Transparent low-emissivity coatings are commonly used to reduce the thermal conductance of windows. It is important to be able to characterize and compare the wide variety of these coatings that are now available. The property that best describes the effectiveness of a coating in suppressing radiative heat transfer is the total hemispherical emissivity. It is much simpler, however, to measure the normal emissivity. This paper shows that a correspondence exists between these two properties which applies to most types of low-emissivity composite coatings. An empirical expression for this correspondence is provided.
BT - International Communications in Heat and Mass Transfer C1 -Windows and Daylighting Group
C2 - LBL-23384 LA - eng M1 - 5 N2 -Transparent low-emissivity coatings are commonly used to reduce the thermal conductance of windows. It is important to be able to characterize and compare the wide variety of these coatings that are now available. The property that best describes the effectiveness of a coating in suppressing radiative heat transfer is the total hemispherical emissivity. It is much simpler, however, to measure the normal emissivity. This paper shows that a correspondence exists between these two properties which applies to most types of low-emissivity composite coatings. An empirical expression for this correspondence is provided.
PY - 1987 SP - 561 EP - 565 T2 - International Communications in Heat and Mass Transfer TI - A Correlation Between Normal and Hemispherical Emissivity of Low-Emittance Coatings on Glass VL - 14 ER -