| Keywords |
Daylight illuminance ; Photoelectric dimming control ; Sky conditions ; Fluctuation of daylight ; Sky ratio |
| Abstract |
This study examines the variation range of daylight illuminance in winter in order to apply photoelectric dimming control systems effectively with stable light output from lighting fixtures. Field measurements were performed in a full-scale mock-up space under various sky conditions. Results imply that the fluctuation of daylight illuminance under sky conditions except overcast sky significantly influenced the variation of indoor illuminance. The absolute value of fluctuation range of sky ratio was within 0.1 under overcast sky. The fluctuation range of photosensor illuminance under partly cloudy sky was greater than that under overcast sky conditions. This means that the electric light was controlled unstably due to the wide range of fluctuation. Outdoor vertical illuminance functioned as an effective variable that can be used to predict the fluctuation of photosensor illuminance, when photoelectric dimming control systems were used for lighting control in space. |