Experimental research on daylight performance of side lighting light pipe

Natural daylight has more and more been used in modem buildings to save building energy consumption in China. Light pipe is one of the effective way to reduce electricity consumption for lighting, it can transmit light from outdoor to the room without generating excessive heat. Experimental apparatus of side lighting light pipe is described in this paper. Light pipe for side daylighting purpose was installed in the Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education, Beijing University of Technology. It was 2.6m long, with diameters of 360mm.The performance of the light pipe for whole day had been measured. The highest iUuminance was 488lux on Dec.26,2002, obtained from the point beneath the center of the diffuser of the light pipe 1450mm. The ratio of internal illuminance to external was 0.23 %. Because it has many advantages to improve energy efficiency in buildings, light pipe will be populanzed in the near future in China.