Investigations for the daylighting performance of trapezoid profile shadings using multi-objective optimization

Office buildings present significant potential for energy savings using innovative shading systems, particularly given their extensive daytime usage. However, comprehensive studies that integrate automated shading systems with multi-objective optimization (MOO) to balance visual comfort, energy savings, and daylight distribution are still needed. This research aims to enhance daylighting performance and reduce dependence on artificial lighting by employing MOO techniques. It focuses on automated and split-controlled louvers that adjust slat positions horizontally across the top, middle, and bottom sections of the facade to optimize work plane illuminance under varying conditions. Different illuminance ranges were reviewed for visual comfort in relation to Useful Daylight Illuminance (UDI), with a focus on UDI500 similar to 1000 lx for improved daylighting. The study parametrically modeled automatic trapezoid-profile louver shading devices applied to the climates of Miami, Guangzhou, and Amman. Ladybug Tools, integrated with Grasshopper and Rhinoceros 3D, were used to connect Radiance and Octopus to identify optimal shading solutions. The optimal slat length and angle were determined using MOO based on SPEA2 with hyper-mutation. The fixed exterior trapezoid shadings achieve at least 70 % of the optimal illuminance between 10:00 and 15:00 on typical dates. The newly introduced dynamic louvers, based on hourly openness level for the top, middle, and bottom sections of the facade, achieved at least 98 % coverage within the UDI500 similar to 1000 lx range. Monthly variations suggest that an illuminance uniformity above 0.6 can be achieved, along with 90 % coverage of UDI500 similar to 1000 lx. The Daylight Glare Probability (DGP) index remained below 0.35 for the camera positioned at the back and below 0.4 at the center of the office space, indicating imperceptible and perceptible glare, respectively.