New static lightshelf system design of clerestory windows for Hong Kong

This paper investigates the influence of clerestory window structures on the performance of daylighting lightshelves in terms of the interior illuminance level and uniformity distribution using the software TracePro7.0. Simulations were carried out for a window facing south at noon on both summer day and winter day. It is found that a meniscus glazing panel whose curved section is in a meniscus shape can change the light direction and affect daylighting performance. Further results show the best clerestory window structure for Hong Kong is the one whose meniscus section is wide at the top and narrow at the bottom with a curvature angle ranging from 44.3° to 90°. This improves the illuminance and uniformity of the interior space in the winter months (solar altitudes up to 60°) and has a relatively steady effectiveness of around 1.03 in comparison to a vertical clerestory glazing panel. For higher solar altitudes in summer, this structure improves uniformity for the middle and rear room areas by reducing the illuminance in the front, while the effectiveness drops to around 0.91. This is a good improvement which can promote confidence in the application. The proposed structure can be revised and applied in subtropical regions enabling lightshelves to be designed based on their specific requirements.