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Let there be light

Can luxury be measured with a luxmeter? It certainly can in the case of LEDs. Light-emitting diodes shine wherever design enters the realm of the futuristic. The tiny crystal lamps open up completely new and interactive design possibilities, and that’s with a fraction of the energy consumption of conventional lighting.

COPY/GEORG RÜSCHEMEYER

What is the weather going to be like tomorrow in Brussels? A glance at the 145-meter-high Dexia Tower in the city center provides the answer. If the building is lit up in red at night, temperatures well above the average for the month can be expected the next day, while blue means belowaverage temperatures. The forecast of the Belgian Royal Meteorological Institute for wind, cloud cover and precipitation also sweeps across the facade of the highrise in the form of changing patterns and colors. The “Weather Tower” as an XXL weather map is just one of multiple interactive lighting installations by the artist group LAb[au] on the building’s facade. “Chrono Tower” uses color to represent the passage of time throughout the day; “Touch” allowed passers-by on the street to create their own colors and patterns on the building using a touchscreen connected to the control computer. Making this oversized, dynamic screen possible are more than 150,000 green, blue and red LEDs in the windows of the building. Whether interactive art or targeted lighting design, a veritable quantum leap in light-emitting diode technology (see technical information on page 28) has enabled the tiny semiconductorbased light sources to become a driver for sophisticated lighting architecture the world over in recent years, particularly when it comes to lighting concepts that stray from the beaten path. The wide color palette of LEDs allows for extraordinary color accents; their small size and low maintenance requirements open up new possibilities in design. The latest generation of LEDs stand out for their durability and, for the same light output, use only a fraction of the energy required by conventional lighting. This makes even the transformation of entire buildings into spectacular light installations an acceptable luxury with respect to energy. It’s no wonder that star architects the world over are incorporating the nearly endless possibilities of LEDs into their designs. The New York-based architectural office Asymptote Architecture used a mesh of some 5,800 glass panels to cover the YAS hotel which sits astride the new Formula 1 racetrack in Abu Dhabi. At night it is transformed into a spectacular lighting display made up of thousands of LEDs shining in all directions. These little light-emitting diodes also accentuate the Torre Agbar in Barcelona, which is modeled on a geyser. The 32-story office complex by the French builder Jean Nouvel has highlighted the center of the Spanish metropolis since 2005. The patterns of colors moving dynamically over the building’s surface symbolize the elements of fire and water associated with a geyser and appear to free the building from gravity’s grasp at night.

Internal illumination also characterizes the new Ars Electronica Center that opened in Linz, Austria, in early 2009. “I was striving for a sculptural building whose structure could be walked on and thus experienced sensually,” says its creator, the Viennese architect Andreas Treusch, when explaining the idea behind the design. This concept is also reflected in the double-shell facade, which can be illuminated in a number of colors using LEDs and joins the new building and the existing festival building to form a complex cube of steel and glass. “This turns the building as a whole into an over 5,000-squaremeter projection and image surface, a transparent light sculpture with high recognition value.” The New York media artist Zach Liebermann demonstrated what possibilities this opens up with his “Lights On!” audio-visual performance at the opening of the center. Liebermann’s interactive installation coupled flashes of light running over the entire building with spherical computer-generated music broadcast on loudspeakers surrounding the building. Artists like Liebermann are pioneers of an interactive lighting design for which LEDs are predestined because of their flexibility in terms of color and intensity. However, the trend in practical lighting design for interior spaces is also moving in the direction of interactive illumination concepts that combine natural and artificial light to adjust dynamically to people’s requirements. At workplaces, for instance, which in keeping with the latest findings in perception psychology are bathed in indirect, nonglare light whose intensity and color changes over the course of the day. “This supports the natural cycle of the wake and sleep hormones, for instance by using intense white light in the morning to stimulate the production of serotonin, whereas, for example, a room bathed in warmer tones in the evening tends to signal the brain to relax,” says Christian Bartenbach, founder of the world-renowned Bartenbach Light Laboratory outside of Innsbruck and a pioneer of modern lighting planning. Bartenbach prefers to leave lighting during the day to the natural dynamics of sunlight and uses natural daylight whenever possible to light interiors, even in large projects such as the new construction of the Grand Egyptian Museum in Cairo. But what do you do when night falls? “All of these projects use LEDs whose intensity and color spectrum most closely resembles daylight,” says Bartenbach. The small dimensions of the LEDs are also important to the senior ambassador of lighting planning, however. “Until now I always had to consider how to conceal large lamps or how to integrate them into the architecture. LEDs allow the individual light sources to be decentralized; the construction material itself shines.”

The new LEDs appeal not only to architects, but also to the designers at Audi, for whom the subject of light has always been a part of their core business. “We certainly draw ideas and inspiration from the intelligent lighting concepts of modern architecture,” says André Georgi, the designer responsible for lighting systems at Audi. The Ingolstadt carmaker was also the first in the industry to recognize the enormous potential of LED lighting technology. Audi introduced LED daytime running lights in 2004, which have since become a brand trademark. The R8 has been available with headlights based exclusively on light-emitting diodes since spring 2008, and the flagship of the Audi fleet, the recently introduced new A8, can also be ordered with full LED lighting. “That gives us a four to fiveyear head start on innovation,” says Dr. Wolfgang Huhn, Head of Light and Visibility at AUDI AG, as he demonstrates the structure and function of the latest-generation full LED headlight with 76 LED light sources in his research laboratory. Technically impressive, highly aesthetic and a textbook example of an eco-innovation, as LEDs are hard to beat when it comes to energy efficiency. A car equipped with conventional halogen lights uses an average of 130 watts of energy. This energy is provided by the alternator and thus is reflected in higher fuel consumption. The systematic use of LED lighting reduces this value to roughly one third. “The difference corresponds to nearly a quarter liter of gasoline per 100 kilometers. That doesn’t sound like much until you extrapolate it out to many millions of cars and kilometers driven,” says Huhn. The difference is particularly dramatic with daytime running lights, which will be mandatory throughout Europe starting in 2011. A conventional low beam headlight consumes 10 to 20 times as much energy as the LED daytime running light on an Audi.

But low power consumption is far from the only advantage of LEDs. The future belongs to headlights that think with the driver. “An intelligent, active exterior lighting system plays an important part in the prevention of accidents which occur at dusk and after dark,” explains Huhn. As daytime running lights, for instance, LEDs help to increase visibility to other drivers. LED brake lights facilitate a faster response. “Here, too, we are talking about the seemingly insignificant difference of a few fractions of a second. But at high speeds, that can mean a difference of several meters in stopping distance,” adds Huhn. Their small size also makes LEDs particularly well suited for use in adaptive front lighting systems such as the dynamic headlight range adjustment or cornering lights because they also enable complex lighting functions in the tightest of spaces. The Audi brand taps into the potential of the new, increasingly powerful LEDs to turn its vision of intelligent light into reality. Currently in development is the “MatrixBeam” virtually no-glare high beam, whose cone of light is produced by a multiplicity of LEDs. When the system’s onboard camera detects an oncoming automobile, those modules that could blind the driver of the other car are dimmed automatically. André Georgi also appreciates the new freedoms when developing a distinctive lighting design. “Just like every person’s eyes are unique, so too are the headlights an unmistakable characteristic feature of a car,” says the Audi designer. “A glance in the mirror at night should be enough to tell you: That’s an Audi coming!”

The special color of the light modeled on the spectrum of the sun and the shape of the daytime running lights, which emphasize the contours of the headlights with individual light-emitting diodes – just as eyeliner does for the human eye – make an unforgettable impression. “And each Audi model features the lighting design that best suits it,” adds Georgi. The daytime running lights of the R8, for instance, were inspired by the horns of a bull as a symbol of the dominant character of the model. The LED strips of the A3 model series, on the other hand, symbolize determination and elegance. LEDs also set accents and ensure an outstanding lighting environment at the driver’s “workstation.” “When entering the vehicle, you are first welcomed by warm, bright light from the interior of the vehicle,” says Stephan Berlitz, Head of Innovations/Lighting Electronics at Audi, when asked to explain the optionally available interior lighting concept of the new A8. The color and distribution of the light can be adjusted to taste using the vehicle’s multimedia interface. “In the end, our job is hardly different from that of a lighting planner in architecture. Everything revolves around the person, whose needs for functional and at the same time appealing and stimulating light must be met,” adds Berlitz. With the LED, architects and carmakers are now banking on the same technology as the light source of the future. It’s no wonder, since no other form of lighting appeals equally to the head and the emotions, and makes something so practical seem so sensually luxurious.

TECHNICAL INFORMATION

LEDs, standing for light-emitting diodes, are tiny semiconducting crystals that convert electricity directly into light. LEDs enable the temperature and the color spectrum of the light to be changed. The light’s color is determined by the choice of the semiconductor material and targeted contamination with foreign atoms such as phosphorus or gallium. For decades LEDs led a niche existence as red flashing lights in electronic devices, but in the meantime there are high-efficiency LEDs ranging from infrared to ultraviolet. Furthermore, LEDs can be embedded in other materials. The latest generation of LEDs, such as those found in current Audi models, have a service life of up to 50,000 hours and are practically non-wearing. They now yield 50 lumens of light power per watt of electricity applied. In comparison, an incandescent bulb achieves less than half of this value. There is still plenty of untapped potential in LEDs, however. It is only at around 350 lumens per watt that all of the electrical energy is converted into light.