Daylight Performance of the Modified Double Light Pipe (MDLP) Through Experimental Analysis on a Reduced Scale Model

This paper is focused on the Modified Double Light Pipe (MDLP), an innovative daylighting system set up by the authors in the Laboratory of Technical Physics of the University “G. D’Annunzio” of Pescara (Italy). It is an evolution of the Double Light Pipe (DLP), designed by the authors to distribute natural light in two underground levels of a building and tested through an experimental activity on a reduced scale model. The MDLP has been designed by modifying the same scale model of the DLP with the goal to solve some problems related to its size and the risk of glare, thanks to its smaller encumbrance, and a light shelf applied around the external tube to prevent the occupants of the room from seeing the upper brightest portion of the device. Furthermore, the light shelf reflects light towards the ceiling spreading it more uniformly on the horizontal work-plan. The technological components of the MDLP are shown demonstrating the possibility of installing it in both new and refurbished buildings. Then, the first results of an experimental activity carried out on the model of the MDLP in winter climatic conditions are shown. Although the unfavorable values of external illuminance, the MDLP contributes to distributing natural light in the passage room both with overcast and clear sky conditions. On sunny days, direct solar radiation hits the measure positions on the corners of the room producing peak illuminance values. The illuminance uniformity is calculated according to the EN 12464-1. The results can be considered satisfactory both in terms of internal illuminance and uniformity of light distribution.