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Assessment of Light Shelves as Daylighting Devices in Educational Buildings

Abstract

Adequate daylighting is an important consideration in educational buildings because visual conditions can influence students' concentration, comfort, learning experience, and overall classroom environment. However, excessive direct sunlight and uneven daylight distribution can result in glare, overheating, and visual discomfort. Light shelves are passive daylighting devices designed to redirect natural light deeper into interior spaces while reducing direct solar penetration near windows. Assessing their effectiveness can provide useful guidance for improving daylight performance and reducing dependence on artificial lighting in educational buildings. This study assesses the performance of light shelves as daylighting devices in educational buildings, with emphasis on their ability to improve daylight distribution and visual comfort within learning spaces. It examines factors such as shelf depth, height, position, orientation, surface reflectance, window configuration, and classroom geometry. The study also considers how these variables influence the distribution of daylight between areas close to windows and deeper sections of classrooms, where daylight levels may otherwise be insufficient. The effectiveness of light shelves depends on their ability to reflect incoming daylight toward the ceiling and deeper portions of the room. Properly positioned shelves can reduce excessive illumination near windows while improving the availability of diffuse daylight farther from the façade. Their performance may vary according to building orientation, window-to-wall ratio, ceiling height, surrounding obstructions, and seasonal solar conditions. The integration of light shelves with appropriate glazing and shading strategies can therefore contribute to a more balanced and comfortable indoor visual environment. The study also considers the relationship between daylight performance and energy consumption. Improved daylight penetration can reduce the need for artificial lighting during daylight hours, potentially contributing to lower electricity consumption in educational facilities. However, light shelves must be carefully designed to avoid increasing unwanted solar heat gain or creating excessive contrast between different areas of the classroom. Their effectiveness is therefore dependent on achieving an appropriate balance between daylight availability, glare control, thermal conditions, and energy efficiency. Several challenges may affect the application of light shelves in educational buildings. Limited façade space, construction costs, maintenance requirements, dust accumulation, inappropriate dimensions, and differences in classroom orientation can influence their performance. In addition, external obstructions and climatic conditions may reduce the amount of daylight available for redirection. The study therefore emphasizes the importance of evaluating light shelves in relation to the specific building context rather than applying standardized configurations without considering local environmental conditions. The study aims to provide a clearer understanding of the effectiveness of light shelves as passive daylighting devices in educational buildings. The findings are expected to assist architects, building designers, educational planners, and facility managers in determining appropriate light shelf configurations for improving daylight distribution and visual comfort. By integrating light shelves with building orientation, window design, shading, reflective surfaces, and lighting controls, educational buildings can achieve improved natural illumination while reducing reliance on artificial lighting and supporting more sustainable learning environments.

Keywords: Light shelves, Daylighting, Educational buildings, Natural lighting, Visual comfort, Classroom design, Daylight distribution, Solar shading, Glare control, Energy efficiency, Passive design, Window design, Sustainable architecture, Learning environments.