[Equest-users] How detailed is necessary

[Nicholas Caton]

Generally, I have also found combining physical spaces for energy
simulation (or load sizing) a worthwhile consideration, and relatively safe
on the risk:reward scale if applied with sound reasoning*.  This is also
“safe” from a LEED rigor perspective – there is “prescribed latitude” for
the modeler to make such decisions of zoning simplification written into
Appendix G (re: language on Thermal Blocks in Table G3.1).



To voice the counter-point, based on prior experiences (outside of LEED) I
will sometimes make the deliberate choice to “overdo it” with regard to
defining spatial resolution.  A model with each and every partitioned space
defined carries with it a maximal degree of flexibility with respect to
differentiating internals loads, scheduling, system zoning & assignments,
etc.  If I can reasonably anticipate a model will be leveraged for
open-ended & rigorous comparative or calibration study which could make use
of such flexibility, and my immediate schedule allows for it, I’ll consider
going the extra mile to carry the project’s spatial resolution to the n-th
degree.  Even when that resolution isn’t ultimately leveraged everywhere in
the model, there’s something to be said for the clarity / peace-of-mind
knowing you’ve prepared for the worst.



Likewise, the decision to make your model super-detailed requires
moderation, and can be “overdone” or mis-applied contextually.  This is
particularly true for buildings that are inherently/physically large to
begin with.  Similarly, for the purposes of decision-making within the
design process (planning/schematic/DD…) it is often wiser to build an
easily-manageable simplified model (or partial model) with deliberate
intent to scrap those efforts & start over for the final product.



Hope that helps!



~Nick



* It would be tough to square rules/guidelines around advisable “space
combinations” better than has already been done in past discussions over
the one-building lists – further reading awaits in the archives!





* NICK CATON, P.E.*
*Owner*



*Caton Energy Consulting*
  1150 N. 192nd St., #4-202

  Shoreline, WA 98133
  office:  785.410.3317

www.catonenergy.com



*From:* John Aulbach [mailto:jra_sac at yahoo.com]
*Sent:* Thursday, March 05, 2015 8:32 AM
*To:* Jones, Christopher; Nicholas Caton; equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] How detailed is necessary



One thing that may have a bearing on how to zone is that, from my
understanding, the normal LEED reviewer is not necessarily an enerhy
mpdeler and will not see the 2-d or 3-d models during the review.

I am unsure how close a reviewer matches the actual HVAC units to a list
from the model. But I would have no trouble combining like zoned floors
such as a hotel or standard office.

So I will vote with Chris (and I think Nick). The fewer zones the better.

Some of you folks are spoiled on Run time. Back in 1987, running Doe-2.1b
on a 6 mz IBM AT, turn around was 12 hours.

Sent from Yahoo Mail on Android
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------------------------------

*From*:"Jones, Christopher" <cjones at halsall.com>
*Date*:Thu, Mar 5, 2015 at 7:48 AM
*Subject*:[Equest-users] How detailed is necessary

Nick’s comment brings up a question.  I am interested in others’ opinions
on “how detailed is necessary” in reference to combining spaces.  I tend to
combine spaces to reduce the number of zones in the model.  For example, I
will combine a group of interior offices with adjacent washrooms, storage
rooms, and other service spaces with exhaust only.  I know others will
define each of these spaces individually significantly increasing the
number of spaces/zones in the model.



The benefit of combining spaces is to reduce the time it takes to draw the
spaces in eQuest.  This helps to reduce the complexity of the model and the
run time.

The drawback is that you have to sum the lighting, process loads, and HVAC
inputs, etc.  I use pivot tables to do the summing for me.



Any thoughts appreciated.



*Christopher Jones**,* P.Eng.
Tel: 416.644.4226 • Toll Free: 1.888.425.7255 x 527



*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
<equest-users-bounces at lists.onebuilding.org>] *On Behalf Of *Nicholas Caton
*Sent:* Thursday, March 05, 2015 1:48 AM
*To:* Anura Perera; equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Modelling thermal zone with multiple AHUs



Hi Anura,



If the individual systems do not act independently, or otherwise are not
expected to handle substantially different load profiles through the year
(consider beyond internal loads: do some zones have differing skin loads?),
then it’s probably safe to combine systems.



In my experience, I would however caution this particular approach of
combining systems to streamline your model development has potential to
backfire.  The time you save in the short term with inputs could be lost to
processing those system inputs (creating & documenting those
heating/cooling/airflow capacity sums and weighting associated unitary
efficiencies) and perhaps also in troubleshooting/re-constructing the model
if you find out later the assumption of identical system behavior was
off-base.  On the other hand, the extra time you would spend setting up
each individual system could be better invested elsewhere in the modeling
process to create a better final product (or towards getting home on time)!



In my mind, this sort of “how detailed is necessary” decision is a matter
of risk:reward.  It’s a regular category of judgments that pop up all the
time in new work.  Being able to recognize and explore opportunities for
acceptable approximations is a defining trait for experienced modelers.



Insofar as LEED reviewers are concerned, I have anecdotally combined
systems (documenting them as such with supplemental language) without
incident in past projects.



Kind regards,



~Nick



*NICK CATON, P.E.*
*Owner*



*Caton Energy Consulting*
  1150 N. 192nd St., #4-202

  Shoreline, WA 98133
  office:  785.410.3317

www.catonenergy.com



*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
<javascript:return>] *On Behalf Of *Anura Perera
*Sent:* Wednesday, March 04, 2015 4:01 PM
*To:* equest-users at lists.onebuilding.org <javascript:return>
*Subject:* [Equest-users] Modelling thermal zone with multiple AHUs



Dear All,



I am modelling a building having thermal blocks with multiple thermal
zones. Each thermal zone has an AHU. The floor level internal loads are
evenly distributed. As such I am planning to model the thermal block
considering all AHUs in the thermal block as lumped into one large AHU with
total capacity of all individual AHUs of zones in the block.



Will this be an acceptable approach for LEED reviewers?



Any experience to share please?



Thanks in advance

Anura


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