The effects of illuminance, colour temperature, and colour rendering of various existing light-emitting diode lamps on subjective preference and performance in Indonesia

Studies on user acceptance of Light-Emitting Diode (LED) lighting were largely done in developed countries, while there are presumably significant differences between the developed and developing countries. Series of measurements of various domestic LED lamps in Indonesia were conducted to investigate the effects of varying illuminance (Eav), Correlated-Colour Temperature (CCT), and Colour Rendering Index (CRI) on visual perception and to determine the users' preference of those parameters in Indonesian context. Visual assessments were conducted using observation booths in a dark room. The assessments were consisted of subjective performance and preference tests. The performance tests focused on the subjects' acuity in reading letters with various size and contrast; while the preference tests focused on the perception of lighting level, colour clarity, colour appearance, and overall visual comfort. It was found that variation of CCT yields significant effect on colour clarity and visual comfort. In term of colour appearance, variation of CCT yields more significant effect compared to CRI, while illuminance gives no effect. On lighting level, variation of both Eav and CCT yields more significant effect compared to CRI. Most of the participating subjects felt visually comfortable under the CCT of 6500 K, average desktop illuminance of 350 lx, and higher CRI value.