A Novel Louver System for Increasing Daylight Usage in Buildings

Advanced daylighting systems can be effective in increasing light levels in building spaces and reducing energy consumption due to electric lighting. However, a recurring issue found in most existing daylighting systems is the necessity of coupling the light-redirecting technology with a separate light shade to reduce glare risks. A different approach is proposed here, based on the use of a louver system which scatters incoming light onto a reflective ceiling, where it is redirected deep into the space. This type of system is effective for both diffuse daylight and direct sunlight without causing glare and without the need for a shading system. Annual simulations of workplane illuminance were conducted with Radiance using Tokyo weather data and a generic south-facing deep-plan office space. Glare was evaluated through testing of a physical prototype of the system. The new system was compared to a base case consisting of an unshaded window of equal area to the louver system. The results show that the novel louver system enables a significant decrease in electric lighting usage and outperforms the uncovered window, while adequately controlling direct sunlight to prevent glare.