window thickness

The window thickness for any built object is the median distance between the exterior and interior surfaces of its window panes. This should be measured in a line perpendicular to the surfaces of the windows, or perpendicular to the outer surface if the angles of the two surfaces diverge.

When double glazing is used, the thickness should include all layers of glass, air, and/or empty space within a single framing system. However in the case of a double skin facade, the thicker windows of the two skins should be used for this measurement.

The frames of windows are not counted in this measurement.