[BLDG-SIM] Zoning Granularity in Modeling

[David S Eldridge]

I remember an example from my BLAST support days in the BLAST User's
Manual where there was an example for a simple building at Fort
Monmouth, NJ showing the difference between a one-zone and seven-zone
model.  (I think the annual difference was 5% to 7%?)

I agree with "the Paul's" that there are definitely going to be a large
number of projects where you've got to put in some detailed zoning to
realistically model the building.  For some system types such as for a
water-loop heat pump system (or City Multi when that is available!), one
of the premises may be that energy can be transferred from zones that
need cooling to zones that need heating.  Obviously you won't capture
this effect unless these areas are separate zones.

So the issue of "granularity" is going to depend a lot on the system
type and building usage.  If the granularity "test" is applied to an
office building where the operation is homogeneous and all of the zones
have the same internal gains and same schedules, then maybe you get 2%
to 10% difference or less between a single-zone model and a hundred zone
model.  For the more complicated building or zoning dependent system, it
may be much more.

As for a research project to study this...it will be limited in
usefulness depending on the number of variables that you can account for
in the buildings to be modeled.  I sense much extrapolation and less
interpolation.  Unless you are Wal-Mart or a spec office developer.

David

 

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Paul
Erickson
Sent: Thursday, August 23, 2007 11:41 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Zoning Granularity in Modeling

 

I agree with Paul's statement that the extent of zoning often falls
between the two scenarios previously mentioned.  My experience modeling
complex buildings has shown that more extensive zoning is often
required, especially if we desire to produce more "honest" and "useful"
results.  Paul suggests studying the issue of granularity.  Is anyone
aware of work that has been done on this topic?  Has anyone made a
comparison of three zoning approaches for the same building (i.e. coarse
granularity in the SD phase modeling; coarse granularity in the detailed
phase modeling; and fine/medium granularity in the detailed phase
modeling)?  What sort of results are seen?  

 

With LEED, EPACT, and code-compliance modeling on the rise, it seems
that the energy modeling community would want to affirm or reaffirm the
approach to zoning granularity that would best provide a balance of
credibility (usefulness), consistency (i.e. % savings) and value
(time/budget), seeing as many clients in the marketplace are skeptical
of energy modeling.  

 

Paul Erickson

Affiliated Engineers, Inc.

 

 

>>> "Paul Riemer" <PaulR at TWGI.com> 8/23/2007 10:45 am >>>
Thank you Kevin & Jeff for showing everyone the extreme range of
modeling approaches in our profession.  I happen to think the answer is
somewhere in the middle for most buildings types and analysis goals.  

Given the rise of LEED & EPACT, our industry needs more published best
practices addressing things like zoning granularity but before we can
write those we probably need to study them. 

Would anyone like to work together to find money and/or time to study
how sensitive energy and savings predictions are to zoning granularity
or other basic modeling practices?

Paul Riemer
THE WEIDT GROUP


-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Jeff
Haberl
Sent: Wednesday, August 22, 2007 1:56 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] max number of tracked modifications exceeded

Why do you need so many zones? Five per floor is the usual, two can also
suffice. 

Jeff
BB 8=!  8=)  :=)  8=)  ;=)  8=)  8=(  8=)  :=')  8=)  8=)  8=? BB

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

BB 8=/  8=)  :=)  8=)  ;=)  8=)  8=()  8=) 8=?  8=)  8=)  8= BB


----- Original Message -----
From: BLDG-SIM at gard.com <BLDG-SIM at gard.com>
To: BLDG-SIM at gard.com <BLDG-SIM at gard.com>
Sent: Wed Aug 22 12:29:23 2007
Subject: [BLDG-SIM] max number of tracked modifications exceeded

Ok, this could be embarrassing, but I got to know.



Could anyone shed some light on this error message I keep getting?  As
it turns out, I ended up with 405 zones.  I heard Doe-2.1 was limited to
99zones, is there a new limit for Doe 2.2. 



I was under the assumption that when modeling for LEED certification
each space in the architectural design should be modeled as a separate
space for building simulation, is this thought right or completely
wrong?  Thanks for the help.



Kevin


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