Optimal Illuminance of Seven Major Lighting Colours in LED: Focus on Occupant Comfort and Communication in an Indoor Environment

This study aims to evaluate the optimal illuminance for each lighting colour of light-emitting diode (LED) light sources among the seven major lighting colours (red, green, blue, cyan, magenta, yellow and white); the focus was on the optimal combination of these colours for enhancement of occupant comfort and communication indoors. The evaluation of optimal illuminance for LED lighting colours found that the occupants felt the cyan LED light source was similar to a white light source, and that the relative brightness of the green lighting colour was higher than that for other colours. The evaluation of the permissible range of illuminance for LED lighting colours found that occupants believed the red lighting colours to be relatively darker; again, the relative brightness of green lighting was considered to be higher. An experiment with subjects for LED lighting colours (consisting of 19 patterns of 7 colours in the living room of a house) found that the optimal illuminance for occupants' comfort was 32[lx]-119[lx], and for occupants' communication was 107[lx]-584[lx]. These results satisfied the illuminance criteria of Korean Standards as the optimal illuminance for occupants' comfort and communication in the living room.