SupplementalFanRunsWithAirHandlerFan input for CFIS systems

Changelog.md

@@ -19,6 +19,7 @@ __New Features__
 - Central Fan Integrated Supply (CFIS) mechanical ventilation enhancements:
   - CFIS systems without automatic flow control of outdoor air (`CFISControls/HasOutdoorAirControl=false`).
   - CFIS systems with no strategy to meet remainder of ventilation target (`CFISControls/AdditionalRuntimeOperatingMode="none"`).
+  - CFIS systems with supplemental fans that run simultaneously with the air handler (`CFISControls/extension/SupplementalFanRunsWithAirHandlerFan=true`).
 - HVAC Manual J design load and sizing calculations:
   - Adds optional `DistributionSystemType/AirDistribution/extension/ManualJInputs/BlowerFanHeatBtuh` input.
   - Adds optional `DistributionSystemType/HydronicDistribution/extension/ManualJInputs/HotWaterPipingBtuh` input.

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>e7d819f6-fda2-4bf2-b6c3-cd1ff3adb569</version_id>
-  <version_modified>2024-10-22T17:43:11Z</version_modified>
+  <version_id>6f307da4-b354-4c31-897f-de2161a9de82</version_id>
+  <version_modified>2024-10-22T21:49:52Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -189,7 +189,7 @@
       <filename>airflow.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>D2A99996</checksum>
+      <checksum>FFA79541</checksum>
     </file>
     <file>
       <filename>battery.rb</filename>
@@ -327,7 +327,7 @@
       <filename>defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>5B6D3CB2</checksum>
+      <checksum>E52E98C6</checksum>
     </file>
     <file>
       <filename>energyplus.rb</filename>
@@ -357,7 +357,7 @@
       <filename>hpxml.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>E862E878</checksum>
+      <checksum>656CF61F</checksum>
     </file>
     <file>
       <filename>hpxml_schema/HPXML.xsd</filename>
@@ -375,7 +375,7 @@
       <filename>hpxml_schematron/EPvalidator.xml</filename>
       <filetype>xml</filetype>
       <usage_type>resource</usage_type>
-      <checksum>009BEB48</checksum>
+      <checksum>DD7BB2F9</checksum>
     </file>
     <file>
       <filename>hpxml_schematron/iso-schematron.xsd</filename>
@@ -663,7 +663,7 @@
       <filename>test_defaults.rb</filename>
       <filetype>rb</filetype>
       <usage_type>test</usage_type>
-      <checksum>9D489184</checksum>
+      <checksum>77AFEE2C</checksum>
     </file>
     <file>
       <filename>test_enclosure.rb</filename>

HPXMLtoOpenStudio/resources/airflow.rb

@@ -725,7 +725,7 @@ def self.create_return_air_duct_zone(model, loop_name, unit_multiplier, adiabati
   # @param unavailable_periods [HPXML::UnavailablePeriods] Object that defines periods for, e.g., power outages or vacancies
   # @return [TODO] TODO
   def self.initialize_cfis(model, vent_fans, airloop_map, unavailable_periods)
-    cfis_data = { airloop: {}, t_sum_open_damper_var: {}, f_extra_open_damper_var: {} }
+    cfis_data = { airloop: {}, t_sum_open_damper_var: {}, f_vent_only_mode_var: {} }
     return cfis_data if vent_fans[:mech].empty?
 
     index = 0
@@ -745,19 +745,19 @@ def self.initialize_cfis(model, vent_fans, airloop_map, unavailable_periods)
       cfis_data[:t_sum_open_damper_var][vent_mech.id] = Model.add_ems_global_var(
         model,
         var_name: "#{Constants::ObjectTypeMechanicalVentilation} cfis t sum open damper #{index}"
-      ) # Sums the time during an hour the CFIS damper has been open
-      cfis_data[:f_extra_open_damper_var][vent_mech.id] = Model.add_ems_global_var(
+      )
+      cfis_data[:f_vent_only_mode_var][vent_mech.id] = Model.add_ems_global_var(
         model,
-        var_name: "#{Constants::ObjectTypeMechanicalVentilation} cfis f open damper #{index}"
-      ) # Fraction of timestep the CFIS blower is running while hvac is not operating. Used by infiltration and duct leakage programs
+        var_name: "#{Constants::ObjectTypeMechanicalVentilation} cfis f vent only mode #{index}"
+      )
 
       # CFIS Initialization Program
       cfis_program = Model.add_ems_program(
         model,
         name: "#{Constants::ObjectTypeMechanicalVentilation} cfis init program #{index}"
       )
       cfis_program.addLine("Set #{cfis_data[:t_sum_open_damper_var][vent_mech.id].name} = 0")
-      cfis_program.addLine("Set #{cfis_data[:f_extra_open_damper_var][vent_mech.id].name} = 0")
+      cfis_program.addLine("Set #{cfis_data[:f_vent_only_mode_var][vent_mech.id].name} = 0")
 
       Model.add_ems_program_calling_manager(
         model,
@@ -1585,12 +1585,12 @@ def self.apply_duct_location(model, spaces, hpxml_bldg, ducts, object, i, duct_l
 
       add_cfis_duct_losses = (cfis_fan.cfis_addtl_runtime_operating_mode == HPXML::CFISModeAirHandler)
       if add_cfis_duct_losses
-        # Calculate CFIS duct losses when the outdoor air damper is open
-        f_extra_open_damper_var = cfis_data[:f_extra_open_damper_var][cfis_id]
+        # Calculate additional CFIS duct losses when the air handler is in ventilation only mode
+        f_vent_only_mode_var = cfis_data[:f_vent_only_mode_var][cfis_id]
 
-        duct_program.addLine("If #{f_extra_open_damper_var.name} > 0")
+        duct_program.addLine("If #{f_vent_only_mode_var.name} > 0")
         duct_program.addLine("  Set cfis_m3s = (#{fan_data[:mfr_max_var][object].name} * #{cfis_fan.cfis_vent_mode_airflow_fraction} / 1.16097654)") # Density of 1.16097654 was back calculated using E+ results
-        duct_program.addLine("  Set #{fan_data[:rtf_var][object].name} = #{f_extra_open_damper_var.name}") # Need to use global vars to sync duct_program and infiltration program of different calling points
+        duct_program.addLine("  Set #{fan_data[:rtf_var][object].name} = #{f_vent_only_mode_var.name}") # Need to use global vars to sync duct_program and infiltration program of different calling points
         duct_program.addLine("  Set #{ah_vfr_var.name} = #{fan_data[:rtf_var][object].name}*cfis_m3s")
         duct_program.addLine("  Set rho_in = (@RhoAirFnPbTdbW #{sensors[:pbar].name} #{sensors[:t_in].name} #{sensors[:w_in].name})")
         duct_program.addLine("  Set #{ah_mfr_var.name} = #{ah_vfr_var.name} * rho_in")
@@ -1978,44 +1978,46 @@ def self.apply_cfis(runner, infil_program, vent_mech_fans, cfis_data, cfis_fan_a
       end
 
       t_sum_open_damper_var = cfis_data[:t_sum_open_damper_var][vent_mech.id]
-      f_extra_open_damper_var = cfis_data[:f_extra_open_damper_var][vent_mech.id]
+      f_vent_only_mode_var = cfis_data[:f_vent_only_mode_var][vent_mech.id]
 
       infil_program.addLine('If @ABS(Minute - ZoneTimeStep*60) < 0.1')
       infil_program.addLine("  Set #{t_sum_open_damper_var.name} = 0") # New hour, time on summation re-initializes to 0
       infil_program.addLine('EndIf')
 
       infil_program.addLine("Set t_min_hr_open = #{[vent_mech.hours_in_operation / 24.0 * 60.0, 59.999].min}") # Minimum CFIS damper open time in minutes
       infil_program.addLine("Set Q_duct_oa = #{UnitConversions.convert(vent_mech.oa_unit_flow_rate, 'cfm', 'm^3/s')}")
-      infil_program.addLine('Set f_total_open_damper = 0') # Fraction of the timestep the CFIS damper is open
-      infil_program.addLine("Set #{f_extra_open_damper_var.name} = 0")
+      infil_program.addLine('Set f_open_damper = 0')
+      infil_program.addLine("Set #{f_vent_only_mode_var.name} = 0")
       infil_program.addLine("Set has_additional_runtime = #{vent_mech.cfis_addtl_runtime_operating_mode == HPXML::CFISModeNone ? 0 : 1}")
       infil_program.addLine("Set has_outdoor_air_control = #{vent_mech.cfis_has_outdoor_air_control ? 1 : 0}")
+      if vent_mech.cfis_addtl_runtime_operating_mode == HPXML::CFISModeSupplementalFan
+        infil_program.addLine("Set suppl_fan_w = #{vent_mech.cfis_supplemental_fan.unit_fan_power}") # W
+      end
 
       infil_program.addLine("If #{t_sum_open_damper_var.name} < t_min_hr_open") # Check whether we've met the minimum hourly runtime
       infil_program.addLine("  Set t_damper_open = 60 - (t_min_hr_open - #{t_sum_open_damper_var.name})") # Minute of the hour at which the damper must be opened
       infil_program.addLine('  If ((Minute+0.00001) >= t_damper_open) && (has_additional_runtime == 1)') # Check whether the damper must be opened to achieve target minutes per hour of operation
-      infil_program.addLine('    Set open_damper_runtime = @Max (@ABS(Minute - t_damper_open)) (fan_rtf_hvac * ZoneTimeStep * 60)') # How many minutes this hour the damper is open
+      infil_program.addLine('    Set open_damper_runtime = @Max (@ABS(Minute - t_damper_open)) (fan_rtf_hvac * ZoneTimeStep * 60)') # How many minutes this timestep the damper is open
       infil_program.addLine("    Set open_damper_runtime = @Min open_damper_runtime (t_min_hr_open - #{t_sum_open_damper_var.name})") # Make sure it's not exceeding target ventilation
-      infil_program.addLine('    Set f_total_open_damper = open_damper_runtime / (60.0 * ZoneTimeStep)') # Fraction of the timestep that the damper is open
-      infil_program.addLine("    Set #{t_sum_open_damper_var.name} = #{t_sum_open_damper_var.name} + open_damper_runtime")
-      infil_program.addLine("    Set #{f_extra_open_damper_var.name} = @Max (f_total_open_damper - fan_rtf_hvac) 0.0") # Fraction of the timestep with additional ventilation mode runtime
+      infil_program.addLine("    Set #{t_sum_open_damper_var.name} = #{t_sum_open_damper_var.name} + open_damper_runtime") # How many minutes this hour the damper is open
+      infil_program.addLine('    Set f_open_damper = open_damper_runtime / (60.0 * ZoneTimeStep)') # Fraction of the timestep that the damper is open
+      infil_program.addLine("    Set #{f_vent_only_mode_var.name} = @Max (f_open_damper - fan_rtf_hvac) 0.0") # Fraction of the timestep with ventilation only mode runtime
       if vent_mech.cfis_addtl_runtime_operating_mode == HPXML::CFISModeAirHandler
         # Air handler meets additional runtime requirement
         infil_program.addLine("    Set fan_w = #{vent_mech.unit_fan_power}") # W
-        infil_program.addLine("    Set #{cfis_fan_actuator.name} = #{cfis_fan_actuator.name} + fan_w * #{f_extra_open_damper_var.name}")
+        infil_program.addLine("    Set #{cfis_fan_actuator.name} = #{cfis_fan_actuator.name} + fan_w * #{f_vent_only_mode_var.name}")
       elsif vent_mech.cfis_addtl_runtime_operating_mode == HPXML::CFISModeSupplementalFan
         # Supplemental fan meets additional runtime requirement
         if vent_mech.cfis_supplemental_fan.oa_unit_flow_rate < vent_mech.average_unit_flow_rate
           runner.registerWarning("CFIS supplemental fan '#{vent_mech.cfis_supplemental_fan.id}' is undersized (#{vent_mech.cfis_supplemental_fan.oa_unit_flow_rate} cfm) compared to the target hourly ventilation rate (#{vent_mech.average_unit_flow_rate} cfm).")
         end
         infil_program.addLine("    Set suppl_Q_oa = #{UnitConversions.convert(vent_mech.cfis_supplemental_fan.oa_unit_flow_rate, 'cfm', 'm^3/s')}")
         if vent_mech.cfis_supplemental_fan.oa_unit_flow_rate > 0
-          infil_program.addLine("    Set suppl_f = #{f_extra_open_damper_var.name} / (suppl_Q_oa / Q_duct_oa)") # Calculate desired runtime for supplemental fan to provide remaining ventilation requirement
+          infil_program.addLine("    Set suppl_f = #{f_vent_only_mode_var.name} / (suppl_Q_oa / Q_duct_oa)") # Calculate desired runtime for supplemental fan to provide remaining ventilation requirement
           infil_program.addLine('    Set suppl_f = @Min suppl_f 1.0') # Ensure desired runtime does not exceed 100% (if the supplemental fan is undersized)
         else
           infil_program.addLine('    Set suppl_f = 0.0')
         end
-        infil_program.addLine("    Set suppl_fan_w = #{vent_mech.cfis_supplemental_fan.unit_fan_power}") # W
         infil_program.addLine("    Set #{cfis_suppl_fan_actuator.name} = #{cfis_suppl_fan_actuator.name} + suppl_fan_w * suppl_f")
         if vent_mech.cfis_supplemental_fan.fan_type == HPXML::MechVentTypeSupply
           infil_program.addLine('    Set QWHV_cfis_suppl_sup = QWHV_cfis_suppl_sup + (suppl_f * suppl_Q_oa)')
@@ -2024,21 +2026,39 @@ def self.apply_cfis(runner, infil_program, vent_mech_fans, cfis_data, cfis_fan_a
         end
       end
       infil_program.addLine('  Else') # No additional ventilation mode runtime
-      infil_program.addLine('    Set open_damper_runtime = fan_rtf_hvac * ZoneTimeStep * 60') # How many minutes this hour the damper is open
+      infil_program.addLine('    Set open_damper_runtime = fan_rtf_hvac * ZoneTimeStep * 60') # How many minutes this timestep the damper is open
       infil_program.addLine("    If (#{t_sum_open_damper_var.name} + open_damper_runtime) > t_min_hr_open") # Damper is only open for a portion of this time step to achieve target ventilation
       infil_program.addLine("      Set open_damper_runtime = t_min_hr_open - #{t_sum_open_damper_var.name}")
       infil_program.addLine('    EndIf')
-      infil_program.addLine('    Set f_total_open_damper = open_damper_runtime / (ZoneTimeStep * 60)') # Fraction of the timestep that the damper is open
-      infil_program.addLine("    Set #{t_sum_open_damper_var.name} = #{t_sum_open_damper_var.name} + open_damper_runtime")
+      infil_program.addLine('    Set f_open_damper = open_damper_runtime / (ZoneTimeStep * 60)') # Fraction of the timestep that the damper is open
+      infil_program.addLine("    Set #{t_sum_open_damper_var.name} = #{t_sum_open_damper_var.name} + open_damper_runtime") # How many minutes this hour the damper is open
       infil_program.addLine('  EndIf')
+      infil_program.addLine('EndIf')
+
+      # Calculate fraction of the timestep that the damper is open and the air handler fan is running
       if vent_mech.cfis_addtl_runtime_operating_mode == HPXML::CFISModeSupplementalFan
-        infil_program.addLine("  Set f_total_open_damper = @Max (f_total_open_damper - #{f_extra_open_damper_var.name}) 0.0")
+        infil_program.addLine("Set f_open_damper_ah = @Max (f_open_damper - #{f_vent_only_mode_var.name}) 0.0")
+      else
+        infil_program.addLine('Set f_open_damper_ah = f_open_damper')
       end
-      infil_program.addLine('EndIf')
+
+      # If no outdoor air control, then outdoor air is introduced for at least the entire time the HVAC system is running
       infil_program.addLine('If has_outdoor_air_control == 0')
-      infil_program.addLine('  Set f_total_open_damper = @Max f_total_open_damper fan_rtf_hvac') # Outdoor air is introduced for at least the entire time the HVAC system is running
+      infil_program.addLine('  Set f_open_damper_ah = @Max f_open_damper_ah fan_rtf_hvac')
       infil_program.addLine('EndIf')
-      infil_program.addLine('Set QWHV_cfis_sup = QWHV_cfis_sup + (f_total_open_damper * Q_duct_oa)')
+
+      # Airflow brought in through air handler
+      infil_program.addLine('Set QWHV_cfis_sup = QWHV_cfis_sup + (f_open_damper_ah * Q_duct_oa)')
+
+      next unless vent_mech.cfis_addtl_runtime_operating_mode == HPXML::CFISModeSupplementalFan && vent_mech.cfis_supplemental_fan_runs_with_air_handler_fan
+
+      # Also run supplemental fan when damper is open and HVAC system is running
+      infil_program.addLine("Set #{cfis_suppl_fan_actuator.name} = #{cfis_suppl_fan_actuator.name} + (suppl_fan_w * f_open_damper_ah)")
+      if vent_mech.cfis_supplemental_fan.fan_type == HPXML::MechVentTypeSupply
+        infil_program.addLine('Set QWHV_cfis_suppl_sup = QWHV_cfis_suppl_sup + (f_open_damper_ah * suppl_Q_oa)')
+      elsif vent_mech.cfis_supplemental_fan.fan_type == HPXML::MechVentTypeExhaust
+        infil_program.addLine('Set QWHV_cfis_suppl_exh = QWHV_cfis_suppl_exh + (f_open_damper_ah * suppl_Q_oa)')
+      end
     end
   end
 

HPXMLtoOpenStudio/resources/defaults.rb

@@ -2755,6 +2755,10 @@ def self.apply_ventilation_fans(hpxml_bldg, weather, eri_version)
         vent_fan.cfis_vent_mode_airflow_fraction = 1.0
         vent_fan.cfis_vent_mode_airflow_fraction_isdefaulted = true
       end
+      if vent_fan.cfis_supplemental_fan_runs_with_air_handler_fan.nil? && (vent_fan.cfis_addtl_runtime_operating_mode == HPXML::CFISModeSupplementalFan)
+        vent_fan.cfis_supplemental_fan_runs_with_air_handler_fan = false
+        vent_fan.cfis_supplemental_fan_runs_with_air_handler_fan_isdefaulted = true
+      end
     end
 
     # Default kitchen fan