““Fiberglass windows are highly resistant to ultraviolet radiation, which over time can cause PVC (vinyl) to break down and disintegrate.””
Helpful Links:
http://www.efficientwindows.org/
http://www.greenpeaceusa.org/toxics/
http://myhouseisyourhouse.org
http://www.bluevinyl.org/animation.htm
http://www.fiberglassworld.com
http://www.bobvila.com
http://www.dulley.com/docs/f567.htm
http://www.consciouschoice.com/sensible/sensible1501b.html