Transparent Shading Device as Daylighting System

Most shading device systems installed in windows or glass walls are used only for protection from overheating and glare, neglecting other possible functions, such as increasing the daylight level in the space or collecting solar energy. The blinds are usually made of opaque or translucent materials, and if they are partially or completely closed, a direct view to the outside is blocked. A balance between a sufficient amount of daylight and protection from overheating of the space in summer is not often achieved due to inappropriate control of the blinds’ tilt angle. This paper explains research that had the purpose to study daylighting performance of a transparent shading device as part of a window system. The objective of the research was to propose a new design of transparent shading device with improved daylighting performance. A new shading device system has the triangular cross section of the blinds. Application of the clear plastic and silver reflective coating as the materials for the new blinds utilizes the principles of optical physics in the design. A case study was performed to analyze daylighting performance of the new transparent shading device system, an existing opaque system, and a patented transparent system. Daylighting performances of the three shading device systems were compared to select the system with the best performance. The paper presents results of daylighting simulation of the three systems installed in the curtain wall at a proposed office building located in Roanoke, Virginia. The output of simulation is actual values of illuminance and luminance in the space obtained by the application of the different shading device systems. Comparison of the daylighting performance for the three shading device systems showed that the new system seemed to provide the highest level of daylight in the space, given the limitations of this study. Being made of transparent material, the new shading device system also provides transparency of the window/curtain wall.