01552nas a2200157   4500008004100000050001500041245001800056210001800074300001200092490000700104520116200111100002301273700002301296700002001319856005501339       1997                        eng d  aLBNL-3991100aWindow Optics0 aWindow Optics  a149-1610 v623 a<p>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.</p>1 aRubin, Michael, D.1 avon Rottkay, Klaus1 aPowles, Rebecca  uhttps://facades.lbl.gov/publications/window-optics