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Re: [EnergyPlus_Support] Thermal Bridging

I recommend checking the thermal properties of any construction for reasonableness.  EnergyPlus uses some data that in imported from old DOE 2.1 wall assemblies.  The value for 6 inch fiber glass is an R-19 that does not consider the thermal bridge at metal studs.

You have 2 choices:

1> Use an average thermal property from your mathcad model ( you could also use THERM 5.0 to calculate 2D heat flow and assembly U-Values). This will give you a better load approximation. 

2> Split the wall area into center of insulation and center of stud areas and use appropriate thermal values for each area.  This will allow EnergyPlus to calculate surface temperatures at the thermal bridging and may significantly impact other calculations like moisture storage in the interior finishes.

Ned Lyon

Senior Staff Engineer
Simpson Gumpertz & Heger Inc.

41 Seyon Street
Building #1, Suite 500
Waltham, MA  02453

Phone:  781-907-9000
Fax:  781-907-9009

>>> donovan@xxxxxxx 02/06/03 02:39PM >>>

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