Architects Newspaper recently shared some surprising news suggesting that new low-E windows could be responsible for melting the vinyl siding on neighboring homes. Reflections from the windows are reported to be heating up nearby vinyl siding to the point that it melts.
Reflective building materials can have detrimental effects on neighboring structures. The Disney Concert Hall in LA designed by Frank Gehry was perhaps the most notorious case of reflectivity from a building causing local overheating. (The polished metal cladding was lightly sandblasted shortly after the building was completed in order to correct the problem.)
The test report from Infrared New England about vinyl siding melting strongly implies that it is low-E windows that are causing the problem. However, a flat window shouldn’t be able to reflect more sunlight than the amount that falls on it, which should be similar to the amount that falls on a similar area of siding — the siding should be no more susceptible to melting than it is when it is normally exposed to the sun. A local television station reporting on the story notes that it is the inward flexing and curvature of the windows that is concentrating the sun and causing problems. The low-E coating is immaterial, aside from the fact that many replacement windows have low-E coatings, and the problems may crop up when replacement windows are installed.
There are many green reasons to prefer other kinds of exterior cladding over vinyl siding. We aren’t aware of this as a widespread problem across the country, and neither vinyl siding nor low-E windows are particularly new technologies. But from what we see, it’s highly unlikely that anything about the windows being low-E is responsible for problems that may be occurring.