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

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.

1 aAndersen, Marilyn1 aRubin, Michael, D.1 aPowles, Rebecca1 aScartezzini, Jean-Louis uhttps://facades.lbl.gov/publications/bi-directional-transmission00433nas a2200133 4500008004100000050001500041245002600056210002400082260006700106100002200173700002000195700002300215856006100238 2002 eng d aLBNL-5214800aOptics Version 5.1.010 aOptics Version 5101 aBerkeley, CAbRegents of the University of Californiac11/20021 aVersluis, Richard1 aPowles, Rebecca1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/optics-version-510101358nas a2200145 4500008004100000050001500041245006400056210006400120260002700184300001000211520087000221100002301091700002001114856007801134 2000 eng d aLBNL-4832200aOptical Properties of Glazing Materials at Normal Incidence0 aOptical Properties of Glazing Materials at Normal Incidence aParis, Francec10/2000 a13-163 a

Measurements of spectral transmittance T and reflectance R at normal incidence continue to be the most common and accurate source of energy performance data for glazing materials. Prediction of these radiometric properties from more fundamental materials data is often confounded by the complexity and uncertainty of coating structures. Angle-dependent radiometric properties of coated glazing will probably be predicted from normal-incidence data rather than being measured at many angles. The general error level demonstrated in round-robin tests is on the order 1-2%; it is often necessary to achieve better levels of performance. Based on results obtained following the round-robin tests, it is expected that accuracy of better than 0.5% can be generally achieved. A new type of absolute standard reference is described and tested with promising results.

1 aRubin, Michael, D.1 aPowles, Rebecca uhttps://facades.lbl.gov/publications/optical-properties-glazing-materials01552nas a2200157 4500008004100000050001500041245001800056210001800074300001200092490000700104520116200111100002301273700002301296700002001319856005501339 1997 eng d aLBNL-3991100aWindow Optics0 aWindow Optics a149-1610 v623 a

Optical and radiative properties of glazing materials are primary inputs for determination of energy performance in buildings. This paper revisits the problem and reformulates the calculations to encompass a variety of solutions to practical problems in window optics. Properties of composite systems such as flexible films applied to rigid glazing and laminated glazing can be predicted from measurements on isolated components in air or other gases. Properties of a series of structures can be generated from those of a base structure. For example, the measured properties of a coated or uncoated substrate can be extended to a range of available substrate thicknesses without the need to measure each thickness. Similarly, a coating type could be transferred by calculation to any other substrate. A simple monolithic model for extrapolating from normal properties to oblique properties is shown to have sufficient accuracy for the purpose of annual energy performance calculations. A process is initiated to develop a reliable method for determination of effective indices suitable for more detailed spectral and directional optical calculations.

1 aRubin, Michael, D.1 avon Rottkay, Klaus1 aPowles, Rebecca uhttps://facades.lbl.gov/publications/window-optics