Keywords: light pipe system, daylight, daylight penetration factor, energy consumption, semi-empirical model, underground parking carpark.

Light pipe systems bring daylight into hard-to-reach interior space. By using light pipe systems, the illuminance level can be increased without the use of artificial lighting thus daytime energy consumption in buildings can be significantly reduced. Especially, using daylight in underground space interacts with the physiological need for human beings and provides relief from feeling secluded [1]. A light pipe system consists of a top collector, reflective tube and interior diffuser. As a result of their simple structure and cost-effectiveness, light pipe systems are found to be a practical application in many buildings [2]. However, only a few studies have investigated the daylight performance of light pipe systems in Korea. To properly use and develop the light pipe system, it is essential to identify the daylight and energy performance of light pipe systems with regarding to the effects of local climate conditions.

This paper presents the performance prediction method for light pipe systems used in an underground carpark regarding both daylight and energy effectiveness of the light pipe system. To apply a proper light pipe performance predictive model to the underground carpark, this paper discusses former predictive models [3,4,5] and compares the predicted daylight performance with the experimental data. The energy saving potential arising from the light pipe system was determined according to the different artificial lighting control methods (on/off control, two-step control, dimming control).

The predicted daylighting and energy performance of the light pipe showed that the light pipe can be a both a primary and secondary light source during daytime. The predicted lighting energy saving potential from the light pipe was 27% on average. Our findings proved that the light pipe installed in an underground carpark subject to Korean climate conditions can contribute both in increasing the daylight availability and the energy efficiency of the underground parking carpark.

1

S. Molteni, G. Courret, B. Paule, L. Michel, L. Scartezzini, "Design of anidolic zenithal lightguides for daylighting of underground spaces", Solar Energy, 69, 117-129, 2001. doi:10.1016/S0038-092X(01)00065-2

2

M. Paroncini, B. Calcagni, F. Corvaro, "Monitoring of a light-pipe system", Solar Energy, 81, 1180-1186, 2007. doi:10.1016/j.solener.2007.02.003

3

D. Jenkins, X. Zhang, T. Muneer, "Formulation of semi-empirical models for predicting the illuminance of light pipes", Energy Conversion and Management, 46, 13, 2288-2300, 2005. doi:10.1016/j.enconman.2004.10.018

4

G.Y. Yun, T. Hwang, J.T. Kim, "Performance prediction by a modelling of a light-pipe system used under the climate conditions of Korea", Indoor and Built Environment, 19, 137-144, 2010.

5

G.Y. Yun, H.Y. Shin, J.T. Kim, "Monitoring and evaluation of a light-pipe system used in Korea", Indoor and Built Environment, 19, 129-136, 2010.

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