Evaluation of Energy Savings of Daylight-Linked Lighting Control Strategies Using Different Sky Distribution Models

Among all components of building energy use, the energy consumption caused by electric lighting can account for more than one quarter. Daylight are more preferable than artificial lighting since its quality is the one light source that most closely matches human visual response. Daylight-linked lighting control strategies can effectively reduce the electricity consumption of lighting. The daylight illuminance inside and outside a room are largely determined by the sky luminance distributions. However, the actual sky conditions are more complicated because of the changeable weather. The sky luminance distributions models could be very helpful for predicting the sky conditions. The Perez All-weather model and the CIE (International Commission on Illumination) Standard Sky model are the two most famous and widely used approaches to provide a framework for representing actual sky conditions. This study aims to evaluate the energy saving potential of daylight-linked lighting control strategies using the above models. RADIANCE was used as the simulation engine for daylight illuminance, while EnergyPlus was used to evaluate the energy savings. The simulation results of vertical illuminance were analysed and compared with the measured data. Lighting schedules derived from the interior daylighting levels were imported to the energy models. Results showed that at least 55% lighting energy and 9% cooling energy reduction can be achieved using daylight dimming controls based on the two sky luminance distribution models. The findings and implications were discussed.