[BLDG-SIM] Modeling Thermal Mass in eQUEST

[Jeff Haberl]

FYI...

 

This would be really tricky...in EQUEST, as in DOE-2, one would need to
make sure the CWFs are turned on, and all walls, roofs, etc. are
layered. In addition, one would need proper framing-factors for the
walls, and if the building is slab on grade, effective u-values
following Winklemann's method. One would need to look at the BDL to
ascertain this.

 

Then comes the fun part...since a simulation like DOE-2 or EQUEST might
not really be simulating what is going on, one need to have "effective
parameters" for the coupling of the thermal mass to the interior node,
etc. 

 

For example, see the paper by Janet Manke and Doug Hittle in the 1985
ASME Conference proceedings that used "effective" parameters to best
represent the thermal mass, convection and radiation exchange within a
building. There are other papers that have addressed this issue using
TRNSYS by Jim Braun, et al. in the ASHRAE literature. I believe there
was also an ASHRAE Research Project on this as well.

 

Beware....

 

Jeff

 

8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  8=()  8=)  8=|  8=)  :=')  8=)
8=)  8=?

Jeff S. Haberl, Ph.D.,P.E.............................jhaberl at tamu.edu
<mailto:P.E...........................................jhaberl at 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, 77843..........URL: www-esl.tamu.edu

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

 

________________________________

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Ryan
Hammond
Sent: Tuesday, July 10, 2007 3:16 PM
To: BLDG-SIM at gard.com
Cc: Nathan Fleischer; Mauro Small
Subject: [BLDG-SIM] Modeling Thermal Mass in eQUEST

 

All,

 

We're trying to model thermal mass effects on load shifting for a
non-residential building for the Savings By Design program.

 

Title-24 references tables for thermal mass savings for low-rise
residential depending on the constructions present.  From my
understanding, EnergyPro follows the ways of the T-24 energy code, and
really doesn't model thermal mass for what it is.  

 

I know eQUEST requires the "Layers Input" for the program to assign a
mass to the construction (and not the "U-Value Input").  

 

Does eQUEST also reference tables (similar to the T-24 energy code), or
are there some genuine calculations made?

 

Thanks again,

R. Ryan Hammond, LEED(r) AP

Designer

 

G U T T M A N N & B L A E V O E T 

C o n s u l t i n g  E n g i n e e r s

 

 

 
 
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