Enhance the Reds in Interiors: Understand R9 in LED Lighting

Red is for passion, love and seduction. It can mean danger anger or adventure. Our distant ancestors saw red as the colour of fire and blood – the very essence of life. For all of these reasons red is engrained in us and these instincts contribute to make red the most important colour. It is no less important in our interiors. Yet the LED lighting revolution has struggled to produce a white light that makes reds rich in colour, often making russet, mahogany, ruby and scarlets appear flat and lifeless. Now, a new wave of LED lamps is emerging and a new scale of colour calibration has been adopted to help us gauge how vibrantly solid state lighting illuminates our designed spaces.

Reds Make Colours More Vibrant in Your Interiors

Richer Reds make all colours more vibrant and whites a truer white. This helps to enhance interior designer’s creations and compliment furnishing choices by showing a full spectrum of colour within fabrics and materials. Colour accuracy of soft furnishings and wall coverings can be adversely affected by the imprecise rendering of the colour red.

What is CRI R9 Value in LED Lighting?

The old CRI scale is calculated on average values based on R1 – R8 coloured swatches. Here is where the ‘LED colour blind spot’ occurs. R9 is one of six saturated test colours not used in calculating CRI. Note that on the CRI calibration below R9 is not measured.

Why Understanding R9 in LED Lighting is so Important

However, R9 is important when assessing the quality of LED light. It seems that most LED sources reveal this CRI value only and as long as it has a value of over 80 Ra. In other words, LED lamps with high R9 values to produce the most vivid colours that are essential for professionally designed interiors an retail display application. However, we cannot rely upon the traditional measurement chart to judge the level of R9 in a LED lamp.

So it is time for a new metric compatible with our LED world. Scientists at the US-based Illuminating Engineering Society have developed a new system commonly called TM-30 which is based on a reference set of colour samples that is more representative of objects in the real world than the pastel samples used in CRI. A Rg value will repl

ace the existing Ra and it will accurately score LED lamps for colour ‘red’ accuracy. The new measurement has been approved in the US although it has yet to be accepted by the CIE – lightings international body.

TM-30-15 as the New Colour Rendering Index

In replacing CRI, TM-30-15 offers a new way to evaluate the colour of a light source by measuring the fidelity (match to a reference) through a Rf fidelity reference and a gamut value Rg indicating thestrength of the apparent chroma.

How to Improve the Red Colours from LED Lighting

A number of products have become available – both in lamps and luminaires. At the higher end – we recommend a new luminaire that promises richer reds. The downlight features a new chip that delivers almost 100% across all R categories – major step in the right direction – toward a perfect lighting scheme.

The product is priced at a premium so we offer the original version of the fixture too.
We also supply an excellent GU10 spotlight by Integral LED – Real Colour that has a high CRI (95). For a small extra outlay of budget, it will make your reds pop and your pinks sing!

So it is time to embrace vivid reds in your next interior project. They may be a little more expensive now – but we predict – it is a step that will soon become standard. Call us for more details!

Andrew Orange, the owner of Orange Lighting qualified and worked as an interior designer in 1993 before specialising in lighting working on high profile projects based in London. Since starting Orange Lighting Ltd in 2003 he has been sharing his knowledge and unique teaching style mostly to his designer clients, offering practical real life advice born from running a busy consultancy and lighting supply business. Launching in 2020, his blog has evolved into Quick & Easy Lighting, curating some 25 years design experience into making the lighting choice and design process achievable and easy to understand for all.