Fiberglass R-value loss in cold weather - R-value drop quantified

[Daox]

I just wanted to discuss this and get some info floating around here on it. It has been mentioned a number of times here that fiberglass looses its r-value in cold weather.

Today, I found this article that actually quantifies the extreme loss of r-value as temperature drops. This article shows that fiberglass will loose up to 50% of its r-value if the temperature differential is high enough! In contrast, it shows cellulose actually raises in r-value as the temperature differential increases.

FOAM-TECH: Building Envelope Theory - R-Value Drift


Through my reading, I have heard this is mainly from air convection through the insulation. The cold air drops and warm air rises right through the insulation itself. Cellulose is apparently much better at blocking air flow through itself than fiberglass. So, I'm sure closed cell foam would be even better.

Here is another article that goes into detail a bit more.
Convective Loss in Loose-Fill Attic Insulation


The one thing that these articles don't address is batt insulation. Each article specifically addresses the fiberglass as loose fill fiberglass. Are the same problems there with batt insulation?