Colourising daylight in buildings: Visual responses in a daylit room supplemented with colour-changing light-emitting diode luminaires

Abstract

This research proposes the use of colour-changing light-emitting diode (LED) luminaires to supplement daylight for more sensory working or living environments. An experiment was conducted to examine a room lit by a mixture of natural light from window walls and artificial light from LED luminaires which could be programmed to produce four colour lights: orange (correlated colour temperature around 2000 K), yellow (around 3000 K), green (around 7000 K) and blue (around 8000 K). Participants were required to answer questions pertaining to function (naturalness of selected objects) and sensation (brightness, relaxation, pleasantness and interest). Generally, when daylight was mixed with warm colour, such as orange or yellow, the room was more interesting. Further comparison pointed out that the green light might have a negative effect for daylight perception. The most important finding is that when daylight was supplemented with the blue LED luminaires, the room was most relaxing, pleasing and natural, which was preferred by participants. The findings of this research would inform architects, designers to decide on how to use coloured luminaires as a supplementary light source for daylight to enhance sensory experience in buildings.