Good light bulbs are hard on the eyes

By Warna Oosterbaan

Energy-saving and LED lights have their advantages, but the decision to ban the traditional incandescent light bulb is "premature", according to experts interviewed.

In an attempt to show their commitment to the environment, EU member states last month endorsed proposals for phasing out the old incandescent light bulb entirely. Following bans in Australia and Latin America, the European Union is expected to make old fashioned light bulbs unavailable by 2012 and ban halogen lights as of 2016.

Lighting experts are worried about the disappearance of the incandescent bulb. They fear that other light sources, such as the compact fluorescent lights (CFL) and light emitting diodes (LED) will deliver a far inferior quality of light. Amongst other disadvantages, these give a less natural reproduction of colours. That has repercussions for households, but also for hospitals, museums and theaters, say technicians and museum specialists. They call the ban on the incandescent light bulb an example of unwanted patronising by the government.

Fans

Incandescent bulbs, which have been spreading light, warmth and coziness in households for over a hundred years, give out, per watt, far too much heat and too little light. And although in the Netherlands these incandescent bulbs only account for three percent of the total electricity consumption, they have been deemed undesirable. The future lies with energy efficient compact fluorescent lights and the new 'wonderbulb': the LED. Both last a long time and use very little energy.

The energy efficient bulbs and fluorescent tubes have already established themselves in the market. Yet the bright LED lamps are not generating many fans. Aren't they a bit - well - bright?

Physicist Tom van den Berg, of the Netherlands Institute for Neuroscience, has conducted a study on just this. The impetus for his research was complaints of boat skippers that they were being blinded by the LED lights on bridges and locks. "It appeared that they were just too bright at night," says Van den Berg. "But fortunately, LEDs can be dimmed easily." The discomfort that many feel when looking at LED lights could be blamed on something else, he says: "it is a different kind of light than we are used to - the light spectrum is different."

This is a sensitive point, as the light spectrum of the traditional bulb is very good. The incandescent bulb - including the halogen - radiates a light that mimics that of the sun. As any rainbow demonstrates, sunlight is composed of many different colours across the light spectrum. Just like the sun, the incandescent bulb uses so-called black body radiation and emits light when heated. Therefore clothes in a store, for example, appear the same indoors as outdoors. In a shop with fluorescent or LED lighting, however, not all the colours are represented: there are 'holes' in their spectrums.

Lighting expert Johan Smits, who gives lighting advice with his agency Light Consult, speaks on behalf of many of his colleagues about what he calls the "hype" around LED lighting. He says the the decision to ban the incandescent bulb is "misguided." He says that "LEDs are suitable in very particular environments. Yet if you want to light furniture, fabrics or art objects, incandescent and halogen lamps are unsurpassed."

Look and taste

Light developer Henk van der Geest, who was responsible for lighting the diamond-encrusted skull made by British artist Damien Hirst when it was on display at the Rijksmuseum (national gallery), says, "in a home environment the incandescent lamps are indispensable. Personally I prefer to eat my steak with a bit of incandescent lighting. It makes it look and taste better."

Physicist Jan Marinus Veltman, a director at Ledexpert, a company that advises clients on potential uses of LED lighting, acknowledges that the colour of the LEDs is not as good as that of incandescent bulbs. "But there will be many improvements coming. The colour-rendering index of an incandescent bulb rates a 100, just like the sun. Yet LED or fluorescent tubes and bulbs only merit between 80 and 90. I think that soon we'll get up to 90 with the LEDs."

A thorny question remains: the energy efficiency of the LED. In 1992 the Japanese physicist Shuji Nakamura was the first to create a blue-coloured LED. This was a major breakthrough, as it brought the creation of a white-coloured LED within reach. By coating the LED with a layer of phosphorous that transforms blue light into yellow, an impression of overall white light emerged. However, this came at the expense of efficiency, which got worse if the led was converted to a more pleasant shade. When adapted to give an incandescent-like glow, the LED bulb in fact performs worse than compact fluorescent light or tubes.

The energy returns can best be expressed in the amount of lumens emitted per watt. A traditional incandescent light bulb emits 17 lumens per watt, a halogen lamp 20. The LED emits up to 50. Yet Veltman predicts that LEDs will conquer the world. "They are getting better all the time, last about 50,000 hours with little energy use. It is a disruptive technology. There's no stopping it."

Hans Wolff, a lighting designer for museums, hospitals and other institutions, worries about the developments: "I will be hoarding the incandescent bulbs and I'd advise others to do likewise."

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