This paper reports a study on visual evaluation of colors under LED lighting operated by an energy-saving control strategy.
Digitally controlled LED systems can produce various qualities of light, adjustable to users' requirements. In this context, a
novel control concept inspired this research: strategic control of Red, Yellow, Green & Blue LEDs forming white light can
further increase energy efficiency. The resulting (more efficient) light, however, would have decreased "color rendering"
(ability of accurately reproduce colors). The notable point is that while reducing color rendering, color temperature and
light levels can stay constant and hence the appearance of the modified light could stay the same, and only the colors of
illuminated objects would change. But how spaces would be perceived under such light with changing color rendering is a
key question. This research investigated the hypothesis that a significant range of color distortions would be unnoticeable
under such dynamically controlled illumination, especially outside of users' main field of view. If successful, such control
technique could be implemented for unoccupied spaces that would not tolerated dimming, and minimize peak hours energy
waste, potentially enabling significant power reductions. Three incremental series of experiments were performed based
on subjective assessment of colors under changing color rendering. Tests were carried out for central and peripheral vision,
using laboratory booths (phase 1) and full scale architectural mockups (phase 2). Results confirmed the fundamental
hypothesis, showing that the majority of subjects did not detect the color changes in their periphery while the same color
changes were noticeable with direct observation.