ASSESSMENT OF DAYLIGHT TRANSMISSION VIA LIGHT-PIPES INTO INTERIOR SPACES

Abstract

One of the main directions for reducing the carbon emissions into the atmosphere consists in the use of advanced daylighting technologies capable of transmitting daylight into the depth of buildings. The possibility of using daylight throughout the day for illuminating the interiors of a building would help to significantly reduce the global energy consumption of that building and to cut down the carbon emissions. Lighting is responsible for 40-60% of the total energy consumption within commercial buildings and the use of daylight instead of electric lighting would lead to large energy savings. This paper assesses the performance of daylight transmission through light-pipes using the SUNPIPE systems installed in the Laboratory of Lighting Systems at the Faculty of Civil Engineering of Brasov. There are two light-pipes used in this study: one horizontal pipe of 300mm diameter and 3m length, collecting daylight on the facade of the building, and one vertical pipe of 300mm diameter and 1m length, collecting daylight on the roof of the building. The light-pipes are similar and use 98% reflectance pure silver base mirror-finish aluminium tubes. Illuminance values are measured inside the pipes and on the working plane for different external scenarios and an evaluation module is proposed by the use of nonlinear regressions.