Evaluation of daylighting effectiveness and energy saving potentials of light-pipe systems in buildings

A light pipe system is a simple daylighting device that allows the natural daylight to enter into interior spaces or underground spaces where access to windows or skylights is restricted. The use of a light pipe system can enhance illuminance without the use of artificial lighting and thus would reduce energy consumption significantly. This paper presents a performance prediction method of a light pipe system based on the amount of daylight admitted and energy saved by not needing electric lighting. The newly developed model was compared with the existing prediction model under the Korean climate conditions, to illustrate the reliability and robustness of the method. Energy saving potential due to the use of a light pipe system was determined with a due consideration of the different artificial lighting control methods (on and off control, two-step control, dimming control), demonstrating a possible saving in lighting energy usage of up to 30% in average. This study should encourage a wider application of light-pipe system in Korea especially in high rise buildings where day-lighting could be limiting; thus increasing the options for architectural design for building application.