[BLDG-SIM] Materials properties for simulation

Chip Barnaby cbarnaby at wrightsoft.com
Wed Nov 12 07:25:37 PST 2003


Dear all --

I am working on ASHRAE 1199-RP, "Updating the ASHRAE/ACCA Residential Loads 
Calculation Procedures and Data".

The revised method under development is based on a 24 hour design-day 
simulation using a heat balance model.

In order to fully "package" the method for end use, thermal properties 
values must be selected for a moderately inclusive set of construction 
materials.

There is often disagreement among all the common sources for materials 
properties (ASHRAE HOF tables, standard values built into simulation 
programs etc.).

For example, the specific heat of gypsum wall board is given as 1.09 
kJ/kg-K (0.26 Btu/lb-F) in ASHRAE 2001 HOF Chapter 25, Table 4 (and several 
other sources that I've found that cite ASHRAE).  There is no source given 
for this value (unless I'm missing something).  Meanwhile, the California 
Energy Commission has selected 0.837 kJ/kg-K (0.20 Btu/lb-F) as their 
standard value for compliance simulations, again without documentation.

For 1199-RP, I would like to resolve at least the glaring 
discrepancies.  Beyond that, it would help the field if we could work 
toward a set of documented consensus values for common use.

Can anyone point me to authoritative sources for info that you have found 
helpful?

Chip Barnaby


---------------------------------------------------------
Chip Barnaby                   cbarnaby at wrightsoft.com
Vice President of Research
Wrightsoft Corp.               781-862-8719 x118 voice
394 Lowell St, Suite 12        781-861-2058 fax
Lexington, MA 02420            www.wrightsoft.com
---------------------------------------------------------

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