[BLDG-SIM] Increased R value Credit for Concrete and Themal M assing

[Jeff Haberl]

Hello:
 
We are currently completing a report for the Texas Legislature where we have
attempted to simulate the effects of thermal mass on a "standard" building
as defined by the 2000 IECC. So far, we've spent most of our time trying to
define how to simulate the building, since the 2000 IECC is flawed in that
it requires 13.5 lb/ft2 of floor space, which makes the simulation of
thermal mass impossible with DOE-2. (i.e., it forces the use of floor-weight
values, which then use pre-calculated ASHRAE weighting factors, which are
not as accurate as custom weighting factors). 
 
There are multiple issues with accomplishing this with DOE-2, which our
report points out in some detail. In general the report shows mixed results,
with the largest variation coming from peak value predictions, which is
important for Texas and the Ozone reduction during summertime (i.e.,reduce
peak cooling loads). We also found the following items affect the results:
SC vs Window 5 simulation of windows, Effective-U value and fictitious
ground heat transfer (i.e., Winklemann's memo), placement of the mass has an
impact as well (inside or outside of thermal mass). Finally, the ground
temperatures that DOE-2 uses when using a TMY2 tape for a city are suspect
(i.e., too cold for Texas in the summer and winter, average o.k.). I'm
hoping to have a synopsis of the report to pass around at the next 90.1
Envelop meeting and/or TC 4.7 in Kansas City.
 
Jeff
 
8=!   8=)  :=)   8=)   ;=)   8=)   8=(   8=)   8=()   8=)   8=|   8=)   :=')
8=)   8=)   8=? 

Jeff S. Haberl, Ph.D., P.E.............................jhaberl at esl.tamu.edu 
Professor...............................................Office Ph:
979-845-6507 
Department of Architecture...........................Lab Ph: 979-845-6065 
Energy Systems Laboratory...........................FAX: 979-862-2457 
Texas A&M University..................................77843-3581 
College Station, Texas, USA...........................URL: www-esl.tamu.edu 

8=/   8=)  :=)   8=)  ;=)   8=)   8=()   8=)   :=)   8=)   8=!   8=)   8=?
8=)   8=)   8=0   

-----Original Message-----
From: postman at gard.com [mailto:postman at gard.com]On Behalf Of David Stewart
Sent: Tuesday, December 02, 2003 11:27 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Increased R value Credit for Concrete and Themal Massing


Dear Folks
 
Has anyone explored the increased R value credits for thermal massing for
example Dow T-Mass etc. and can one simply increase the R value to the
'effective R value while changing the mass in DOE.  I would like some more
background on this credit with 3rd party validation
 
Thanks
 
Dave Stewart
 
David C. Stewart & Associates Inc.
16 Shawinigan Road
Dartmouth, NS B2W 3A3
 
Website: http://dcsa.ca <http://dcsa.ca> 
 
Tel: 902 462 8111
Fax 902 435 6646



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