Mathematical model for the performance of light pipes

Abstract

Owing to increasing demand for improvement in working and living conditions and for energy saving, a great deal of attention has been paid to the development of natural daylight exploitation products. One invention is the light pipe (or sun pipe) system that not only brings natural light indoors where sunlight cannot reach but also improves the internal environment without generating excessive heat. A mathematical model of the light pipe system is desirable for assessment of its performance in terms of efficiency and economy. A modified form of daylight factor, widely used in building design, has been introduced to build a sophisticated model that enables prediction of the illuminance admitted by the light pipe system under investigation. Furthermore, the present model identifies those parameters that have a significant influence on the illuminance transmitted by light pipes. One 330 mm straight-run light pipe was installed within a Scottish dwelling house, and measurements have been carried out to monito...