@article {11582, title = {Bi-Directional Transmission Properties of Venetian Blinds: Experimental Assessment Compared to Ray-Tracing Calculations}, journal = {Solar Energy}, volume = {78}, number = {2}, year = {2005}, pages = {187-198}, abstract = {

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.

}, author = {Marilyn Andersen and Michael D. Rubin and Rebecca Powles and Jean-Louis Scartezzini} } @techreport {1701, title = {Optics Version 5.1.01}, year = {2002}, month = {11/2002}, institution = {Regents of the University of California}, address = {Berkeley, CA}, author = {Richard Versluis and Rebecca Powles and Michael D. Rubin} } @conference {12153, title = {Optical Properties of Glazing Materials at Normal Incidence}, booktitle = {Revista della Statzione Sperimentale del Vetro}, year = {2000}, month = {10/2000}, pages = {13-16}, address = {Paris, France}, abstract = {

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.

}, author = {Michael D. Rubin and Rebecca Powles} } @article {1974, title = {Window Optics}, journal = {Solar Energy}, volume = {62}, number = {3}, year = {1997}, pages = {149-161}, abstract = {

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.

}, author = {Michael D. Rubin and Klaus von Rottkay and Rebecca Powles} }