Fibre Glass OR Low Density Glass Fibre Iinsulation

Everything concerning the adequate application of WUFI in the USA and Canada depending on local conditions e.g. architecture, building codes, standardization, laws et cetera.
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Peter Vander Heide
WUFI ORNL Instructors
WUFI ORNL Instructors
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Fibre Glass OR Low Density Glass Fibre Iinsulation

Post by Peter Vander Heide »

I'm looking in the Generic North American Database with WUFI 4.2. I know I have run cases using both of these materials in the past, probably making a selection based on density, if I knew what the density was.

Now I'm looking at the two of them for a new problem, and I'm trying to make sense of the hygric extensions.

Fibre Glass, 1.873 lb/ft^3 has no moisture storage function, while Low Density Glass Fibre Batt Insulation, 5.494 lb/ft^3 has a sharply increasing moisture storage function at higher humidity.

Then again,
Fibre Glass, 1.873 lb/ft^3 thermal conductivity, moisture dependent increases from .02 to .35 while Low Density Glass Fibre Batt Insulation, 5.494 lb/ft^3 has a constant thermal conductivity, moisture dependent at .25.

When I run 2 cases to compare them with exterior stucco on OSB, the results are not greatly different, but I do notice that the Fibre Glass case has almost 50% more moisture in the insulation layer even though it has no moisture storage function as opposed to the Low Density which does have moisture storage function.

I know these were compiled from a composite of sources, or just from ASHRAE 1018-RP, but can anyone offer a little guidance about which would be most representative of what is being used in the US.
Regards,
Peter
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