Experimental Study of Tubular Light Pipe System: Influence of Light Reflector on Its Performance

Abstract

Daylighting is an important passive method of building design in achieving energy savings in buildings. Tubular light pipe system is a modern and innovative technique which utilizes the sunlight to lighten the living space. It is one of the most promising options to provide daylight into deep spaces of not only buildings but also for lighting the road and railway tunnels. The use of light pipe system can save significant amount of energy by providing natural illuminance to interior spaces.In the present study, experimental analysis of light pipe system in Indian composite climate has been carried out. The tubular light pipe of diameter d = 0.23 m and length l = 0.8 m has been installed on the test room on the roof of the workshop block of the Centre for Energy Studies, IIT Delhi. It has been found that by changing the position of light reflector from east to south facing, the daily average of luminous flux and efficiency of light pipe are improved from 31.7 lux and 31.11% to 37.1 lux and 33.40%, respectively. Thus within the range of directions studied, the optimum direction has been identified while providing maximum illuminance to the interior space.In addition to this, importance of tubular light pipe systems in building application has been discussed. Advantages of light pipe over existing artificial lighting systems and energy saving opportunities have also been elaborated elucidating their environmental impacts.