See, those low-E windows have kind of a concave shape, so they not only reflect the light out of your living room, but focus it on whatever they're facing, like a magnifying glass frying an ant. And if your windows are aimed toward a neighbor's house that happens to have vinyl siding (which over one-third of the houses on the U.S. market do), it can get more than hot enough to make it look like they sided their house with taffy.
One Minnesota couple replaced the siding on their house multiple times before figuring out what the hell was causing it to warp. And they were just one of 25 families in their neighborhood to have experienced such damage, some of whom have given up on the Sisyphean task of replacing the siding only to have it melt again.
Via ABC News
But the good news is that they no longer have to pay someone to come in and melt their vinyl.
Since more and more building codes are starting to call for the use of low-E windows, and vinyl continues to be the most popular siding choice for new homes, the siding and window industries have engaged in a blame game over who should accept responsibility for the melting houses. The Vinyl Siding Institute has contested that vinyl is made "to withstand all kinds of natural phenomena," but that the windows have artificially concentrated the sunlight to create temperatures well over 200 degrees. The window manufacturers have countered that they are in fact rubber and the vinyl manufacturers are glue.