01940nas a2200169   4500008004100000050001500041245012400056210006900180300001200249490000700261520134000268100002201608700002301630700002001653700002801673856006901701       2005                        eng d  aLBNL-5881800aBi-Directional Transmission Properties of Venetian Blinds: Experimental Assessment Compared to Ray-Tracing Calculations0 aBiDirectional Transmission Properties of Venetian Blinds Experim  a187-1980 v783 a<p>An accurate evaluation of daylight distribution through advanced fenestration systems (complex glazing, solar shading systems) requires the knowledge of their Bidirectional light Transmission (Reflection) Distribution Function BT(R)DF. An innovative equipment for the experimental assessment of these bi-directional functions has been developed, based on a digital imaging detection system. An extensive set of BTDF measurements was performed with this goniophotometer on Venetian blinds presenting curved slats with a mirror coating on the upper side. In this paper, the measured data are compared with ray-tracing results achieved with a virtual copy of the device, that was constructed with a commercial ray-tracing software. The model of the blind was created by implementing the measured reflection properties of the slats coatings in the ray-tracing calculations. These comparisons represent an original and objective validation methodology for detailed bi-directional properties for a complex system; the good agreement between the two methods, yet presenting very different parameters and assessment methodologies, places reliance both on the digital-imaging detection system and calibration, and on the potentiality of a flexible calculation method combining ray-tracing simulations with simple components measurements.</p>1 aAndersen, Marilyn1 aRubin, Michael, D.1 aPowles, Rebecca1 aScartezzini, Jean-Louis  uhttps://facades.lbl.gov/publications/bi-directional-transmission