Preferred Chromaticity of Color-Tunable LED Lighting

Abstract

Previous research has demonstrated that individual personal control over light level benefits individuals and organizations. As a first step toward testing whether light source spectrum choices—which are possible with light emitting diode (LED) systems—offer similar benefits, we examined preferences for various spectra in a scale model of an office. Participants judged the model’s brightness, colorfulness, and pleasantness when lit with five preset spectra with measured correlated color temperatures (CCTs) of 2855, 3728, 4751, 5769, and 6507 K created with five LED channels and one fluorescent spectrum (3750 K measured), all at approximately 500 lx. Then they chose their preferred light spectrum using the five LED channels, once as a free choice and once with an illuminance limit. Judgments of the fluorescent spectrum and the LED spectrum with the closest (matched) CCT did not differ. The preset judgments followed a quadratic pattern, with the lowest and highest CCT conditions having lower ratings than the three middle conditions. The free and illuminance-constrained lighting choices did not differ, with individuals’ selections ranging from 2850 to 14,000 K and generally lying slightly below the blackbody curve.

• color quality metrics
• color tuning
• individual lighting control
• light emitting diode
• LED
• office lighting
• personal preference
• spectral tuning

ACKNOWLEDGMENTS

This work was supported by Natural Resources Canada–EcoEnergy Technology & Innovation Fund, Natural Resources Canada–Office of Energy Efficiency, BC Hydro, and the National Research Council of Canada, with the assistance of GO Lighting and Color Kinetics (now Philips Color Kinetics).

The authors are grateful to Naomi Miller, Karen Pero, Lorne Whitehead, and Howard Yaphe for their contributions; to Morad Atif for his support; and to two anonymous reviewers for their helpful comments.