Advanced research feature: Blower off delay/latent degradation model by shorowit · Pull Request #2182 · NatLabRockies/OpenStudio-HPXML

shorowit · 2026-03-24T23:55:30Z

Pull Request Description

Adds EMS program for blower off delay/latent degradation model, as described in Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions.

TODO:

Checklist

Not all may apply:

Schematron validator (EPvalidator.sch) has been updated
Sample files have been added/updated (openstudio tasks.rb update_hpxmls)
Tests have been added/updated (e.g., HPXMLtoOpenStudio/tests/test*.rb and/or workflow/tests/test*.rb)
Documentation has been updated
Changelog has been updated
openstudio tasks.rb update_measures has been run
No unexpected changes to simulation results of sample files

bpark1327

@shorowit I went through Jon’s code and the EMS program and spotted a few differences, so I wanted to document them.
Jon's code: energyplus.py

HPXMLtoOpenStudio/resources/hvac.rb

…HPXML into blower_off_delay # Conflicts: # BuildResidentialHPXML/measure.xml # HPXMLtoOpenStudio/measure.xml

…irflow rate.

jonwinkler · 2026-03-30T16:17:48Z

The implementation (and the original implementation) has lot of equations/assumptions but very few comments. Would it be helpful for me to consult the original reference and add comments to the code so we have a better understanding for where these calculations/assumptions originate from?

docs/source/workflow_inputs.rst

…ased on the Shirey et al report.

…HPXML into blower_off_delay # Conflicts: # BuildResidentialHPXML/measure.xml # HPXMLtoOpenStudio/measure.xml

shorowit

Some walk-thru comments.

shorowit · 2026-04-13T14:56:54Z

BuildResidentialHPXML/resources/options/advanced_feature.tsv

+"Latent Degradation Model w/ Blower-Off Delay, 0 sec"			0			
+"Latent Degradation Model w/ Blower-Off Delay, 45 sec"			45			
+"Latent Degradation Model w/ Blower-Off Delay, 90 sec"			90			


Added three "advanced feature" options for the BuildResidentialHPXML measure.

shorowit · 2026-04-13T14:57:24Z

docs/source/workflow_inputs.rst

+  ``LatentDegradationModel/Enabled``             boolean                              No        false     Whether to use the latent degradation model [#]_
+  ``LatentDegradationModel/HVACBlowerOffDelay``  double    sec      >= 0              No        See [#]_  HVAC blower-off delay when using the latent degradation model


New inputs.

shorowit · 2026-04-13T14:59:21Z

HPXMLtoOpenStudio/resources/airflow.rb

      name: Constants::ObjectTypeWholeHouseFan,
      end_use: Constants::ObjectTypeWholeHouseFan,
      space: conditioned_space, # no heat gain, so assign the equipment to an arbitrary space
-      design_level: nil, # will be EMS-actuated


Just some unrelated cleanup throughout to avoid having to pass a bunch of nil values to Model.add_electric_equipment and Model.add_other_equipment.

shorowit · 2026-04-13T14:59:53Z

HPXMLtoOpenStudio/resources/battery.rb

      name: Constants::ObjectTypeBatteryLossesAdjustment,
      end_use: Constants::ObjectTypeBatteryLossesAdjustment,
      space: space,
-      design_level: 0.01,


This object is EMS-actuated, so it's confusing to specify a design level (that won't be used).

shorowit · 2026-04-13T15:01:28Z

HPXMLtoOpenStudio/resources/hvac.rb

-  RatedCFMPerTon = 400.0 # cfm/ton of rated capacity, RESNET HERS Addendum 82
+  RatedCFMPerTonDX = 400.0 # cfm/ton of rated capacity, airflow rate assumed during rating test for AC/HP systems, RESNET HERS Addendum 82
+  ActualCFMPerTonDX = 360.0 # cfm/ton of rated capacity, default actual airflow rate for AC/HP systems, RESNET
+  ActualCFMPerTonHeat = 240.0 # cfm/ton of rated capacity, default actual airflow rate for furnaces, RESNET


Clarifying that the rated cfm/ton value is for DX systems, and moved our actual cfm/ton values from hvac_sizing.rb to here so we can see everything together.

shorowit · 2026-04-13T15:01:57Z

HPXMLtoOpenStudio/resources/hvac.rb

    )
  end

+  # Adds an EMS program to model latent degradation. The model includes latent degradation during


The new EMS program.

shorowit · 2026-04-13T15:08:26Z

HPXMLtoOpenStudio/resources/output.rb

          Constants::ObjectTypeDSEHeatingHeatPumpBackupFanPump => EUT::HeatingHeatPumpBackupFanPump,
          Constants::ObjectTypeDSECooling => EUT::Cooling,
          Constants::ObjectTypeDSECoolingFanPump => EUT::CoolingFanPump,
+          Constants::ObjectTypeBlowerOffDelayFanPower => EUT::CoolingFanPump,


Assign the extra blower fan power to the Cooling Fans/Pumps end use.

Though it makes me wonder about heating. It appears that the EMS program only models extra blower fan power related to cooling. @jonwinkler, why is that?

@shorowit, This model is for only for cooling. I think heat pumps use a similar strategy in heating mode, but this model does not account for that.

Thanks, I figured that was going to be your answer. That's fine since our blower-off delay input is within the latent degradation model (SimulationControl/AdvancedResearchFeatures/LatentDegradationModel/HVACBlowerOffDelay), but I should probably clarify this point so a user is not surprised.

shorowit · 2026-04-13T15:13:45Z

workflow/tests/base_results/results_simulations_bills.csv

-base-bldgtype-mf-unit-shared-boiler-chiller-fan-coil-ducted.xml,1334.72,144.0,1037.22,0.0,1181.22,144.0,9.5,153.5,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
-base-bldgtype-mf-unit-shared-boiler-chiller-fan-coil.xml,1315.2,144.0,1018.8,0.0,1162.8,144.0,8.4,152.4,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
+base-bldgtype-mf-unit-shared-boiler-chiller-fan-coil-ducted.xml,1334.82,144.0,1037.26,0.0,1181.26,144.0,9.56,153.56,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
+base-bldgtype-mf-unit-shared-boiler-chiller-fan-coil.xml,1315.21,144.0,1018.82,0.0,1162.82,144.0,8.39,152.39,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,


I made a small change to the airflow rate assumptions for fan coils (in hvac.rb), so these results are changing very slightly.

shorowit · 2026-04-13T15:15:36Z

workflow/hpxml_inputs.json

+  "sample_files/base-appliances-dehumidifier-mechvent.xml": {
+    "parent_hpxml": "sample_files/base-appliances-dehumidifier.xml",
+    "location_epw_path": "USA_TX_Houston-Bush.Intercontinental.AP.722430_TMY3.epw",
+    "ventilation_mechanical": "Supply Only"


Added a new sample file that is in Houston (more humid than Dallas) and has supply-only mechanical ventilation, so it shows a higher dehumidification load that we can test the latent degradation model on top of.

Initial cut at adding blower off delay/latent degradation model.

251b294

shorowit self-assigned this Mar 24, 2026

shorowit added the enhancement New feature or request label Mar 24, 2026

github-project-automation bot added this to OpenStudio-HPXML Mar 24, 2026

github-project-automation bot moved this to Triage in OpenStudio-HPXML Mar 24, 2026

shorowit moved this from Triage to In progress in OpenStudio-HPXML Mar 24, 2026

shorowit and others added 4 commits March 25, 2026 13:42

Fix CI (whole SFA/MF buildings)

2562fa3

Remove continuous fan mode.

f52fc86

Incorporate unit multiplier

b18f26f

Latest results.

07f7d6b

bpark1327 reviewed Mar 26, 2026

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shorowit added 2 commits March 26, 2026 15:33

Fix copy/paste issue [ci skip]

176428e

Replace 400 with RatedCFMPerTon [ci skip]

496c8db

shorowit commented Mar 26, 2026

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shorowit and others added 3 commits March 26, 2026 16:31

Merge branch 'master' of https://github.com/NatLabRockies/OpenStudio-…

aafa292

…HPXML into blower_off_delay # Conflicts: # BuildResidentialHPXML/measure.xml # HPXMLtoOpenStudio/measure.xml

Move actual cfm/ton values to HVAC constants. Small fix to fan coil a…

f5de21c

…irflow rate.

Latest results.

8949e55

shorowit and others added 2 commits March 30, 2026 16:58

Add mech vent to our dehumidifier files and move them to Houston.

24da7fd

Latest results.

2029d99

shorowit commented Mar 31, 2026

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shorowit and others added 3 commits April 1, 2026 09:38

Refactor inputs, update docs and sample files.

11a6fda

Bugfixes, cleanup.

1cda58c

Latest results.

3e263f6

shorowit marked this pull request as ready for review April 3, 2026 21:21

jonwinkler and others added 3 commits April 7, 2026 15:05

Added comments to the blower off delay program to clarify equations b…

261b054

…ased on the Shirey et al report.

Merge branch 'master' of https://github.com/NatLabRockies/OpenStudio-…

9fe269c

…HPXML into blower_off_delay # Conflicts: # BuildResidentialHPXML/measure.xml # HPXMLtoOpenStudio/measure.xml

Update Changelog.md

954ed06

shorowit commented Apr 13, 2026

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shorowit requested a review from jonwinkler April 13, 2026 15:17

shorowit requested a review from bpark1327 April 13, 2026 15:17

Clean up documentation; clarify it applies to cooling. [ci skip]

9886e70

		``LatentDegradationModel/Enabled`` boolean No false Whether to use the latent degradation model [#]_
		``LatentDegradationModel/HVACBlowerOffDelay`` double sec >= 0 No See [#]_ HVAC blower-off delay when using the latent degradation model

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shorowit commented Mar 24, 2026 •

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