We have been seeing more and more evidence of argon depletion in insulated windows. Normally windows show an "edge loss" signature or, if the seal if broken, the entire window is affected. Argon depletion shows up—about 5-10 years after the window is installed—as a thermal anomaly in the center of the window. Summer images and images taken from inside show similar patterns but different heat flow. As the argon, a small-molecule, escapes out the seal (due to gas pressure equalization), air components (larger molecules) cannot make their way back in.
The result, in larger windows, is a bowing of the two panes of glass together; on smaller units there is less give and the windows often implode. When I showed the building owner the attached image yesterday, he said "I wondered how those three windows got broken last fall!"
Window manufacturers will often replace windows still under warranty showing this kind of signature—especially with a thermal signature as evidence. My colleague, Rob Spring, and I wrote a paper on the topic if anyone would like further reading.
And, yes, there are significant problems in this building with the insulation too! We are seeing a pattern related to air leakage past fiberglass insulation and, at the top, the icicles that result from similarly caused heat loss in the roof sections.
Thermally Yours,
John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820