[Equest-users] How detailed is necessary

Chris Baker CBaker at cci-alliance.com
Thu Mar 5 22:10:47 PST 2015

I do agree with nick on this.  But if you are for example modeling in equest with perimeter core zoning then you can't exactly allocate an entire thermal zone to one end use type.
The result by space type could end up being off by a drastic amount in the final end use reports compared to actual real world space allocation and energy usage.

This is one example where equest inputs may differ from actual design in an effort to make the energy model as accurate (and easy) as possible.

How I did it was this... Each zone gets allocated 33% for this, 10% for that based on the overall building total percentages.  That way the final end use reports cannot falter.

  Personally I think the software is limiting in this regard where you are basically forced to model in unorthodox ways to reflect design drawings and data in accordance with x, y, and z.

For example, perimeter core is one of the easiest ways to model thermal blocks.

But has anyone ever seen hvac or heating designed with perimeter core approach?  I haven't and I used to work in hvac.

But you can look at the software as making it easier in a sense.  It does work both ways.

In Energy modeling its easy to get bogged down on one item too.
And sometimes that one little item can end up doubling the amount of work.

-Chris in alaska

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On Thu, Mar 5, 2015 at 2:48 PM -0800, "Nicholas Caton" <ncaton at catonenergy.com<mailto:ncaton at catonenergy.com>> wrote:

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!


* 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!


Caton Energy Consulting
  1150 N. 192nd St., #4-202
  Shoreline, WA 98133
  office:  785.410.3317

From: John Aulbach [mailto:jra_sac at yahoo.com<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<mailto: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.

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From:"Jones, Christopher" <cjones at halsall.com<mailto: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] On Behalf Of Nicholas Caton
Sent: Thursday, March 05, 2015 1:48 AM
To: Anura Perera; equest-users at lists.onebuilding.org<mailto: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,



Caton Energy Consulting
  1150 N. 192nd St., #4-202
  Shoreline, WA 98133
  office:  785.410.3317

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Anura Perera
Sent: Wednesday, March 04, 2015 4:01 PM
To: equest-users at lists.onebuilding.org
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

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