[Bldg-sim] Trace 700 vs 3D+ for load calculations

Mon Feb 28 13:29:43 PST 2022

One interesting question would be to know whether anyone has done rigorous
analysis on whether buildings constructed using RTS calculations are
oversized and by how much.

I expect this would be a really useful exercise in growing your confidence
in the suitability of new calculations.

On Mon, Feb 28, 2022 at 9:03 PM Paul Riemer via Bldg-sim <
bldg-sim at lists.onebuilding.org> wrote:

> Hi Curtis and list
>
> Over the last 20+ years we have done most of our loads in Trace 700 and
> are aware of the need to migrate.  We answered a survey that implied Trane
> was considering modifying the sunset timeline but we have not read or heard
> anything lately.  We have started a modest comparison and are trying to be
> systematic and a bit rigorous about it.  In our study, internal loads and
> low mass wall/roof/window conductivity have seemed reasonably comparable.
> We are looking more at infiltration, solar gains, and ground coupled heat
> transfer.  We have not gotten to testing high mass scenarios. Yes the
> differences have us wondering if we 1) trust that 3D is more accurate and
> we keep our standard safety factors OR 2) devise workarounds and/or
> different safety factors OR 3) find another software package.  We have not
> used 3D output for a live project and we have not communicated with Trane
> about this.  I would be open to a conversation next week or later.
>
> Thanks,
>
>
>
>
>
> *Paul Riemer*, PE, LEED AP BD+C
> Senior Associate | Mechanical
> D: 612-465-7696 | C: 612-220-2301
>
> 50 South Sixth Street \ Suite 1100
> Minneapolis Minnesota 55402
>
> *DUNHAM*
>
> *From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On
> Behalf Of *Curtis Fong via Bldg-sim
> *Sent:* Monday, February 28, 2022 12:12 PM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Trace 700 vs 3D+ for load calculations
>
>
>
> Hello Trace users!
>
>
>
> As you probably know, Trane is phasing out Trace 700. This is the last
> year that you can renew your annual license, and after your license expires
> sometime in 2023, there will be very limited opportunity to edit and run
> existing models. The replacement is the heavily hyped Trace 3D+, which uses
> EnergyPlus as the simulation engine. From a load calculation perspective,
> this is a very big deal. Trace 700 is one of the industry’s leading load
> calculation tools and is arguably the basis for the standard of care for
> HVAC equipment sizing. Load calculations in E+ are based on the heat
> balance method, which is a fundamentally different approach from the
> radiant time series that is commonly used for cooling loads in Trace 700.
> Having a 3D view in the tool is, for sure, a step forward and the heat
> balance method is a more rigorous approach, but applying that to real
> equipment sizing is not trivial. The workflow will be different and the
> load results will also be different, generally lower in 3D+. The load calc
> results with the 3D+ approach will be sensitive to some inputs that are not
> particularly critical in Trace 700 so care will be required as designers
> switch over to this new tool. But yet Trane has provided very little
> guidance on the differences between the software tools, calculation
> methods, and resulting peak loads. Really only this:
> https://tranecds.custhelp.com/app/answers/detail/a_id/454/~/comparison-of-trace-700-and-trace-3d-plus
>
>
>
> One potential data point is to compare the published Std 140 results for
> 700 vs 3D+. Below are the peak sensible cooling results for the high mass
> building, 700 at left in pink, and 3D+ at right in pink. High mass would be
> the most challenging comparison, where there is more time delay heat
> transfer with the HB method – but *these are tremendously different peak
> loads* (3D+ predicts a ~30% lower peak for case 900). Are you ready to
> hang your PE license on that result at right? I don’t know enough about Std
> 140 to know whether this is reflective of an apples to apples comparison
> between load calculation results between the two tools but it seems to
> match my general expectation.
>
>
>
>
>
>
> https://www.trane.com/content/dam/Trane/Commercial/software/trace-3d-plus/T3DP_V3-01-25_final_lowres.pdf
>
>
> https://tranecds.custhelp.com/ci/fattach/get/266924/0/filename/STANDARD+140-2014+OUTPUT+FORM+-+Modeling+Notes.pdf
>
>
>
> So my questions:
>
> 1.       Has anyone already switched to using 3D+ for load calculations?
>
> 2.       Has anyone done a careful comparison between the two tools
> and/or developed any guidance on workflow differences that you would be
> willing to share to avoid duplicating effort? (it would obviously be better
> and more practical for Trane to do this since they are forcing the switch,
> instead of expecting their users to each do it on their own)
>
> 3.       Do you have concerns about using load calculations from 3D+ for
> equipment sizing, and have you expressed those to Trane? Perhaps if there
> was enough industry concern over the risk of under- or mis-sized equipment,
> they might consider maintaining Trace 700 to avoid having users simply
> switch to using Carrier HAP.
>
>
>
> Thanks for reading!
>
>
>
> Curtis
>
>
>
> Curtis Fong, PE
>
> Associate
>
>
>
> taylor|engineers
>
> 1080 Marina Village Parkway, Suite 501, Alameda CA 94501
>
> (510) 747-9660 direct, (510) 749-9135 office
>
> (510) 749-9136 fax, (510) 290-1368
>
>
>
> *cfong at taylorengineers.com <cfong at taylorengineers.com>*
>
> *www.taylorengineers.com <http://www.taylorengineers.com/>*
>
>
>
>
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-- 

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<http://www.sketchup.com/sefaira>
Trimble - Architecture & Design Division
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