A Randomized Controlled Trail for Comparing LED Color Temperature and Color Rendering Attributes in Different Illuminance Environments for Human-Centric Office Lighting

Sujung Lee,Heakyung C Yoon

doi:10.3390/app11188313

Abstract

In this study, two experiments were conducted to investigate the effects of the color rendering index (CRI) and correlated color temperature (CCT) of light-emitting diode (LED) lighting on office user acceptance and to explore the proper color attributes for human-centric office lighting. Experiment 1 had four LED lights, with two levels for the CRI (CRI < 80: 79, 76; or CRI ≥ 80: 83, 84) and CCT (3000 K or 6500 K) at 300 lux. In experiment 2, there were four LED lights, with several levels for the CRI (CRI < 80: 78; or CRI ≥ 80: 87, 83) and CCT (3000 K or 6500 K) at 500 lux. Ninety-six participants in experiment 1 and ninety-four participants in experiment 2 performed a reading task. The results in experiment 1 and experiment 2 showed that LEDs with lower CRI values at warm color temperatures were rated as more acceptable than LEDs with higher CRI values at warm color temperatures. However, the positive effect extended to LEDs with higher CRI values at cool temperatures but not to LEDs with lower CRI values at cool temperatures. Therefore, the findings are that LEDs with lower CRI values at warm color temperatures and LEDs with higher CRI values at cool temperatures provide the right level of color attributes for office lighting.

Highlights

Vinh Quang Trinh andThe Commission internationale de l’éclairage (CIE) [1] has proposed integrative lighting
The results revealed that interaction between the color rendering index (CRI) and the correlated color temperature (CCT) of light-emitting diode (LED) lights has an impact on user acceptance
The following conclusions were obtained from the experimental results: LED lights with a CRI < 80 at 3000 K were considered to be more acceptable than LED

Summary

Introduction

Vinh Quang Trinh andThe Commission internationale de l’éclairage (CIE) [1] has proposed integrative lighting. The term “human-centric lighting” (HCL) carries a similar meaning. It integrates both visual and non-visual effects and produces physiological and psychological benefits for people. Light stimulus is processed in visual and non-visual pathways and affects human visual, circadian, neuroendocrine, and neurobehavioral responses. The visual pathway involves a process where light is incident on rods and cones, whereas in the non-visual pathway light is incident on intrinsically photosensitive retinal ganglion cells (ipRGCs) [3,4,5]. The measurement based on the spectral response of the photopigments in the cones, rods, and ipRGC photoreceptors measures the melanopic equivalent daylight illuminance (EDI), while the measurement based on melatonin suppression measures the circadian stimulus (CS). For LED office lighting, Islam et al [16] and Dangol et al [17]

Results

Discussion

Conclusion