Department of Energy
Nu-Wool Outperforms Fiberglass
What does the U.S. Department of Energy say about air infiltration?
"The most common insulation, fiberglass, does not stop air leakage.
In older homes, dirty fiberglass is a telltale sign of air movement
(it simply collects dirt like a filter). Certain types of insulation,
such as dense-packed cellulose and certain foams, can be effective at
reducing air flow as well as heat flow."
