Daylighting Design Optimization of Complex Fenestration Systems with External Shading and Horizontal Slats in Tropical Elementary School Classrooms

Abstract

Daylighting in school classrooms is essential to support the health, well-being, and performance of students, while minimizing electric lighting energy. However, excessive exposure to daylight may lead to visual and thermal discomfort, particularly in tropical regions where daylight is abundant all-year long. A popular daylighting design strategy to overcome this problem is implementing the combination of windows with external shading and complex fenestration systems (CFS) in the form of horizontal slats, but its application in school classrooms is seldom discussed in the literature. Therefore, this study aims to optimize the design of CFS with horizontal slats and external shading devices in tropical school buildings with a bilateral opening typology. Computational modeling and simulation are conducted, utilizing the Radiance simulation engine with the 4 PH matrix method. Sensitivity analysis is carried out to understand the impact of window-to-wall ratio (WWR), interslat spacing distance, slat angle, and shading depth on the annual daylight metrics, followed by optimization using the Wallacei optimizer. The first rank optimal design solution is a WWR of 60%, with a slat spacing of 0.2 m and a slat angle of –45° for east and west façades. The optimal shading depths on the east and west façades are 2.0 and 0.6 m, respectively.