Merge pull request #1886 from NREL/gshp-pump-power

Update GSHP default pump power
NREL · Nov 16, 2024 · fb6983a · fb6983a
2 parents cba77dd + 853aec0
commit fb6983a
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diff --git a/Changelog.md b/Changelog.md
@@ -57,7 +57,7 @@ __Bugfixes__
 - Fixes default CFIS fan power during ventilation only mode.
 - Fixes a bug that potentially oversizes heat pumps when detailed performance capacity fractions are provided.
 - For a CFIS system with a supplemental fan, fixes supplemental fan runtime when using sub-hourly timesteps.
-- Fixes GSHP fan power in net to gross calculations.
+- Fixes GSHP rated fan/pump powers in net to gross calculations and improves default modeled pump power (W/ton).
 
 ## OpenStudio-HPXML v1.8.1
 

diff --git a/HPXMLtoOpenStudio/measure.xml b/HPXMLtoOpenStudio/measure.xml
@@ -3,8 +3,8 @@
   <schema_version>3.1</schema_version>
   <name>hpxm_lto_openstudio</name>
   <uid>b1543b30-9465-45ff-ba04-1d1f85e763bc</uid>
-  <version_id>a0e85ae2-09d7-4b4a-801e-e660762f85f4</version_id>
-  <version_modified>2024-11-15T19:42:05Z</version_modified>
+  <version_id>b20ae61b-bf29-4be9-8e25-a44b3b12c232</version_id>
+  <version_modified>2024-11-16T00:20:48Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -327,7 +327,7 @@
       <filename>defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>0329B068</checksum>
+      <checksum>BCA4AD98</checksum>
     </file>
     <file>
       <filename>energyplus.rb</filename>
@@ -387,7 +387,7 @@
       <filename>hvac.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>E186B07A</checksum>
+      <checksum>0DF759D2</checksum>
     </file>
     <file>
       <filename>hvac_sizing.rb</filename>
@@ -663,7 +663,7 @@
       <filename>test_defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>test</usage_type>
-      <checksum>1531AC7C</checksum>
+      <checksum>1004443C</checksum>
     </file>
     <file>
       <filename>test_enclosure.rb</filename>
@@ -687,7 +687,7 @@
       <filename>test_hvac.rb</filename>
       <filetype>rb</filetype>
       <usage_type>test</usage_type>
-      <checksum>DCE0B460</checksum>
+      <checksum>994A2553</checksum>
     </file>
     <file>
       <filename>test_hvac_sizing.rb</filename>

diff --git a/HPXMLtoOpenStudio/resources/defaults.rb b/HPXMLtoOpenStudio/resources/defaults.rb
@@ -5401,12 +5401,11 @@ def self.get_duct_outside_fraction(ncfl_ag)
     return f_out
   end
 
-  # Gets the default pump power for a ground-source heat pump.
+  # Gets the default pump power for a closed loop ground-source heat pump.
   #
   # @return [Double] Pump power (W/ton)
   def self.get_gshp_pump_power()
-    # ANSI/RESNET/ICC 301-2019 Section 4.4.5 (closed loop)
-    return 30.0
+    return 80.0 # Rough estimate based on a literature review of different studies/websites
   end
 
   # Gets the default Electric Auxiliary Energy (EAE) for a boiler.

diff --git a/HPXMLtoOpenStudio/resources/hvac.rb b/HPXMLtoOpenStudio/resources/hvac.rb
@@ -2022,9 +2022,10 @@ def self.set_curves_gshp(heat_pump)
 
     # Fan/pump adjustments calculations
     # Fan power to overcome the static pressure adjustment
-    rated_fan_watts_per_cfm = 0.5 * heat_pump.fan_watts_per_cfm # Calculate rated fan power by assuming the power to overcome the ductwork is approximately 50% of the total fan power (ANSI 301 says 0.2 W/cfm is the fan power associated with ductwork, but we don't know if that was a PSC or BPM fan)
+    rated_fan_watts_per_cfm = 0.5 * heat_pump.fan_watts_per_cfm # Calculate rated fan power by assuming the power to overcome the ductwork is approximately 50% of the total fan power (ANSI/RESNET/ICC 301 says 0.2 W/cfm is the fan power associated with ductwork, but we don't know if that was a PSC or BPM fan)
     power_f = rated_fan_watts_per_cfm * 400.0 / UnitConversions.convert(1.0, 'ton', 'Btu/hr') # 400 cfm/ton, result is in W per Btu/hr of capacity
-    power_p = heat_pump.pump_watts_per_ton / UnitConversions.convert(1.0, 'ton', 'Btu/hr') # result is in W per Btu/hr of capacity
+    rated_pump_watts_per_ton = 30.0 # ANSI/RESNET/ICC 301, estimated pump power required to overcome the internal resistance of the ground-water heat exchanger under AHRI test conditions for a closed loop system
+    power_p = rated_pump_watts_per_ton / UnitConversions.convert(1.0, 'ton', 'Btu/hr') # result is in W per Btu/hr of capacity
 
     cool_eir = UnitConversions.convert(((1 - UnitConversions.convert(power_f, 'Wh', 'Btu')) / heat_pump.cooling_efficiency_eer - power_f - power_p), 'Wh', 'Btu')
     heat_eir = (1 + UnitConversions.convert(power_f, 'Wh', 'Btu')) / heat_pump.heating_efficiency_cop - UnitConversions.convert(power_f + power_p, 'Wh', 'Btu')

diff --git a/HPXMLtoOpenStudio/tests/test_defaults.rb b/HPXMLtoOpenStudio/tests/test_defaults.rb
@@ -2306,7 +2306,7 @@ def test_ground_source_heat_pumps
     hpxml_bldg.heat_pumps[0].backup_heating_capacity = nil
     XMLHelper.write_file(hpxml.to_doc, @tmp_hpxml_path)
     _default_hpxml, default_hpxml_bldg = _test_measure()
-    _test_default_ground_to_air_heat_pump_values(default_hpxml_bldg.heat_pumps[0], 30.0, 0.375, nil, nil, 0, nil, nil, nil)
+    _test_default_ground_to_air_heat_pump_values(default_hpxml_bldg.heat_pumps[0], 80.0, 0.375, nil, nil, 0, nil, nil, nil)
   end
 
   def test_geothermal_loops

diff --git a/HPXMLtoOpenStudio/tests/test_hvac.rb b/HPXMLtoOpenStudio/tests/test_hvac.rb
@@ -1317,13 +1317,13 @@ def test_shared_ground_loop_ground_to_air_heat_pump
     # Check cooling coil
     assert_equal(1, model.getCoilCoolingWaterToAirHeatPumpEquationFits.size)
     clg_coil = model.getCoilCoolingWaterToAirHeatPumpEquationFits[0]
-    assert_in_epsilon(5.56, clg_coil.ratedCoolingCoefficientofPerformance, 0.01)
+    assert_in_epsilon(5.84, clg_coil.ratedCoolingCoefficientofPerformance, 0.01)
     assert_in_epsilon(clg_capacity, clg_coil.ratedTotalCoolingCapacity.get, 0.01)
 
     # Check heating coil
     assert_equal(1, model.getCoilHeatingWaterToAirHeatPumpEquationFits.size)
     htg_coil = model.getCoilHeatingWaterToAirHeatPumpEquationFits[0]
-    assert_in_epsilon(3.81, htg_coil.ratedHeatingCoefficientofPerformance, 0.01)
+    assert_in_epsilon(3.94, htg_coil.ratedHeatingCoefficientofPerformance, 0.01)
     assert_in_epsilon(htg_capacity, htg_coil.ratedHeatingCapacity.get, 0.01)
   end
 

diff --git a/docs/source/workflow_inputs.rst b/docs/source/workflow_inputs.rst
@@ -3056,7 +3056,7 @@ Each ground-to-air heat pump is entered as a ``/HPXML/Building/BuildingDetails/S
   .. [#] NumberofUnitsServed only required if IsSharedSystem is true, in which case it must be > 1.
   .. [#] AttachedToGeothermalLoop must reference a ``GeothermalLoop``.
   .. [#] If AttachedToGeothermalLoop not provided, the ground-to-air heat pump will be automatically attached to a geothermal loop that is entirely defaulted.
-  .. [#] If PumpPowerWattsPerTon not provided, defaults to 30 W/ton per `ANSI/RESNET/ICC 301-2019 <https://codes.iccsafe.org/content/RESNET3012019P1>`_ for a closed loop system.
+  .. [#] If PumpPowerWattsPerTon not provided, defaults to 80 W/ton for a closed loop system.
   .. [#] Pump power is calculated using PumpPowerWattsPerTon and the cooling capacity in tons, unless the system only provides heating, in which case the heating capacity in tons is used instead.
          Any pump power that is shared by multiple dwelling units should be included in SharedLoopWatts, *not* PumpPowerWattsPerTon, so that shared loop pump power attributed to the dwelling unit is calculated.
   .. [#] SharedLoopWatts only required if IsSharedSystem is true.

diff --git a/tasks.rb b/tasks.rb
@@ -1481,7 +1481,7 @@ def apply_hpxml_modification_sample_files(hpxml_path, hpxml)
 
     hpxml_bldg.heat_pumps.each do |heat_pump|
       if heat_pump.heat_pump_type == HPXML::HVACTypeHeatPumpGroundToAir
-        heat_pump.pump_watts_per_ton = 30.0
+        heat_pump.pump_watts_per_ton = 100.0
       end
     end
     if hpxml_file.include?('chiller') || hpxml_file.include?('cooling-tower')
@@ -1843,7 +1843,7 @@ def apply_hpxml_modification_sample_files(hpxml_path, hpxml)
                                 heating_efficiency_cop: 3.6,
                                 cooling_efficiency_eer: 16.6,
                                 cooling_shr: 0.73,
-                                pump_watts_per_ton: 30.0)
+                                pump_watts_per_ton: 100.0)
       hpxml_bldg.heat_pumps.add(id: "HeatPump#{hpxml_bldg.heat_pumps.size + 1}",
                                 heat_pump_type: HPXML::HVACTypeHeatPumpMiniSplit,
                                 heat_pump_fuel: HPXML::FuelTypeElectricity,

diff --git a/workflow/sample_files/base-dhw-desuperheater-gshp.xml b/workflow/sample_files/base-dhw-desuperheater-gshp.xml
@@ -339,7 +339,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-ground-to-air-heat-pump-backup-integrated.xml b/workflow/sample_files/base-hvac-ground-to-air-heat-pump-backup-integrated.xml
@@ -346,7 +346,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-ground-to-air-heat-pump-backup-stove.xml b/workflow/sample_files/base-hvac-ground-to-air-heat-pump-backup-stove.xml
@@ -356,7 +356,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-ground-to-air-heat-pump-cooling-only.xml b/workflow/sample_files/base-hvac-ground-to-air-heat-pump-cooling-only.xml
@@ -338,7 +338,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-ground-to-air-heat-pump-detailed-geothermal-loop.xml b/workflow/sample_files/base-hvac-ground-to-air-heat-pump-detailed-geothermal-loop.xml
@@ -347,7 +347,7 @@
               </AnnualHeatingEfficiency>
               <AttachedToGeothermalLoop idref='GeothermalLoop1'/>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
             <GeothermalLoop>

diff --git a/workflow/sample_files/base-hvac-ground-to-air-heat-pump-heating-only.xml b/workflow/sample_files/base-hvac-ground-to-air-heat-pump-heating-only.xml
@@ -338,7 +338,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-ground-to-air-heat-pump.xml b/workflow/sample_files/base-hvac-ground-to-air-heat-pump.xml
@@ -339,7 +339,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-install-quality-ground-to-air-heat-pump.xml b/workflow/sample_files/base-hvac-install-quality-ground-to-air-heat-pump.xml
@@ -342,7 +342,7 @@
                 <AirflowDefectRatio>-0.25</AirflowDefectRatio>
                 <ChargeDefectRatio>-0.25</ChargeDefectRatio>
                 <FanPowerWattsPerCFM>0.365</FanPowerWattsPerCFM>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
           </HVACPlant>

diff --git a/workflow/sample_files/base-hvac-multiple.xml b/workflow/sample_files/base-hvac-multiple.xml
@@ -514,7 +514,7 @@
                 <Value>3.6</Value>
               </AnnualHeatingEfficiency>
               <extension>
-                <PumpPowerWattsPerTon>30.0</PumpPowerWattsPerTon>
+                <PumpPowerWattsPerTon>100.0</PumpPowerWattsPerTon>
               </extension>
             </HeatPump>
             <HeatPump>