Daylight Performance of Elbow Geometry in Light Pipe Models

Abstract

Light pipes are innovative daylight lighting systems often used linearly which transmit light through reflections on carrying surfaces. However, in order for the system to be used in more complex buildings, it should be possible to integrate one or more elbows into the system if needed with the purpose of deliberately change the direction of light transmission. In this study, attention is drawn to the assumption that the light carried in the elbowed light pipes is related to the design of the elbow geometry as well as variables such as pipe length, diameter (aspect ratio), reflectance and transmittance values of the components, sky conditions, solar angles, latitude-longitude data, elbow angle, etc. The purpose of the study is to investigate the daylight performance of elbowed light pipe system and different elbow geometries. In this respect, the models used in scientific studies and commercial products were compared and new elbow models were proposed. Daylight levels (lux) and Daylight Factor (DF) achieved through a numerical simulation software based on a correct method and well-established algorithm were evaluated as performance measures. Whether the light levels reached as a result of the analyses alone are sufficient to illuminate the space varies depending on the dimensions, function and duration of use of the space.