Though the news is old but i found it interesting so i thought to share

Blue Jean Insulation
Environmental Engineers Replace Chemical-Laden Building Insulation with Recycled Denim
May 1, 2006 — A medical center is insulating its walls with recycled blue jeans instead of fiberglass. The new construction material is more environmentally friendly, as fiberglass contains formaldehyde, which is believed to cause asthma and allergies. The use of denim is just one of several "green" materials used at the medical center.


More details could be found
http://www.sciencedaily.com/videos/2006/0507-blue_jean_insulation.htm