Identifying the Photometric Characteristics and Applicability of Hybrid Solar Lighting

Abstract

The present research aims at promoting the stability and applicability of a hybrid daylighting system combining daylight and artificial light, which eventually enables a constant and pleasant luminous flux of the mixed light delivered by a terminal device installed indoors. That is, the present system allows a constant amount of luminous flux through its terminal device similar to an electric lamp, demonstrating its energy efficiency as well as comfortableness. The system effectively combines two different types of light, as solar rays are collected by a solar tracking sun light collector. The mixed light is transmitted indoors by optical fiber cables all the way to terminal devices installed indoors and discharged as needed. This feature enables the utilization of daylight to its full capacity, promoting solar availability. In this study, the photometry of hybrid lighting was experimentally measured and analyzed by using a spectrometer for different portions of sunlight when maintaining a constant luminous flux of mixed light. The effectiveness of hybrid lighting was explored for a number of cases in actual conditions, and the system was capable of delivering a constant illuminance of 1200 lux on a plane located 1.1 m away from the terminal device (light emitter). Finally, the system was installed in a test cell to verify its effectiveness for indoor illumination.