There is a problem with loose-fill
fiberglass attic insulation in cold
climates. It appears that, as attic
temperature drops below a certain
point, air begins to circulate into
and within the insulation, forming
"convective loops" that increase
heat loss and decrease the effective
R-value. At very cold temperatures
(-20°F), the R-value may decrease
by up to 50%.
The problem was first documented
twelve years ago at the
University of Saskatoon in
Saskatchewan. Using infrared
thermography, researchers
observed hexagonal cold patterns
on the ceiling of a house insulated
with cubed loose-fill fiberglass.
They suspected that the cold
spots were caused by air circulation
within the insulation.
In 1982, researchers at the
Owens-Corning Fiberglas Research
Station in Granville, Ohio,
observed a measurable decrease in
R-value when a full-scale