HPWH COP Adjustment in confined space

Changelog.md

@@ -13,6 +13,7 @@ __New Features__
 - Water heater improvements:
   - Improves electric water heater tank losses when using `EnergyFactor` as the metric; now consistent with how `UniformEnergyFactor` is handled.
   - Improves HPWH tank volume defaulting, particularly when `NumberofResidents` is provided.
+  - Allows HPWH performance adjustment when installed in confined space per RESNET HERS Addendum 77. When `extension/HPWHInConfinedSpaceWithoutMitigation` is "true", `extension/HPWHContainmentVolume` is used to calculate the adjustment.
 - Updated site defaults:
   - `Address/CityMunicipality`, `Address/StateCode`, `GeoLocation/Latitude`, `GeoLocation/Longitude`, and `TimeZone/UTCOffset` now default based on zip code if available.
   - `TimeZone/DSTObserved` now defaults to false if `Address/StateCode` is 'AZ' or 'HI'.

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>370efaa7-01ec-407f-92cd-2b37f15c9baa</version_id>
-  <version_modified>2025-10-31T17:24:17Z</version_modified>
+  <version_id>ebf347a8-a3b8-4096-a72c-078aa24e7d59</version_id>
+  <version_modified>2025-10-31T18:46:56Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -348,7 +348,7 @@
       <filename>defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>2157E4EC</checksum>
+      <checksum>73012C00</checksum>
     </file>
     <file>
       <filename>electric_panel.rb</filename>
@@ -384,7 +384,7 @@
       <filename>hpxml.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>DBE0703D</checksum>
+      <checksum>26FF824B</checksum>
     </file>
     <file>
       <filename>hpxml_schema/HPXML.xsd</filename>
@@ -402,7 +402,7 @@
       <filename>hpxml_schematron/EPvalidator.sch</filename>
       <filetype>sch</filetype>
       <usage_type>resource</usage_type>
-      <checksum>4BBE1448</checksum>
+      <checksum>565E6550</checksum>
     </file>
     <file>
       <filename>hpxml_schematron/iso-schematron.xsd</filename>
@@ -696,7 +696,7 @@
       <filename>waterheater.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>003609A7</checksum>
+      <checksum>D373B68C</checksum>
     </file>
     <file>
       <filename>weather.rb</filename>
@@ -732,7 +732,7 @@
       <filename>test_defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>test</usage_type>
-      <checksum>67DD734E</checksum>
+      <checksum>5C9F88DA</checksum>
     </file>
     <file>
       <filename>test_electric_panel.rb</filename>
@@ -810,7 +810,7 @@
       <filename>test_validation.rb</filename>
       <filetype>rb</filetype>
       <usage_type>test</usage_type>
-      <checksum>AC7D67C4</checksum>
+      <checksum>A339372A</checksum>
     </file>
     <file>
       <filename>test_vehicle.rb</filename>
@@ -822,7 +822,7 @@
       <filename>test_water_heater.rb</filename>
       <filetype>rb</filetype>
       <usage_type>test</usage_type>
-      <checksum>4B3C5F26</checksum>
+      <checksum>CADD169C</checksum>
     </file>
     <file>
       <filename>test_weather.rb</filename>

HPXMLtoOpenStudio/resources/defaults.rb

@@ -3347,6 +3347,11 @@ def self.apply_water_heaters(hpxml_bldg, eri_version, schedules_file)
           water_heating_system.operating_mode_isdefaulted = true
         end
 
+        if water_heating_system.hpwh_confined_space_without_mitigation.nil?
+          water_heating_system.hpwh_confined_space_without_mitigation = false
+          water_heating_system.hpwh_confined_space_without_mitigation_isdefaulted = true
+        end
+
       end
       next unless water_heating_system.location.nil?
 

HPXMLtoOpenStudio/resources/hpxml.rb

@@ -8614,32 +8614,34 @@ def from_doc(building)
 
   # Object for /HPXML/Building/BuildingDetails/Systems/WaterHeating/WaterHeatingSystem.
   class WaterHeatingSystem < BaseElement
-    ATTRS = [:id,                        # [String] SystemIdentifier/@id
-             :fuel_type,                 # [String] FuelType (HPXML::FuelTypeXXX)
-             :water_heater_type,         # [String] WaterHeaterType (HPXML::WaterHeaterTypeXXX)
-             :location,                  # [String] Location (HPXML::LocationXXX)
-             :year_installed,            # [Integer] YearInstalled
-             :is_shared_system,          # [Boolean] IsSharedSystem
-             :performance_adjustment,    # [Double] PerformanceAdjustment (frac)
-             :third_party_certification, # [String] ThirdPartyCertification
-             :tank_volume,               # [Double] TankVolume (gal)
-             :fraction_dhw_load_served,  # [Double] FractionDHWLoadServed (frac)
-             :heating_capacity,          # [Double] HeatingCapacity (Btu/hr)
-             :backup_heating_capacity,   # [Double] BackupHeatingCapacity (Btu/hr)
-             :energy_factor,             # [Double] EnergyFactor (frac)
-             :uniform_energy_factor,     # [Double] UniformEnergyFactor (frac)
-             :operating_mode,            # [String] HPWHOperatingMode (HPXML::WaterHeaterOperatingModeXXX)
-             :first_hour_rating,         # [Double] FirstHourRating (gal/hr)
-             :usage_bin,                 # [String] UsageBin (HPXML::WaterHeaterUsageBinXXX)
-             :recovery_efficiency,       # [Double] RecoveryEfficiency (frac)
-             :jacket_r_value,            # [Double] WaterHeaterInsulation/Jacket/JacketRValue (F-ft2-hr/Btu)
-             :standby_loss_units,        # [String] StandbyLoss/Units (HPXML::UnitsXXX)
-             :standby_loss_value,        # [Double] StandbyLoss/Value
-             :temperature,               # [Double] HotWaterTemperature (F)
-             :uses_desuperheater,        # [Boolean] UsesDesuperheater
-             :related_hvac_idref,        # [String] RelatedHVACSystem/@idref
-             :tank_model_type,           # [String] extension/TankModelType (HPXML::WaterHeaterTankModelTypeXXX)
-             :number_of_bedrooms_served] # [Integer] extension/NumberofBedroomsServed
+    ATTRS = [:id,                                     # [String] SystemIdentifier/@id
+             :fuel_type,                              # [String] FuelType (HPXML::FuelTypeXXX)
+             :water_heater_type,                      # [String] WaterHeaterType (HPXML::WaterHeaterTypeXXX)
+             :location,                               # [String] Location (HPXML::LocationXXX)
+             :year_installed,                         # [Integer] YearInstalled
+             :is_shared_system,                       # [Boolean] IsSharedSystem
+             :performance_adjustment,                 # [Double] PerformanceAdjustment (frac)
+             :third_party_certification,              # [String] ThirdPartyCertification
+             :tank_volume,                            # [Double] TankVolume (gal)
+             :fraction_dhw_load_served,               # [Double] FractionDHWLoadServed (frac)
+             :heating_capacity,                       # [Double] HeatingCapacity (Btu/hr)
+             :backup_heating_capacity,                # [Double] BackupHeatingCapacity (Btu/hr)
+             :energy_factor,                          # [Double] EnergyFactor (frac)
+             :uniform_energy_factor,                  # [Double] UniformEnergyFactor (frac)
+             :operating_mode,                         # [String] HPWHOperatingMode (HPXML::WaterHeaterOperatingModeXXX)
+             :first_hour_rating,                      # [Double] FirstHourRating (gal/hr)
+             :usage_bin,                              # [String] UsageBin (HPXML::WaterHeaterUsageBinXXX)
+             :recovery_efficiency,                    # [Double] RecoveryEfficiency (frac)
+             :jacket_r_value,                         # [Double] WaterHeaterInsulation/Jacket/JacketRValue (F-ft2-hr/Btu)
+             :standby_loss_units,                     # [String] StandbyLoss/Units (HPXML::UnitsXXX)
+             :standby_loss_value,                     # [Double] StandbyLoss/Value
+             :temperature,                            # [Double] HotWaterTemperature (F)
+             :uses_desuperheater,                     # [Boolean] UsesDesuperheater
+             :related_hvac_idref,                     # [String] RelatedHVACSystem/@idref
+             :tank_model_type,                        # [String] extension/TankModelType (HPXML::WaterHeaterTankModelTypeXXX)
+             :number_of_bedrooms_served,              # [Integer] extension/NumberofBedroomsServed
+             :hpwh_confined_space_without_mitigation, # [Boolean] extension/HPWHInConfinedSpaceWithoutMitigation
+             :hpwh_containment_volume]                # [Double] extension/HPWHContainmentVolume
     attr_accessor(*ATTRS)
 
     # Returns any branch circuits that the component may be attached to.
@@ -8746,10 +8748,12 @@ def to_doc(building)
         related_hvac_idref_el = XMLHelper.add_element(water_heating_system, 'RelatedHVACSystem')
         XMLHelper.add_attribute(related_hvac_idref_el, 'idref', @related_hvac_idref)
       end
-      if (not @tank_model_type.nil?) || (not @number_of_bedrooms_served.nil?)
+      if (not @tank_model_type.nil?) || (not @number_of_bedrooms_served.nil?) || (not @hpwh_confined_space_without_mitigation.nil?) || (not @hpwh_containment_volume.nil?)
         extension = XMLHelper.create_elements_as_needed(water_heating_system, ['extension'])
         XMLHelper.add_element(extension, 'TankModelType', @tank_model_type, :string, @tank_model_type_isdefaulted) unless @tank_model_type.nil?
         XMLHelper.add_element(extension, 'NumberofBedroomsServed', @number_of_bedrooms_served, :integer, @number_of_bedrooms_served_isdefaulted) unless @number_of_bedrooms_served.nil?
+        XMLHelper.add_element(extension, 'HPWHInConfinedSpaceWithoutMitigation', @hpwh_confined_space_without_mitigation, :boolean, @hpwh_confined_space_without_mitigation_isdefaulted) unless @hpwh_confined_space_without_mitigation.nil?
+        XMLHelper.add_element(extension, 'HPWHContainmentVolume', @hpwh_containment_volume, :float, @hpwh_containment_volume_isdefaulted) unless @hpwh_containment_volume.nil?
       end
     end
 
@@ -8786,6 +8790,8 @@ def from_doc(water_heating_system)
       @related_hvac_idref = HPXML::get_idref(XMLHelper.get_element(water_heating_system, 'RelatedHVACSystem'))
       @tank_model_type = XMLHelper.get_value(water_heating_system, 'extension/TankModelType', :string)
       @number_of_bedrooms_served = XMLHelper.get_value(water_heating_system, 'extension/NumberofBedroomsServed', :integer)
+      @hpwh_confined_space_without_mitigation = XMLHelper.get_value(water_heating_system, 'extension/HPWHInConfinedSpaceWithoutMitigation', :boolean)
+      @hpwh_containment_volume = XMLHelper.get_value(water_heating_system, 'extension/HPWHContainmentVolume', :float)
     end
   end
 

HPXMLtoOpenStudio/resources/hpxml_schematron/EPvalidator.sch

@@ -2571,13 +2571,25 @@
       <sch:assert role='ERROR' test='count(h:WaterHeaterInsulation/h:Jacket/h:JacketRValue) &lt;= 1'>Expected 0 or 1 element(s) for xpath: WaterHeaterInsulation/Jacket/JacketRValue</sch:assert>
       <sch:assert role='ERROR' test='count(h:HotWaterTemperature) &lt;= 1'>Expected 0 or 1 element(s) for xpath: HotWaterTemperature</sch:assert>
       <sch:assert role='ERROR' test='count(h:UsesDesuperheater) &lt;= 1'>Expected 0 or 1 element(s) for xpath: UsesDesuperheater</sch:assert> <!-- See [Desuperheater] -->
+      <sch:assert role='ERROR' test='count(h:extension/h:HPWHInConfinedSpaceWithoutMitigation) &lt;= 1'>Expected 0 or 1 element(s) for xpath: extension/HPWHInConfinedSpaceWithoutMitigation</sch:assert> <!-- See [HPWHInConfinedSpaceWithoutMitigation] -->
+      <sch:assert role='ERROR' test='h:extension/h:HPWHInConfinedSpaceWithoutMitigation[text()="true" or text()="false"] or not(h:extension/h:HPWHInConfinedSpaceWithoutMitigation)'>Expected extension/HPWHInConfinedSpaceWithoutMitigation to be 'true' or 'false'</sch:assert>
       <!-- Moved/deprecated extension/OperatingMode input; see https://github.com/NREL/OpenStudio-HPXML/pull/1289 -->
       <sch:assert role='ERROR' test='count(h:extension/h:OperatingMode) = 0'>extension/OperatingMode has been replaced by HPWHOperatingMode</sch:assert>
       <!-- Warnings -->
       <sch:report role='WARN' test='number(h:HotWaterTemperature) &lt; 110'>Hot water setpoint should typically be greater than or equal to 110 deg-F.</sch:report>
     </sch:rule>
   </sch:pattern>
 
+  <sch:pattern>
+    <sch:title>[HPWHInConfinedSpaceWithoutMitigation]</sch:title>
+    <sch:rule context='/h:HPXML/h:Building/h:BuildingDetails/h:Systems/h:WaterHeating/h:WaterHeatingSystem/h:extension[h:HPWHInConfinedSpaceWithoutMitigation="true"]'>
+      <sch:assert role='ERROR' test='count(h:HPWHContainmentVolume) = 1'>Expected 1 element(s) for xpath: HPWHContainmentVolume</sch:assert>
+      <sch:assert role='ERROR' test='number(h:HPWHContainmentVolume) &gt; 0 or not(h:HPWHContainmentVolume)'>Expected HPWHContainmentVolume to be greater than 0.</sch:assert>
+      <!-- Warnings -->
+      <sch:report role='WARN' test='number(h:HPWHContainmentVolume) &gt; 1500'>HPWHContainmentVolume should typically be less than 1500 cuft when the HPWH is in confined space.</sch:report>
+    </sch:rule>
+  </sch:pattern>
+
   <sch:pattern>
     <sch:title>[WaterHeatingSystemType=CombiIndirect]</sch:title>
     <sch:rule context='/h:HPXML/h:Building/h:BuildingDetails/h:Systems/h:WaterHeating/h:WaterHeatingSystem[h:WaterHeaterType="space-heating boiler with storage tank"]'>

HPXMLtoOpenStudio/resources/waterheater.rb

@@ -976,6 +976,22 @@ def self.apply_hpwh_dxcoil(runner, model, water_heating_system, elevation, obj_n
 
     cop = water_heating_system.additional_properties.cop
 
+    # Adjust COP based on RESNET HERS Addendum 77
+    if not water_heating_system.hpwh_containment_volume.nil?
+      if not water_heating_system.hpwh_confined_space_without_mitigation
+        if water_heating_system.hpwh_containment_volume < 1000.0
+          runner.registerWarning("HPWH COP adjustment based on HPWHContainmentVolume will not be applied to #{water_heating_system.id} because HPWHInConfinedSpaceWithoutMitigation is not 'true'.")
+        end
+      else
+        # FUTURE: apply for 120V HPWH and other system types that the correction may not be accurate for
+        if water_heating_system.hpwh_containment_volume < 450.0 && (water_heating_system.backup_heating_capacity == 0.0)
+          runner.registerWarning("Heat pump water heater: #{water_heating_system.id} has no backup electric resistance element, COP adjustment for confined space may not be accurate when the containment space volume is below 450 cubic feet.")
+        end
+        rv = [water_heating_system.hpwh_containment_volume / 1500.0, 1.0].min
+        cop = (cop - 0.92) * (1 - (1.009 * Math.exp(-5.492 * rv))) + 0.92
+      end
+    end
+
     coil = OpenStudio::Model::CoilWaterHeatingAirToWaterHeatPumpWrapped.new(model)
     coil.setName("#{obj_name} coil")
     coil.setRatedHeatingCapacity(cap)

HPXMLtoOpenStudio/tests/test_defaults.rb

@@ -3635,32 +3635,35 @@ def test_heat_pump_water_heaters
     hpxml_bldg.water_heating_systems[0].operating_mode = HPXML::WaterHeaterOperatingModeHeatPumpOnly
     hpxml_bldg.water_heating_systems[0].heating_capacity = 4000.0
     hpxml_bldg.water_heating_systems[0].backup_heating_capacity = 5000.0
+    hpxml_bldg.water_heating_systems[0].hpwh_confined_space_without_mitigation = true
+    hpxml_bldg.water_heating_systems[0].hpwh_containment_volume = 800.0
     XMLHelper.write_file(hpxml.to_doc, @tmp_hpxml_path)
     _default_hpxml, default_hpxml_bldg = _test_measure()
-    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [44.0, HPXML::WaterHeaterOperatingModeHeatPumpOnly, 4000.0, 5000.0])
+    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [44.0, HPXML::WaterHeaterOperatingModeHeatPumpOnly, 4000.0, 5000.0, true])
 
     # Test defaults
     hpxml_bldg.water_heating_systems[0].tank_volume = nil
     hpxml_bldg.water_heating_systems[0].operating_mode = nil
     hpxml_bldg.water_heating_systems[0].heating_capacity = nil
     hpxml_bldg.water_heating_systems[0].backup_heating_capacity = nil
+    hpxml_bldg.water_heating_systems[0].hpwh_confined_space_without_mitigation = nil
     XMLHelper.write_file(hpxml.to_doc, @tmp_hpxml_path)
     _default_hpxml, default_hpxml_bldg = _test_measure()
-    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [66.0, HPXML::WaterHeaterOperatingModeHybridAuto, 6366.0, 15355.0])
+    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [66.0, HPXML::WaterHeaterOperatingModeHybridAuto, 6366.0, 15355.0, false])
 
     # Test defaults w/ num occupants = 1, num bedrooms = 1
     hpxml_bldg.building_construction.number_of_bedrooms = 1
     hpxml_bldg.building_occupancy.number_of_residents = 1
     XMLHelper.write_file(hpxml.to_doc, @tmp_hpxml_path)
     _default_hpxml, default_hpxml_bldg = _test_measure()
-    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [50.0, HPXML::WaterHeaterOperatingModeHybridAuto, 6366.0, 15355.0])
+    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [50.0, HPXML::WaterHeaterOperatingModeHybridAuto, 6366.0, 15355.0, false])
 
     # Test defaults w/ num occupants = 10, num bedrooms = 1
     hpxml_bldg.building_construction.number_of_bedrooms = 1
     hpxml_bldg.building_occupancy.number_of_residents = 10
     XMLHelper.write_file(hpxml.to_doc, @tmp_hpxml_path)
     _default_hpxml, default_hpxml_bldg = _test_measure()
-    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [80.0, HPXML::WaterHeaterOperatingModeHybridAuto, 6366.0, 15355.0])
+    _test_default_heat_pump_water_heater_values(default_hpxml_bldg, [80.0, HPXML::WaterHeaterOperatingModeHybridAuto, 6366.0, 15355.0, false])
   end
 
   def test_indirect_water_heaters
@@ -6302,12 +6305,13 @@ def _test_default_heat_pump_water_heater_values(hpxml_bldg, *expected_wh_values)
     heat_pump_water_heaters = hpxml_bldg.water_heating_systems.select { |w| w.water_heater_type == HPXML::WaterHeaterTypeHeatPump }
     assert_equal(expected_wh_values.size, heat_pump_water_heaters.size)
     heat_pump_water_heaters.each_with_index do |wh_system, idx|
-      tank_volume, operating_mode, htg_cap, backup_htg_cap = expected_wh_values[idx]
+      tank_volume, operating_mode, htg_cap, backup_htg_cap, hpwh_confined_space_without_mitigation = expected_wh_values[idx]
 
       assert_equal(tank_volume, wh_system.tank_volume)
       assert_equal(operating_mode, wh_system.operating_mode)
       assert_in_epsilon(htg_cap, wh_system.heating_capacity, 0.01)
       assert_in_epsilon(backup_htg_cap, wh_system.backup_heating_capacity, 0.01)
+      assert_equal(hpwh_confined_space_without_mitigation, wh_system.hpwh_confined_space_without_mitigation)
     end
   end