scope:

This standard specifies a method to measure the thermal transmittance of multiple glazing with flat and parallel surfaces including cast and figured rolled glass. This standard makes possible the determination of the U values in the central area of the multiple glazing. Edge effects, due to the thermal bridge through the spacer of a sealed glazing unit or through the frame are not included. Furthermore energy transfer due to solar radiation is not taken into account. The determination of the thermal transmittance is performed for conditions which will correspond to the average situation for glazing in practice. In this way a fair comparison between different products becomes possible.