Insulating glass i.e IG is also known as double glazing. Double glazing generally consists of two glass. The space between two glass is from 0.63 and 0.75 inches (16 and 19 mm). Air is trapped between the two glass and forms of insulation. This double glazing ensures that there is http://jlewiss.webs.com/apps/blog/show/44809885-benefits-of-double-glazing-door-and-windows