Daylighting performance simulation and analysis of translucent concrete building envelopes

A novel optical fiber (OF) embedded building envelope, namely translucent concrete (TC), was proposed and popularized for its light transmission property and unique artistic features, but there is still a lack of in-depth research on its daylighting performance analysis. To reveal the impacts of multi-factors on TC daylighting performance, an optical model of TC was established based on a ray-tracing method. In the model validation, both the simulated transmittance of OFs and illuminance of translucent concrete were in a good agreement with the experimental results. The simulation results showed when the numerical aperture (NA) of the OFs increased from 0.51 to 0.70, the annual average luminous flux of TC under seven cities conditions could be enhanced by up to 40.62%. In terms of effective illuminance, the optimum fiber volume ratio of the seven cities was determined, respectively. Besides, it was found that the core-cladding interface losses could lead to a relative deviation over 5% when the length of 1-mm OFs with 0.51 NA exceeded 259 mm, and the deviation could be larger with the decrease in diameter of OFs and the increase both in length and NA of OFs. (C) 2020 Elsevier Ltd. All rights reserved.