Illumination
The building has a total of 6,000 windows.
Behind each of 4,200 windows there is a lighting installation consisting on average of 12 light bulbs, each with three LEDs – a green, a red and a blue - that can be combined into a complete colour palette.
A rapid change in the colour of the lamps instantaneously gives an impression of movement.
Copyrights* - Pictures Marc Vanderslagmolen Light artist : Arto
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The façade can show figures, letters, geometric shapes with various effects and also graphic designs.
The combination of green, red and blue produces white.
To start the lighting system, all blinds should be closed as the leds are not strong enough to light the façade alone.
The reflection on the closed blind illuminates the whole surface of the window.
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If the blind remains open, you only see a horizontal light line at the bottom of the window.
When the illumination system is working, all the sun-blinds close automatically. This is necessary because the colours are reflected off them.
The system is controlled by a central computer. The resullt is entered in a programme to be translated for the lighting system by the computer.
An image, a visual effect or letters are only visible when some windows are lit in some colours. This means that each of the 4,200 windows equipped with the system can be illuminated separately and exactly in a given colour. This produces the image or the animation you can see.
Technics
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A central computer translates the effect to be shown, image per image.
For each window, the calculation gives the exact colour in order to display the result on the façades.
The data are sent through a rapid computer network to three distribution centres spread out on the various floors of the tower.
These centres translate the data for groups of about 100 windows.
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These data are then distributed to the 100 footlights of each group, which will receive their individual data through a small integrated computer.
They will then determine the proportion of red, green and blue necessary to obtain the colour wanted for this particular window.
The supercomputer calculates more than 20 images per second and each of the 4,200 windows has such a small computer to check the colour to be displayed about 20 times per second… for a unique result!
Principles for use
The tower is a building with three illuminated façades, which is visible both in the neighbourhood and in the distance.
It is integrated in the city like an urban signal and contributes to the international image of Brussels.
Dexia wants the tower to be an urban sign through its architecture and the presentation of works of art and events. The three main projects for using the building in this respect are:
- a permanent illumination (the present RGB project)
- an original creation every year (ex. Touch project in 2006)
- a participation in a limited series of national and international events.
Consumption
The Dexia Tower is equipped with a highly effective energy-saving LED lighting system (electroluminescent diods).
Each led, at its maximum capacity, uses 1 watt. As a result of the various colour and movement effects, this maximum capacity is never achieved. The different creations presented so far have never exceeded one third of this total capacity.
During the night, the tower is illuminated 9 hours in the winter and 5 hours in the summer.
Recent tests reveal that the Dexia Tower uses about a third less electricity than the Eiffel Tower in Paris, while the energy required to light a football stadium costs no less than seven times the energy consumed by the Tower.
*Picture copyrights : Architects : Philippe Samyn & Partners, M & J.M. Jaspers - J. Eyers & Partners | Lightning engineer : Barbara Hediger
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