Loving the alien

Today’s low-energy lighting technologies are challenging the conventionally accepted standards of what constitutes ‘white’ light and users will take time to get used to the changing ambience, writes Dominic Meyrick

Aliens have landed. Their multifaceted eyes observe our strange world. With their superior eyesight they note with interest the strange colour of the daylight. Coming, as they do, from a planet with a much ‘whiter’ sun than ours, Earth’s daylight seems yellow and unwholesome.

The aliens’ reaction shows that judgements about exactly what is acceptable white light are subjective: what to one person is a bright and adequate level to another will seem dim.

It is a much-debated topic in the lighting industry and today the debate is increasing in intensity because technological changes are calling into question standards used to determine white light levels.

The brain is able to handle ‘different’ whites because of what is known as ‘colour constancy’. This allows us to experience different day-lit environments, from a bright summer’s day to a dull winter morning, without generally having to be too concerned about the difference in the quality of the light. But colour constancy evolved to allow the brain to cope with the constantly changing colour temperature changes of natural daylight, not the static whites we have to put up with in most artificial lighting.

Lighting designers have long understood the power of installing the right colour temperature in the right situation and, until recently, the limitations of tungsten and conventional discharge technologies meant colour temperature in design was straightforward: 2,700K for ‘warmth’, 3,500K to 4,000K for ‘non-domestic’ settings or 5,500K-plus for a ‘daylight’ feel. So the issues surrounding particular whites for particular areas were often confined to whether the maintenance guys could be relied on to re-lamp with the colour temperature lamps as specified in the design.

But new technologies have blown the situation wide open as they push away the old norms in the name of energy efficiency. Energy efficiency as an objective is, of course, a good thing; but white light must be handled with care. A number of times I have heard users, the most important people in the lighting food chain – exclaim: ‘The light’s so cold!’ and then heard the rebuff: ‘But its low-energy’ – as if this somehow made it all right. Cool light may tick the boxes regarding energy use, but it can miss the mark in terms of user comfort.

This user response to the cooler colour temperatures of low-energy lighting will not disappear overnight, as most of us were brought up in cosy GLS homes and warm SON streets. It could take a generation before high-Kelvin colour temperatures and the typical high blue wavelength content of most of today’s high-efficiency microlamps are accepted as the norm in offices, churches, restaurants and other user-centric environments in which lighting designers work. I leave you with this observation – the colour temperature of daylight changes constantly and, until we develop lamps that do the same, artificial light will not find general acceptance – the public will always find it somehow ‘alien’.

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