01559nas a2200097   4500008004100000245006100041210006000102520119800162100002201360856007901382       1992                        eng d00aNet Energy Performance Measurements on Two Low-E Windows0 aNet Energy Performance Measurements on Two LowE Windows3 a<p>Experimental studies using the Mobile Window Thermal Test (MoWiTT) Facility were undertaken to compare the performance of low-E windows manufactured with two different technologies, sputter-coated (soft-coat) and an improved pyrolytic chemical vapor deposition (hard-coat). The two technologies produce coatings with different emissivities and solar absorptions. The tests showed that from the standpoint of winter average daily performance, the higher solar transmission of the pyrolytic coatings tends to offset their higher emissivity, making the average performance of windows with the two coatings more similar than one would predict on the basis of either property alone. The tradeoff between the two window types is both orientation and climate dependent. Differences between the two windows were within the small experimental uncertainty of the measurement for all orientations except south, where the pyrolytic coating produced a larger net heat gain. Summer tests in a west-facing orientation showed that both windows produced large solar heat gains if unshaded, and that shading with an interior white venetian blind was not a very effective way of reducing these heat gains.</p>1 aKlems, Joseph, H.  uhttps://facades.lbl.gov/publications/net-energy-performance-measurements-0