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ResStock 2024.2 Customization: ccASHP Performance, Multi-Speed Coils, and Hourly Outputs

asked 2025-01-22 09:06:16 -0600

Yapan's avatar

updated 2025-01-22 09:06:54 -0600

Hello,

I’m impressed by the recently released ResStock 2024.2 datasets and would love some guidance on customizing and running individual models within ResStock. In particular, I’m looking to:

  1. Modify cold-climate air-source heat pump performance data using the NEEP Database.
  2. Assign a multi-speed (4-speed) configuration to the ccASHP heating coil.
  3. Generate hourly time-series results.

Any advice, best practices, or insights would be greatly appreciated. Thank you!

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answered 2025-01-22 11:22:07 -0600

This is a surprisingly complicated and thorny topic. Here are a few considerations:

  1. Watch this Youtube video on HP performance, particularly the part where @Neal Kruis mentions how much bad data there is in the NEEP database. They are working to fix it, but I don't know what the current status is.

  2. Review the proposed RESNET Addendum that is meant to standardize best practices on how to model these systems. However, note that it is not final and we have already provided some feedback that is resulting in changes for the next draft.

  3. It's surprisingly tricky to get the EnergyPlus model right if you plan to use the Table:Lookup object to define the NEEP datapoints. There is a lot of rope to hang yourself with, you need to be very careful and triple-check the EnergyPlus results. See my description here for some context on one such issue.

  4. Getting the details right about backup/supplemental heating, crankcase heating, pan heaters, etc., can swing the results substantially.

  5. OpenStudio-HPXML, and therefore all products that sit on top of it (like ResStock), currently allows NEEP-based ccASHP inputs to be directly specified and ensures the EnergyPlus model is appropriately configured. It's in the process of a being updated based on the RESNET Addendum. Another reference is the resdx python library.

Hopefully someday this will all be easier. For example, some people hope that ASHRAE Standard 205 will ultimately provide detailed, model-specific data to drive the energy simulation without the need for substantial assumptions or data extrapolation.

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@shorowit Thank you so much, Scott. Those are very helpful. Could you comment on a few questions below?

I see OpenStudio-HPXML can directly convert ccASHP "PerformanceDataPoint" to a set of performance curves in IDF. If I want to change the heat pump model, can I just modify the " PerformanceDataPoint" values and let the HPXML handle the conversion?

Yapan's avatar Yapan  ( 2025-01-27 09:57:40 -0600 )edit

@shorowit I would like to study the temperature curves under pre-heat strategy. Such as 15:00-17:00 pre-heat (72F), 17:00-19:00 ride-through (68F), and the rest (70F). Do you have any reference papers or reports for the value of zone temperature capacitance?

Thank you so much! I appreciate your help a lot!

Yapan's avatar Yapan  ( 2025-01-27 09:57:59 -0600 )edit
1

Since the temperature capacitance multiplier is a different thing, can you ask a separate question for it? I do have a set of papers I can provide.

shorowit's avatar shorowit  ( 2025-02-06 16:42:35 -0600 )edit
1

And yes, you can just modify the PerformanceDataPoint values in the HPXML and re-run it.

shorowit's avatar shorowit  ( 2025-02-06 16:43:41 -0600 )edit

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Asked: 2025-01-22 09:06:16 -0600

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Last updated: Jan 22