01358nas 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<p>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.</p>1 aRubin, Michael, D.1 aPowles, Rebecca  uhttps://facades.lbl.gov/publications/optical-properties-glazing-materials