Light colours in retail

Delivering high light quality is essential for a premium luminaire manufacturer. In retail, colour rendering is the decisive feature, along with accentuation and intensity. Since 2020, most spotlights have the improved colour rendering of Ra≥90 instead of Ra≥80. Full-spectrum light colours with an excellent colour rendering value of Ra 98 are available via a separate request under the company's internal XPECTRUM designation. To reflect this outstanding light quality in the data sheets, the Re value is also listed for all XAL luminaires with Ra≥90. The Re value is the average value of the 15 test colours of the international colour rendering evaluation CIE 13.3 (1995). Only the Re-value enables quality evaluations to the highest level.

International lighting designers expect colour rendering ratings according to the American TM30 method. Therefore, the Rf and Rg colour ratings can also be found on the XAL data sheets of luminaires with Ra≥90.

The XAL colour chart

The eight test colour samples, whose mean value results in the colour rendering value Ra, are hardly suitable for the optical comparison of light colours. To recognise differences in visual performance, saturated colour samples are needed. The four saturated CIE 13.3 test colours R9–R12 are suitable for this purpose. In addition to saturated red, yellow, green, and blue, we chose cyan, purple, brick red, and the test colour R8 light reddish purple. The display capacity of different spotlights is identifiable with these eight saturated colours. XAL's new colour chart is rounded off with white rendering pastel areas in the upper left corner to show the white rendering capability. For saturation we chose 2% in red, yellow, green, and blue. On the right, a grey rendering is added to show the display capacity of grey and black.

XAL COB recessed display points

In XAL’s Graz headquarters showroom, we make lighting quality tangible. Twelve light colours can be controlled via a tablet using a DALI signal. Upon touching the tablet’s touch screen, the buttons for the pre-set scenes appear. The drop-down menu contains the light colours 3000 K, 3500 K, and 4000 K, each in Ra 90 comparable with Ra 97. On the left-hand side of the tablet, all left or right spotlights can be switched on. On the right-hand side of the tablet, one can switch between three Ra 90 and three Ra 97 spotlights. The high-end light colours BRILLANT and GALLERY can be compared, and "Tunable White" can be compared with "Colour Warm Dimming".

The touchpad surface, allowing comparison of the twelve light colours.

Two spotlights are installed in each recessed display point. Below each spotlight are a light colour description, spectrum, and colour rendering bar graphs indicating Ra and Re values. The spotlight type label can be read from a few meters’ distance. A status LED shows which spotlight is switched on.

Quality of light

Experiencing light colours is impressive. The effect of the test colours under different light colours can be experienced in XAL’s showroom in Graz. XAL offers the light colours 2700K, 3000K, and 4000K in Ra ≥90 as standard for retail spotlights. In addition, CWD (Colour Warm Dimming) with 1800 K–3000 K and Tunable White with 1800 K–3000 K and 2700 K–6500 K are offered. A range of special light colours such as Brilliant, Gallery, and Vogue are available for high-end retail. Furthermore, we can also supply three product-specific light colours, Pastry, Meat, and Meat+, for delicatessen counters in the food trade on request. Let's enhance retail products with high-quality light colours together.

Colour Warm Dimming 1800–3000 K Ra = 93, Re = 90

CWD consists of two light colours. When dimming, the colour temperature changes at the same time. The colour temperature is dimmed continuously from 3000 K to a very warm white 1800 K with a significant reduction in intensity. CWD is suitable for products with a high red component as well as for creating adaptable atmospheres in hotel lobbies or lounges.

PASTRY 2700 K–6500 K Ra=90, Re=87

This lamp has two light colours. All colour temperatures lying in between can be individually adjusted via a controller. 2700 K is suitable for yellow-red-heavy surfaces from gold jewellery to wood colours, or, for example, also for pasta. 6500 K is ideal for blue-white-heavy surfaces. Perfect for a jeweller with changing pieces of gold or platinum jewellery.

Colour Warm Dimming and Tunable White can have different effects.
Colour Warm Dimming and Tunable White can have different effects.