Development of Rolling Type Light-Shelf with Adjustable Reflectivity

반사율 변경이 가능한 롤링타입형 광선반 개발

Purpose: Recently, lighting energy consumption in buildings has been gradually increasing and more studies are being carried out in order to solve this problem. Especially, the efficiency of the light-shelf system, which is a natural lighting system, has been recognized as a potential solution in addressing this problem and so various studies regarding the light-shelf system are being conducted. However, if high luminance material is used for the light-shelf system, glaring may occur in certain circumstances even though such material increases efficiency, and there are also difficulties related to maintenance and management in the case of an external light-shelf system. Therefore, the purpose of this study is to suggest modifications in relation to the reflectivity of the light-shelf system and introduce a rolling type light-shelf system with built-in cleaning equipment. In addition, a performance evaluation technique was established to verify its effectiveness. Method: In this study, we reviewed previous studies related to the light-shelf system and its performance. Then a testbed was established to assess the performance of the rolling-type light-shelf system suggested in this study. Also, the performance of the rolling-type light-shelf system suggested in this study was compared and analyzed with that of existent light-shelf systems in order to better verify the performance, and the uniformity ratio of illumination and lighting energy consumption were calculated for this purpose. Result: The results of the performance evaluation are as follows. 1) The performance evaluation result of the light-shelf system on the day of the summer solstice shows that $30^{\circ}$ is appropriate for the angle of light-shelf system, and the depth of the incoming natural light also increases as the angle of the light shelf increases. 2) It is possible to improve the uniformity ratio of illumination by increasing the reflectivity of the light shelf, and the reason for this is the increase in the amount of incoming light entering indoors due to the increased reflectivity of the light shelf. 3) The rolling type light-shelf system suggested in this study enables energy saving in comparison with existent light-shelf systems, and when the external illuminance decreases to 60,000 lx and 40,000 lx during the summer solstice due to factors such as the weather, the suggested light-shelf system can save energy by 12.1% and 5.1% respectively. Thus the light-shelf system proposed in this study is deemed to be effective in reducing energy costs.