Findings from Daylight Simulations on Straight and Elbowed Light Pipes

Light pipes are one of the most effective methods for transmitting daylight into deep interior spaces. To adapt to complex building structures, it is recommended to use one or more elbows to redirect the light. However, it is essential to determine the light losses caused by adding elbows to the system, especially when compared to straight pipes of the same length. This study primarily aims to test different elbow configurations on light pipes. Additionally, it seeks to evaluate the efficiency trends associated with varying lengths of both straight and elbowed light pipes under the same configuration. Validated simulation tools and plugins, known for their accuracy, are employed as the primary method in this analysis. The core software suite includes Rhinoceros for 3D modelling, Grasshopper for algorithmic graphic editing, and Ladybug and Honeybee plugins for daylight simulation. Different configurations were analysed under clear and overcast sky conditions, based on maximum and average illuminance levels on the working plane. The results revealed that straight pipes with a short aspect ratio provided the highest levels of illuminance but caused glare on the working plane under clear sky conditions. For double-elbowed pipes, light losses increased significantly with pipe length compared to other typologies. But it was found that under clear sky conditions and in spaces where lower illumination levels are sufficient, the system performs adequately when the light transmission direction is deliberately altered.