01745nas a2200133   4500008004100000050001400041245008400055210006900139260003400208520124400242100002201486700002401508856007901532       1992                        eng d  aLBL-3219800aA New Method for Predicting the Solar Heat Gain of Complex Fenestration Systems0 aNew Method for Predicting the Solar Heat Gain of Complex Fenestr  aClearwater Beach, FLc12/19923 a<p>A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.</p><p>The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.</p>1 aKlems, Joseph, H.1 aWarner, Jeffrey, L.  uhttps://facades.lbl.gov/publications/new-method-predicting-solar-heat-gain