Calorimeteric measurements of the dynamic net heat flow through a complex fenestration system consisting of a buff venetian blind inside clear double-glazing are used to derive the direction-dependent beam solar heat gain coefficient (SHGC) of the fenestration. These measurements are compared with calculations according to a prepared general method for deriving complex fenestration system SHGCs from bidirectional layer optical properties and generic calorimetric properties. Previously published optical measurements of the same venetian blind and generic inward-flowing fraction measurements are used in the calculation. Satisfactory agreement has been found between the SHGC measurements and the calculation. Significant dependence on incident angle was found in the measured SHGCs. Profile angle was not found to be a useful variable in characterising the system performance. The predicted SHGC was found to be inherently dependent on two angles, although only the incident angle variations were observable under the test conditions.

KEYWORDS: year 1996, comparing, calculating, measuring, windows, double glazing, heat flow, venetian blinds, solar heat gain, optical properties, performance