Analysis of the experimental performance of light pipesAnalysis of the experimental performance of light pipes Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2018-03-282017enLight pipes can provide daylight and improve lighting conditions in buildings. Knowledge of their optical performance is a prerequisite for their successful integration into buildings. This article presents and analyses the experimental performance and the specific efficiency characteristics of a light pipe as integrated into an experimental test-cell. Extensive measurements are performed for eight continuous months under clear, cloudy and intermediate sky conditions. The spatial and temporal variability of the indoor illuminance is analysed using clustering techniques. It is found that there is an almost exponential relation between the average and the maximum indoor illuminance with the exterior illuminance levels. In parallel, a strong spatial inhomogeneity is observed under all sky conditions. The transmissivity or Daylight Penetration Factor of the light pipe is found to present a strong daily variation during the clear days while it was almost constant under cloudy sky condtions. A clear correlation of the light pipe's Daylight Penetration Factor is found against the solar azimuh and solar altitude especially under clear sky conditions.http://creativecommons.org/licenses/by/4.0/Energy and Buildings151242-249 Vasilakopoulou Konstantina Βασιλακοπουλου Κωνσταντινα Kolokotsa Dionysia Κολοκοτσα Διονυσια Santamouris, Matheos Kousis I. Asproulias H. Γιανναράκης Ιωάννης Κ. Giannarakis Ioannis K. Elsevier Daylight Experimental performance Light pipes