Beware of Damaging Window Reflection

Posted by in The Unusual | January 25, 2012

A Prius Owner in Southern California claims that the plastic components of her car are being melted by the reflected beam of light from her neighbor’s windows.  See the article at the website for the CBS Los Angeles affiliate.

Does this sound ludicrous?  I assure you that it is not far fetched.  We have seen vinyl siding melted on a few dwellings by the heat generated from a window reflection.  That is, the neighbor’s window acted, basically, like a magnifying glass and focused the heat on a small area of the siding.  The more scientific name for this is “thermal distortion.”

The first time we encountered this years ago, we were skeptical.  But measurement of the temperature of the siding on a cold January day (20 degrees Fahrenheit) showed that the siding was being heated to temperatures over 300 degrees.  The pattern of melted siding was arc-shaped, similar to the path of the mid-day sun.  See Figure WR-1 and WR-2.

As Ripley says, “Believe it, or not.”

window reflects on siding

WR-1 Reflected sun magnified on siding.


siding melted by sun reflection

WR-2 Siding exhibits distortion from repeated excessive heat of reflected sun.


By the way, my answer to the Prius owner, “Park in a different spot.”