HPWH ducting

Changelog.md

@@ -18,9 +18,10 @@ __New Features__
   - Allows desuperheaters to be used with the experimental ground-source heat pump model.
 - Allows optional `UsageMultiplier` for electric vehicles described using `Vehicles`.
 - 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 HPWHs to have exhaust air ducted to the outside using `HPWHDucting/ExhaustAirTermination="outside"`.
   - 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.
+  - Improves HPWH tank volume defaulting, particularly when `NumberofResidents` is provided.
+  - Improves electric water heater tank losses when using `EnergyFactor` as the metric; now consistent with how `UniformEnergyFactor` is handled.
 - 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>68c49ecc-26b8-4b04-ae0a-99c4d11d6295</version_id>
-  <version_modified>2025-12-31T16:14:24Z</version_modified>
+  <version_id>47b79fc1-dfc8-465a-9ddd-d95275a5295c</version_id>
+  <version_modified>2026-01-06T21:09:54Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -198,7 +198,7 @@
       <filename>airflow.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>7FED4CFE</checksum>
+      <checksum>CA31A32C</checksum>
     </file>
     <file>
       <filename>battery.rb</filename>
@@ -348,7 +348,7 @@
       <filename>defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>89E488C6</checksum>
+      <checksum>0FAE1876</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>C9D22AA0</checksum>
+      <checksum>F71A6B0A</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>4F63CF69</checksum>
+      <checksum>2DB74696</checksum>
     </file>
     <file>
       <filename>hpxml_schematron/iso-schematron.xsd</filename>
@@ -474,7 +474,7 @@
       <filename>model.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>7E742AB1</checksum>
+      <checksum>632A2E7B</checksum>
     </file>
     <file>
       <filename>output.rb</filename>
@@ -654,7 +654,7 @@
       <filename>schedules.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>15A3F181</checksum>
+      <checksum>662E62CE</checksum>
     </file>
     <file>
       <filename>simcontrols.rb</filename>
@@ -696,7 +696,7 @@
       <filename>waterheater.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>FBE1CBC7</checksum>
+      <checksum>01A0FB5A</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>4756D612</checksum>
+      <checksum>F3835E37</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>C04B6DB5</checksum>
+      <checksum>79D9847A</checksum>
     </file>
     <file>
       <filename>test_vehicle.rb</filename>

HPXMLtoOpenStudio/resources/airflow.rb

@@ -2320,6 +2320,7 @@ def self.initialize_mech_vent(model, spaces, infil_program, sensors)
   def self.apply_infiltration_adjustment_to_conditioned(runner, model, spaces, hpxml_bldg, hpxml_header, infil_program, vent_fans, duct_lk_imbals, schedules_file)
     conditioned_space = spaces[HPXML::LocationConditionedSpace]
     conditioned_zone = conditioned_space.thermalZone.get
+    unit_multiplier = hpxml_bldg.building_construction.number_of_units
 
     infil_flow = Model.add_infiltration_flow_rate(
       model,
@@ -2341,6 +2342,7 @@ def self.apply_infiltration_adjustment_to_conditioned(runner, model, spaces, hpx
     bal_cfm_tot = vent_fans[:mech_balanced].map { |vent_mech| vent_mech.average_unit_flow_rate }.sum(0.0)
     erv_hrv_cfm_tot = vent_fans[:mech_erv_hrv].map { |vent_mech| vent_mech.average_unit_flow_rate }.sum(0.0)
 
+    # Handle any cooking range hood ventilation
     infil_program.addLine('Set Qrange = 0')
     cooking_range_in_cond_space = hpxml_bldg.cooking_ranges.empty? ? true : HPXML::conditioned_locations_this_unit.include?(hpxml_bldg.cooking_ranges[0].location)
     vent_fans[:kitchen].each_with_index do |vent_kitchen, index|
@@ -2353,6 +2355,7 @@ def self.apply_infiltration_adjustment_to_conditioned(runner, model, spaces, hpx
       infil_program.addLine("Set Qrange = Qrange + #{UnitConversions.convert(vent_kitchen.flow_rate * vent_kitchen.count, 'cfm', 'm^3/s').round(5)} * #{obj_sch_sensor.name}")
     end
 
+    # Handle any bathroom fan ventilation
     infil_program.addLine('Set Qbath = 0')
     vent_fans[:bath].each_with_index do |vent_bath, index|
       # Electricity impact
@@ -2363,25 +2366,40 @@ def self.apply_infiltration_adjustment_to_conditioned(runner, model, spaces, hpx
       infil_program.addLine("Set Qbath = Qbath + #{UnitConversions.convert(vent_bath.flow_rate * vent_bath.count, 'cfm', 'm^3/s').round(5)} * #{obj_sch_sensor.name}")
     end
 
+    # Handle any clothes dryer venting
     infil_program.addLine('Set Qdryer = 0')
-    clothes_dryer_in_cond_space = hpxml_bldg.clothes_dryers.empty? ? true : HPXML::conditioned_locations_this_unit.include?(hpxml_bldg.clothes_dryers[0].location)
-    vented_dryers = hpxml_bldg.clothes_dryers.select { |cd| cd.is_vented && cd.vented_flow_rate.to_f > 0 }
-    vented_dryers.each_with_index do |vented_dryer, index|
+    vented_dryers_in_cond_space = hpxml_bldg.clothes_dryers.select { |cd| cd.is_vented && cd.vented_flow_rate.to_f > 0 && HPXML::conditioned_locations_this_unit.include?(cd.location) }
+    vented_dryers_in_cond_space.each_with_index do |vented_dryer, index|
       next if hpxml_bldg.building_occupancy.number_of_residents == 0 # Operational calculation w/ zero occupants, zero out energy use
-      next unless clothes_dryer_in_cond_space
 
       # Infiltration impact
       vented_dryer_unavailable_periods = Schedule.get_unavailable_periods(runner, SchedulesFile::Columns[:ClothesDryer].name, hpxml_header.unavailable_periods)
       obj_sch_sensor, cfm_mult = apply_dryer_exhaust(model, hpxml_header, vented_dryer, schedules_file, index, vented_dryer_unavailable_periods)
       infil_program.addLine("Set Qdryer = Qdryer + #{UnitConversions.convert(vented_dryer.vented_flow_rate * cfm_mult, 'cfm', 'm^3/s').round(5)} * #{obj_sch_sensor.name}")
     end
 
+    # Handle any HPWHs
+    infil_program.addLine('Set Qhpwh = 0')
+    ducted_hpwhs_in_cond_space = hpxml_bldg.water_heating_systems.select { |wh| wh.water_heater_type == HPXML::WaterHeaterTypeHeatPump && wh.hpwh_ducting_exhaust == HPXML::LocationOutside && HPXML::conditioned_locations_this_unit.include?(wh.location) }
+    ducted_hpwhs_in_cond_space.each_with_index do |ducted_hpwh, i|
+      # Create sensor to get HPWH airflow rate
+      hpwh = model.getWaterHeaterHeatPumpWrappedCondensers.find { |h| h.additionalProperties.getFeatureAsString('HPXML_ID').to_s == ducted_hpwh.id }
+      hpwh_flow_rate = Model.add_ems_sensor(
+        model,
+        name: "hpwh_flow_rate_#{i}",
+        output_var_or_meter_name: 'System Node Current Density Volume Flow Rate',
+        key_name: hpwh.airOutletNodeName
+      )
+
+      infil_program.addLine("Set Qhpwh = Qhpwh + #{hpwh_flow_rate.name} / #{unit_multiplier}")
+    end
+
     infil_program.addLine("Set QWHV_sup = #{UnitConversions.convert(sup_cfm_tot + bal_cfm_tot + erv_hrv_cfm_tot, 'cfm', 'm^3/s').round(5)}")
     infil_program.addLine("Set QWHV_exh = #{UnitConversions.convert(exh_cfm_tot + bal_cfm_tot + erv_hrv_cfm_tot, 'cfm', 'm^3/s').round(5)}")
 
     # Ventilation fans
     infil_program.addLine('Set Qsupply = QWHV_sup + QWHV_cfis_sup + QWHV_cfis_suppl_sup')
-    infil_program.addLine('Set Qexhaust = Qrange + Qbath + Qdryer + QWHV_exh + QWHV_cfis_suppl_exh')
+    infil_program.addLine('Set Qexhaust = Qrange + Qbath + Qdryer + Qhpwh + QWHV_exh + QWHV_cfis_suppl_exh')
     infil_program.addLine('Set Qfan = (@Max Qexhaust Qsupply)')
 
     # Duct leakage imbalance induced infiltration

HPXMLtoOpenStudio/resources/defaults.rb

@@ -3357,10 +3357,10 @@ def self.apply_water_heaters(hpxml_bldg, eri_version, schedules_file)
           water_heating_system.tank_volume_isdefaulted = true
         end
 
-        schedules_file_includes_water_heater_operating_mode = (schedules_file.nil? ? false : schedules_file.includes_col_name(SchedulesFile::Columns[:WaterHeaterOperatingMode].name))
-        if water_heating_system.operating_mode.nil? && !schedules_file_includes_water_heater_operating_mode
-          water_heating_system.operating_mode = HPXML::WaterHeaterOperatingModeHybridAuto
-          water_heating_system.operating_mode_isdefaulted = true
+        schedules_file_includes_water_heater_operating_mode = (schedules_file.nil? ? false : schedules_file.includes_col_name(SchedulesFile::Columns[:WaterHeaterHPWHOperatingMode].name))
+        if water_heating_system.hpwh_operating_mode.nil? && !schedules_file_includes_water_heater_operating_mode
+          water_heating_system.hpwh_operating_mode = HPXML::WaterHeaterHPWHOperatingModeHybridAuto
+          water_heating_system.hpwh_operating_mode_isdefaulted = true
         end
 
         if water_heating_system.hpwh_confined_space_without_mitigation.nil?

HPXMLtoOpenStudio/resources/hpxml.rb

@@ -487,8 +487,8 @@ class HPXML < Object
   WallTypeWoodStud = 'WoodStud'
   WaterFixtureTypeFaucet = 'faucet'
   WaterFixtureTypeShowerhead = 'shower head'
-  WaterHeaterOperatingModeHybridAuto = 'hybrid/auto'
-  WaterHeaterOperatingModeHeatPumpOnly = 'heat pump only'
+  WaterHeaterHPWHOperatingModeHybridAuto = 'hybrid/auto'
+  WaterHeaterHPWHOperatingModeHeatPumpOnly = 'heat pump only'
   WaterHeaterTankModelTypeMixed = 'mixed'
   WaterHeaterTankModelTypeStratified = 'stratified'
   WaterHeaterTypeCombiStorage = 'space-heating boiler with storage tank'
@@ -8587,7 +8587,9 @@ class WaterHeatingSystem < BaseElement
              :backup_heating_capacity,                # [Double] BackupHeatingCapacity (Btu/hr)
              :energy_factor,                          # [Double] EnergyFactor (frac)
              :uniform_energy_factor,                  # [Double] UniformEnergyFactor (frac)
-             :operating_mode,                         # [String] HPWHOperatingMode (HPXML::WaterHeaterOperatingModeXXX)
+             :hpwh_operating_mode,                    # [String] HPWHOperatingMode (HPXML::WaterHeaterHPWHOperatingModeXXX)
+             :hpwh_ducting_supply,                    # [String] HPWHDucting/SupplyAirSource (HPXML::LocationXXX)
+             :hpwh_ducting_exhaust,                   # [String] HPWHDucting/ExhaustAirTermination (HPXML::LocationXXX)
              :first_hour_rating,                      # [Double] FirstHourRating (gal/hr)
              :usage_bin,                              # [String] UsageBin (HPXML::WaterHeaterUsageBinXXX)
              :recovery_efficiency,                    # [Double] RecoveryEfficiency (frac)
@@ -8688,7 +8690,12 @@ def to_doc(building)
       XMLHelper.add_element(water_heating_system, 'BackupHeatingCapacity', @backup_heating_capacity, :float, @backup_heating_capacity_isdefaulted) unless @backup_heating_capacity.nil?
       XMLHelper.add_element(water_heating_system, 'EnergyFactor', @energy_factor, :float, @energy_factor_isdefaulted) unless @energy_factor.nil?
       XMLHelper.add_element(water_heating_system, 'UniformEnergyFactor', @uniform_energy_factor, :float) unless @uniform_energy_factor.nil?
-      XMLHelper.add_element(water_heating_system, 'HPWHOperatingMode', @operating_mode, :string, @operating_mode_isdefaulted) unless @operating_mode.nil?
+      XMLHelper.add_element(water_heating_system, 'HPWHOperatingMode', @hpwh_operating_mode, :string, @hpwh_operating_mode_isdefaulted) unless @hpwh_operating_mode.nil?
+      if (not @hpwh_ducting_exhaust.nil?) || (not @hpwh_ducting_supply.nil?)
+        hpwh_ducting = XMLHelper.add_element(water_heating_system, 'HPWHDucting')
+        XMLHelper.add_element(hpwh_ducting, 'SupplyAirSource', @hpwh_ducting_supply, :string, @hpwh_ducting_supply_isdefaulted) unless @hpwh_ducting_supply.nil?
+        XMLHelper.add_element(hpwh_ducting, 'ExhaustAirTermination', @hpwh_ducting_exhaust, :string, @hpwh_ducting_exhaust_isdefaulted) unless @hpwh_ducting_exhaust.nil?
+      end
       XMLHelper.add_element(water_heating_system, 'FirstHourRating', @first_hour_rating, :float) unless @first_hour_rating.nil?
       XMLHelper.add_element(water_heating_system, 'UsageBin', @usage_bin, :string, @usage_bin_isdefaulted) unless @usage_bin.nil?
       XMLHelper.add_element(water_heating_system, 'RecoveryEfficiency', @recovery_efficiency, :float, @recovery_efficiency_isdefaulted) unless @recovery_efficiency.nil?
@@ -8738,7 +8745,9 @@ def from_doc(water_heating_system)
       @backup_heating_capacity = XMLHelper.get_value(water_heating_system, 'BackupHeatingCapacity', :float)
       @energy_factor = XMLHelper.get_value(water_heating_system, 'EnergyFactor', :float)
       @uniform_energy_factor = XMLHelper.get_value(water_heating_system, 'UniformEnergyFactor', :float)
-      @operating_mode = XMLHelper.get_value(water_heating_system, 'HPWHOperatingMode', :string)
+      @hpwh_operating_mode = XMLHelper.get_value(water_heating_system, 'HPWHOperatingMode', :string)
+      @hpwh_ducting_supply = XMLHelper.get_value(water_heating_system, 'HPWHDucting/SupplyAirSource', :string)
+      @hpwh_ducting_exhaust = XMLHelper.get_value(water_heating_system, 'HPWHDucting/ExhaustAirTermination', :string)
       @first_hour_rating = XMLHelper.get_value(water_heating_system, 'FirstHourRating', :float)
       @usage_bin = XMLHelper.get_value(water_heating_system, 'UsageBin', :string)
       @recovery_efficiency = XMLHelper.get_value(water_heating_system, 'RecoveryEfficiency', :float)

HPXMLtoOpenStudio/resources/hpxml_schematron/EPvalidator.sch

@@ -2587,6 +2587,7 @@
       <sch:assert role='ERROR' test='number(h:EnergyFactor) &gt; 1 or not(h:EnergyFactor)'>Expected EnergyFactor to be greater than 1</sch:assert>
       <sch:assert role='ERROR' test='count(h:HPWHOperatingMode) &lt;= 1'>Expected 0 or 1 element(s) for xpath: HPWHOperatingMode</sch:assert>
       <sch:assert role='ERROR' test='h:HPWHOperatingMode[text()="hybrid/auto" or text()="heat pump only"] or not(h:HPWHOperatingMode)'>Expected HPWHOperatingMode to be 'hybrid/auto' or 'heat pump only'</sch:assert>
+      <sch:assert role='ERROR' test='count(h:HPWHDucting/h:ExhaustAirTermination) &lt;= 1'>Expected 0 or 1 element(s) for xpath: HPWHDucting/ExhaustAirTermination</sch:assert>
       <sch:assert role='ERROR' test='count(h:UsageBin) + count(h:FirstHourRating) &gt;= 0'>Expected 0 or more element(s) for xpath: UsageBin | FirstHourRating</sch:assert>
       <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>

HPXMLtoOpenStudio/resources/model.rb

@@ -1199,7 +1199,13 @@ def self.create_adjacent_surfaces_for_whole_mf_building(merged_model_objects, hp
   # @param unit_number [Integer] index number corresponding to an HPXML Building object
   # @return [String] the new OpenStudio object name with unique unit prefix
   def self.make_variable_name(obj_name, unit_number)
-    return ems_friendly_name("unit#{unit_number + 1}_#{obj_name}")
+    new_name = ems_friendly_name("unit#{unit_number + 1}_#{obj_name}")
+
+    # Need to fix HWPH outlet node name
+    if new_name.include?('_Outlet') && new_name.include?(ems_friendly_name(Constants::ObjectTypeWaterHeater))
+      new_name.gsub!('_Outlet', ' Outlet')
+    end
+    return new_name
   end
 
   # Prefix all object names using using a provided unit number.

HPXMLtoOpenStudio/resources/schedules.rb

@@ -1015,7 +1015,7 @@ def initialize(name, used_by_unavailable_periods, can_be_stochastic, type)
     HeatingSetpoint: Column.new('heating_setpoint', false, false, :setpoint),
     CoolingSetpoint: Column.new('cooling_setpoint', false, false, :setpoint),
     WaterHeaterSetpoint: Column.new('water_heater_setpoint', false, false, :setpoint),
-    WaterHeaterOperatingMode: Column.new('water_heater_operating_mode', false, false, :zero_or_one),
+    WaterHeaterHPWHOperatingMode: Column.new('water_heater_operating_mode', false, false, :zero_or_one),
     Battery: Column.new('battery', false, false, :neg_one_to_one),
     BatteryCharging: Column.new('battery_charging', true, false, nil),
     BatteryDischarging: Column.new('battery_discharging', true, false, nil),