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Shining a light on colour rendering

On July 12, 2017
On July 12, 2017

Without realising why, or even considering lighting as the problem, consumers naturally shy away from buying products in a retail environment with poor quality lighting. Studies conducted around the world have shown a marked difference in the sales performance of retailers with high quality lighting as opposed to those with cheap, poor quality versions of the same technology.

That’s as a result of colour rendering – the ability of a light to emit and then reflect a full spectrum of colours.

The traditional LED technology to create white light has a blue LED light source. “It incorporates a blue sapphire-based chip combined with a mix of phosphors. When the blue light hits that phosphor, it re-emits as a visible white light”, KKDC’s Carl Moselen says.

“What makes this different from traditional light sources is that manufacturers often have their own variations and tolerances within these two products; the blue chip and the phosphors, this can result in colour and hue variations.

So, if you’ve got lights installed in the same area made by five different manufacturers, you could have five different looking lights in that room, despite being quoted as the same colour temperature, or worse still, variations within the same product.”

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Knueferman Store, Photography by Frank Coyle

There are complex measures to evaluate the qualities and effectiveness of a light source, including the well-known Colour Rendering Index or CRI. The CRI measures how well a light source renders a specific set of colours based on 14 colour samples. The first eight in the set are pastel colours, and nine to 14 are colours of special significance incorporating skin tones and organic materials. These are then averaged to a single value: Ra

Recently, the CRI system has been re-evaluated, and new standards are being adopted to more accurately quantify light quality. For example the recent development of TM-30-15 includes 99 different colour samples, and measures for hue and chroma.

“Roughly speaking, an incandescent lamp and natural midday sun will have a CRI of 100” Carl says. “Traditional Linear LED technology sits around 80CRI.” Having a lower colour render means that you’re potentially missing critical parts of the spectrum and therefore some colours won’t be truly represented under that light source.

While industry leaders have lifted this benchmark to 90+CRI using existing technology, including KKDC’s Ultra line at 98CRI, there is still room for development in tailoring a product for specific applications.

Traditional technology, which is now widespread, has also always been weak at the violet end of the spectrum and remains that way in the case of the majority of global manufacturers of this type of LED lighting. “The violet end of the spectrum is the area that relates to the illumination of different whites, which is an important part of the colour spectrum, particularly in many professional and retailer settings,” Carl says.

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Fonterra Head Office, Auckland CBD, Photography by Simon Devitt

This next generation of Linear LED lighting known as N-Line was designed specifically for the illumination of whites and incorporates a violet chip rather than a blue chip so you can see subtleties within a range of whites. It opens up a whole new colour palette at this end of the spectrum.”

While it may not sound like anything extraordinary, colour rendering is a critical part of many situations, particularly in the commercial, retail, scientific and medical sectors where the importance of being able to define subtleties in colours is crucial.

“For example, in a shop fit out designed for a wedding dress retailer, you’re going to want to see the intricacies of slightly different shades, just as you might when you’re in an art shop purchasing paper, or in a medical or scientific environment when you need to determine between subtle variances in white.”

“Depending on the context, the implications of a poor quality light source can range from lost sales through to safety issues. At the end of the day, particularly in commercial projects, it’s about the bottom line. What we’re finding is people aren’t educated about the benefits of good lighting and aren’t aware that buying a poor quality LED won’t allow for the full spectrum of colours to be visible.”

Get in touch with KKDC on ArchiPro here to discuss your lighting needs and how to achieve the optimum Linear LED solution.

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