Creating Lighting that is More Pleasing to People
A shift toward human preference lighting is driven by a closing gap between efficacy and quality of light
Historically, the commercial lighting industry has been focused on either increasing the efficacy of light sources or increasing the quality of light sources. These concepts have generally opposed each other, resulting in a compromise toward efficacy, typically at the expense of quality. Advances in LED technology, combined with emerging research in human preference lighting, are enabling a return of the pendulum towards the quality of light, providing designers opportunities to enhance environments with better light sources while maintaining high efficacy.
How to measure light quality
Color rendering has long been the main means to evaluate light quality, with the use of the Color Rendering Index (CRI) to produce an average color rendering score. Generally, a score above 80 is considered desired and a score over 90 indicates more red
content and more naturally rendered colors. However, CRI does not provide information on saturation. Also, only eight color samples, which actually do not include a true red, are used to produce the average score. In other words, simply increasing the CRI of a light source does not necessarily mean that the rendered colors will be more pleasant. Lighting researchers have continuously strived to develop new measures for evaluating color rendering.
In 2015, the IES released the TM-30-15 standard to succeed CRI. Akin to CRI, TM-30-15 includes measurements for rendered color. However, TM-30-15 uses three different metrics: Fidelity (Rf), which measures the accuracy of a light source and is similar to CRI; Gamut (Rg), which measures saturation; and a Color Distortion Graphic, which is a visual representation of saturation by hue bin.
In addition to measuring saturation, TM-30-15’s fidelity measurement (Rf) uses ninety-nine color samples, a much broader reference palette than CRI’s eight. Therefore, TM-30-15 data encompasses more color points and provides an improved method to compare a product to its reference source, which at 3500k is a blackbody radiator.
Designing with human preference lighting
Lighting designers have always focused on enhancing the overall quality of light in architectural spaces. As the efficacy of LEDs plateaus, and the design movement toward creating more human-centric environments escalates, designers are now able to create more enhanced spaces and provide more comfortable environments. These pleasant environments allow occupants to perceive more natural skin tones, richer wood tones, more vibrant colors with a light quality that’s truly preferred by humans.
Focal Point has developed Preferred Light, a unique solution delivering enhanced fidelity, gamut and color saturation as measured by TM-30-15. Preferred Light color offers an enhanced light quality that effectively renders colors for human preference; creating more comfortable and visually appealing environments.
Download the white paper to learn more about Preferred Light, a custom LED mix for human preference, and how it is achieved.