Paul’s Cathedral.

In Paris the choice of site for a financial centre was some-what tougher, by a minor-miracle the city had survived the war intact and the beautiful Haussmann boulevards were hardly going to give way to the march of commerce. So the city authorities had to look outwards, towards the old city limits and La Défense, an area named after a statue marking the heroic defense of Paris during the Franco-Prussian war.

Starting in the late 1950s the towers of La Défense began to rise out of farmland at the very edge of the city’s 20 arrondesments. The area really began to come into its own during the presidency of François Mitterrand, a man who had set his mind on leaving an architectural legacy on the city to match the sweeping reorganisation of Paris seen during the reigns of Napoleon III and Louis XIV.

Mitterrand didn’t come anywhere close to matching their achievements, but he did leave a series of modern Parisian monuments including the Louvre Pyramid and the Opéra Bastille. One of these ‘Grands Projects’ as they were nicknamed was the Grande Arche de La Défense, a great white structure that sits in the middle of La Défense echoing the Arc de Triomphe. It was built as a monument to humanitarian ideals, rather than to military victories like its brother on the Champs-Elysées and represents perfectly the overall feel of La Défense as a light and airy space, free of the bombast and overt patriotism of central Paris, a secular, relaxed space, with sharp modern architecture created to exude, and to make, money.

In 1988, the middle years of the Mitterrand presidency, the Descartes Tower was built. Later renamed the Eqho Tower, the 130-metre high-rise echoes the architectural style of the Grande Arche de La Défense, a simple, sleek design that, nevertheless, manages to make a grand statement.

The building was fully refurbished in 2011 and this included a complete restructuring of the building’s lobby in order to allow for the entry of natural light and to open the space up visually to the bridge-type structure that supports the tower. A renewal of the building’s façades was also proposed.

French architectural studio, Hubert & Roy and lighting designers Concepto studio were approached to work on a daytime and nocturnal lighting scheme for the lobby.

In addition to wide doorways out into the impressive urban environment that surrounds the structure, the lobby of the Eqho Tower has a large glass roof twelve metres above floor level. It is suffused in natural light, which changes the space as the days and seasons alter.

At certain times of the year, and depending on the path of the sun, sunbeams shine into the lobby beneath the bridge, projecting onto the walls and floor the shadowy silhouetted spans of the metal meshlike structure above.

To breathe life into the space, highlighting the lobby’s size while revealing the sun and the changing seasons, a glass installation, consisting of coloured tinted dichroic glass was integrated directly into the laminated panels in the glass roof and reflective panels made of mirror-polished stainless steel were suspended vertically.

Dichroic glass has the ability to colour rays of light passing through it, changing the colour within a predefined range, in this case, from blue-green to purple, depending on the variations in the angle of incidental sunbeams. Dichroic glass also reflects sunbeams by colouring them differently from the rays being transmitted.

Because of this installation the sun’s rays are projected onto the floor and the white walls of the lobby, generating spots of colour that slowly move and change tone throughout the day. Mirrored panels have also been hung vertically within the space to allow the coloured rays to be deviated and projected onto the inner wall of the north-facing auditorium, an area that never receives any direct sunlight.

The chromatic density of the various panels of coloured glass used in the atrium is increased in the southern portion of the glass roof, in order to reduce the light and heat caused by the sun during the often-hot Paris summer. In the winter during the beginning and the end of the day, the sun strikes the building at an acute angle, so the space is flooded with light from the large vertical clear glass walls. Due to these features the lobby has become a light trap offering occupants and visitors interesting, moving and changing images during the day and throughout the year.

At night the entire lobby is lit by ERCO Beamer projectors equipped with various optics and 150W ceramic metal halide lamps from Thorn, which have been mounted above the glass roof on the exterior of the building, along a metal duckboard that was installed to enable easy maintenance work.

This lighting system makes it possible to use the metallic mesh like a huge stage grid, concealing the lighting fixtures from view. The beams of light shine vertically downwards, into the lobby, lighting the floor of the ground floor, as well as the openings into the basement, the stairs and the walls.

The average illuminance in the lobby is 150 lux, with additional light picking out certain areas or meeting specific uses when necessary.
The coloured glass panels that make up the building’s façade play an active role in the nocturnal lighting system. The beams of light form an irregular pattern as the translucent panels take on colour while passing through the glass roof. These hues combine creating delicate pastel shades.

In the centre of the lobby two vertical panels are flanked by two lines of Philips Color Kinetics iColor Accent Powercore linear fixtures. The vertical lines are brought to life by colour variations in complementary shades, ranging from emerald green to deep blue on the west side and to pale orange and reddish-pink on the eastern side. The transparent lift shaft running up to the auditorium and the business centre is also lit by coloured LEDs.

Visible from the lobby and from the wide public esplanades in the nearby Courbevoie district and in La Défense itself, the bridge-like support structure that sits below the tower is an emblematic sight. At night, the lighting reverses the daytime perception of the building, emphasising the open space created beneath the tower. This is done by using dynamic blue uplighting that accentuates the underside of the building, as well as its side walls and its recesses.

The empty space created by the bridge is flanked and bounded by the coloured light, giving visitors a mysterious, unusual view from the lobby up through the glass roof. The coloured lighting varies very slowly in tone from deep blue to cyan, thanks to variable colour LED floodlights mounted along the walls above the glass roof and on the roof terraces.

The lighting design for Tour Eqho acts to revitalize a building that symbolizes the style of La Défense itself, a modern space with high ideals.


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