Interpreting SIM reports - CHW plant improvements

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Once you convert to DOE-2.3, you have additional sizing options and other CHW plant improvements. For example:

* For SIZING-OPTION, you can choose the COINCIDENT (simultaneous) peak load of all attached coils, or the NON-COINCIDENT total of all peak coil loads. (Or PRIMARY based on the attached equipment capacities.)
* The SIZING-WINDOW specifies how design-days are treated.
* You can specify the design LOOP-FLOW (gpm) if already known.
* You can specify the RATED-EDB and RATED-EWB for the corresponding coil ZONE:COOLING-CAPACITY.
* You can specify a STARTUP-COOL-DT that sizes the cooling coil based on the space temperature reduction you have to achieve per hour of operation.

~Bill

William Bishop, PE, BEMP, BEAP, CEM, LEED AP
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Thanks SO MUCH to Erik, Bill, Kevin, and Joe for sharing your perspectives!

I?ve nearly worked this out now! Some recap and summary information:

* Recap: PV-A reports a total capacity of 13.909 MMBtu/h.
* I do believe now this is exactly as Erik (first) described: It?s essentially the sum of all of the service hard-input coil capacities
* Adding up all of my specified coil capacities (which I confirmed are reflected perfectly in the SV-A system reports), I total 13.808 MMBtu/h
* Looking hard for the difference, I identified that at peak conditions, the additional loads captured between the peak ?coil? vs peak ?net? load per PS-H brings the total up to 13.896 MMBtu/h
* I am not simulating any additional loop process loads or pipe losses, so I?m not sure what else might be missing to arrive at 13.909 MMBtu/h, though it does appear pump heat gets me most of the way there.
* Regardless, it appears clear that indeed PV-A is reporting non-coincident total cooling capacity owing to how loops (in doe 2.2) default to SECONDARY sizing, which is supposed to simply sum all connected coils, loop loads, etc.
* PS-H and by extension PS-D, by contrast, provide peak Coincident load sums.
* In this particular building (a large 2-story conference center with a ton of glass walls (solar gains) and a hot climate), there is huge difference between the coincident and non-coincident totals: more than a factor of 2. I?m relieved to assert the peak coincident load in this model, as these results align with real-world operations (where only one chiller of the 3 installed is generally required to handle loads through the hottest days of the summer season).

The additional options Bill has highlighted for doe 2.3 are of course a welcome advance! I anticipate we will now through the COINCIDENT/NON-COINCIDENT options be able to get a little more control in how loops are sized up for our simulation. Should be a pretty great featureset for those leveraging energy simulations to aid in ?right sizing? design and plant automation. If the outputs of the model in front of me were available to the designers of 20+ years ago, they might have invested in a plant of half the size and more constructively spent that elsewhere!

~Nick
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I?m re-submitting this thread from last week as it appears a number of folks may have missed it, based on direct responses I?ve received. Likely an email / subscription issue on my end, but sorry for anyone receiving this twice!

~Nick
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Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Energy Performance Contracting
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913 . 564 . 6361
785 . 410 . 3317
913 . 564 . 6380
nicholas.caton at se.com
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United States
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