Saw this on JLC…very interesting phenomena;

Low-E Windows Blamed for Melted Vinyl Siding

Last winter, when Urbandale, Iowa, builder Mark Parlee was asked to investigate a case of thermally distorted vinyl siding, he was surprised at what he found: A trio of small windows located high on the south-facing wall of a neighboring home was reflecting sunlight onto the north-facing wall of the affected home, creating three focused hot spots — each about 6 inches square — that moved diagonally across the siding in the opposite direction of the sun (see photos). Parlee measured temperatures on the surface of the siding in excess of 200°F at one of these spots, even though the air temperature was only 10°F that day.

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