The Effect of Curved Light Shelves, Ceiling and Window Characteristics on Daylighting in Thai Classrooms

Abstract

Daylighting is related to the user's psychological and physiological effects in educational space. The amount of daylighting significantly influences visual comfort, work tasks, academic performance and productivity. Thus, proper lighting with sufficient uniform levels of illuminance should be provided in classrooms. Adequate daylight improves visual performance and comfort for both students and teachers, ameliorating negative effects such as eyestrain, headache and lack of concentration. Therefore, daylighting control strategies are important for learning areas. Installing a light shelf improves indoor daylight quality and also offers shading. Many studies have investigated light shelf characteristics, with most addressing flat light shelves. A curved light shelf with a translucent ceiling has not been investigated in Thai classrooms. Window characteristics combined with multiple curved light shelves with translucent ceilings are also understudied. This study investigated the performance of daylight control strategies in classrooms using a combination of a curved light-self, translucent ceiling and various window characteristics. Fifty-five types of daylighting techniques using the existing classroom as the standard were investigated for illuminance levels and daylight uniformity ratio. DIALux 4.13 was used to simulate the illuminance level, while daylight uniformity ratio was calculated under clear sky conditions for a classroom facing east. Results revealed that for all the lighting options, illuminance levels surpassed the standard of 300 lux. A three curved light shelf (outside concave-upward and inside concave-downward) with a 3 m x 6 m translucent ceiling and a 4-horizontal unit with 6-vertical unit window (Option 4.1.3) had the highest uniformity ratio and gave a better result than the other options (0.300) but still did not reach the standard (0.8). Based on this finding, thus, a three curved light shelf (outside concave-upward and inside concave-downward) with a 3 m x 6 m translucent ceiling and a 4-horizontal unit with 6-vertical unit window should be used in classrooms in Thailand and other buildings with similar characteristics.

Keywords

• daylight
• light shelf
• translucent ceiling
• illuminance