Page 38 - Green Builder April 2017 Issue

heavy counterweights in big, empty holes in the wall. As a result,
IG performs much more efficiently than old windows in u-value and
removing air infiltration opportunities around the installed window.
But there’s a huge catch. Most modern windows come with a
split warranty: one part that covers the frame, the other that covers
the glass. Even Pella’s “Lifetime Limited” warranty on its Impervia
products includes only a 20-year warranty against glass failure.
By glass failure, what window companies really mean is the seal
between the panes. Glass itself doesn’t fail, unless it breaks.
Which leads to the question: Why have we accepted this rapid
obsolescence of such a major feature in every new building? Are
there no solutions other than smashing out the glass and recycling
it? I’ll answer that question shortly.

DESTINED FOR FAILURE?
How long do the seals last? According to Wikipedia, “IG units
typically last from 10 to 25 years, with windows facing the equator
often lasting less than 12 years. IGUs typically carry a warranty for
10 to 20 years depending upon the manufacturer.” According to the
window experts at Marvin, with whom I spoke at the show, seal
technology is much better. And alternatives to aluminum have made
possible better window performance. But for the most part, glazing CREDIT: REUBEN SALTZMAN, STRUCTURE TECH
warranties haven’t budged. Seals are better yes, but still short lived.
Failure of IG happens in different ways. A gas-filled unit may over
time lose all of its argon gas, resulting in a much lower performance.
Homeowners may not even notice this failure at first, but wonder why
their heating bills have increased, or why condensation is forming End of the line. When IG fails, as it inevitably will, most windows
end up in the landfill or at best, recycled. Few are repaired.
on the living space surface of the glass during winter months. The
gap between panes isn’t insulating enough to keep the inner pane
from getting cold enough to condense indoor moisture.
In more obvious failures, the seals actually develop a leak that
allows moist air to become trapped between the sheets of glass.
This can result in foggy, frozen and streaked windows that can’t
be cleaned.
To my knowledge, no major window makers offer a “takeback”
or repair program for failed insulated glass seals that are beyond
their warranty. This is a major blind spot in the industry, and a huge
opportunity for manufacturers to improve their CO2 footprint.

HOW BIG IS THE WINDOW FAILURE FOOTPRINT?
Let’s look at the numbers. First, don’t assume that every failed
window is recycled. According to a 2015 EPA report, only 23 percent
of new glass is made with recycled content. Manufacturers produce
about 0.6 pounds of CO2 to generate a pound of glass from virgin
materials. Recycled material cuts that pollution down by about 30
percent, to about 0.4 pounds of CO2 per pound of glass.
Let’s model a standard 30-inch-wide, double-hung, insulated glass
window. Window glass 0.125 inches thick weighs 1.64 pounds per CREDIT: ALADDIN INSULATION & WINDOWS INC.
square foot. The total glass weight would equal about 25 square feet
x 1.64 pounds, or 41 pounds of glass per window. Multiply 41 x 0.4
pounds of CO2, and the glass that is recycled from each window is
adding only 16 pounds of CO2 to the environment.
Forget the fact that the frames and aluminum or poly-based
spacers may not be recycled at all. Even small homes from the 1940s Spacer types. Different IG spacers offer different levels of energy
performance, but none to date has extended the lifespan of seals
had about eight windows, and modern homes are about 80 percent beyond about 20 years.

36 GREEN BUILDER Special Awards Issue 2017 www.greenbuildermedia.com

34-38 GB 0417 Windows.indd 36 4/12/17 2:23 PM