To determine the performance of fenestration systems under irradiation-exposed conditions, the Solar Calorimetry Laboratory has developed a unique, solar-simulator-based test method. With this method, performance curves are determined for test specimens over a range of climatic conditions, allowing thermal characteristics i.e., the shading coefficient and the U-value, to be determined. These characteristics are representative of the total fenestration system, including edge of glazing, sash, and frame effects on thermal performance. Test results obtained with this method are presented for six windows, and an uncertainty analysis is detailed.

KEYWORDS: windows, thermal resistance, heat flow, calculating, measuring, openings, window frames, laboratory testing.