Stationary dielectric daylighting louver based on concept of Köhler integrator

Abstract

In this study, a stationary dielectric daylighting louver was developed based on the concept of the Köhler integrator. The developed daylighting louver, which is intended for installation on side windows in mid-latitude areas, such as Japan, is compact and easy to maintain. It was designed to collect sunlight at a solar-profile angle between 20° and 80°, and distribute it with a pitch higher than the horizontal of the room. As the daylight controlling principle, the concept of the Köhler integrator was adopted to capture low-altitude sunlight at an angle between 20° and 50°, corresponding to autumn through spring. The design procedure of the louver and its performance assessment using computational simulations and scale model experiments for office spaces with daylighting louvers installed on a south facade window is presented. The results confirm that 500 lx and more desktop illuminance are maintained at 6 m from the window with only the daylighting device in each season. They also confirm that the high desktop illuminance is maintained even during summer, when the incident angle is large, and the sunlight is difficult to capture.