Energy-Saving Potential of LED Lighting Systems

Abstract

Light emitting diode (LED) with its long lifetime of up 100,000 h has been receiving keen interest as there has been a rapid increase in luminous efficacy of LED recently. One interesting feature of LED is that its spectral power distributions can be easily controllable by regulating electric circuits to LED. Therefore, the same colour from LED can have quite different spectral power distribution due to metamerism. This is important as spectral power distribution is a key factor that can affect human circadian rhythm and subjective responses to changes with different spectral power distribution under the same illuminance level. The study aims to explore the energy saving potentials of LED lighting system by modulating spectral power distributions. The wavelength controllable LED system was developed in the previous study and was used in this study. Dynamic building simulations were carried out in order to quantify the total energy use including energy demands for lighting, cooling and heating indoors. Our study indicates that subjects would tend to feel brighter under red-colour emphasizing spectral power distribution, as compared to their perception under blue-colour. Also, simulation results indicate that total energy consumption can be reduced by 38% by changing spectral power distribution without sacrificing subjects’ visual comfort.