WHAT IS FIBERGLASS INSULATION?

The purpose of insulation is to slow down the movement of heat through your walls. The insulation doesn't care which way the heat is moving, so it does just as good a job keeping the summer heat out as it does the winter heat in.

If you just leave a gap between the inner and out walls of your house, the only way to transfer heat is through convective air currents. (Well, heat will also be conducted through the wall studs, but for our purposes we can ignore them.) This is better than a thin, solid wall, but it's still not good enough under most conditions.

The problem is that the moving air has a direct path from the warm outside wall to the cool inside wall. It would help things a lot to find a way to slow down the air currents.

This is where fiberglass insulation comes in handy. Fiberglass insulation is made from very fine strands of glass held together in a thick, random mat. Between the fibers are many small pockets of air.

The glass strands themselves are very poor conductors of heat. In order for heat to be transfered through the mat, then, it must be carried convectively through the tiny air pockets. But the randomness of the strands means there is no direct path through the mat, so the heated air must take a very circuitous route through the wall.

The insulating properties of fiberglass mat depend on this random path. If the mat is compressed, the path becomes shorter, and the heat gets through quicker. That is why you should not tightly pack insulation. (Extracted from about.com)

R-Pro is pleased to offer three top manufacturers of fiberglass insulation: Owen Corning - GreenGuard™ Indoor Air Quality Certified, John Manville - Formaldehyde Free ComfortTherm®
and Knauf's Batt and Blanket Insulation.