Using data obtained in a mobile field-test facility, measured performance of clear and low-emissivity double-glazing units is presented for south-facing and north-facing orientations. The changes in U-value and shading coefficient resulting from addition of the low-e coating are found to agree with theoretical expectations for the cold spring test conditions. Accurate nighttime U-values were derived from the data and found to agree with calculations. Expected correlation between U-value and wind speed was not observed in the data; a plausible experimental reason for this is advanced.

Units: Dual