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Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints

Output setpoints for AHU control

Information

This package contains sequences generating setpoints for VAV AHU control.

Package Content

Name Description
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.FreezeProtection FreezeProtection Freeze protection sequence for multizone air handling unit
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.PlantRequests PlantRequests Output plant requests for multizone air handling unit
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefDamper ReliefDamper Relief damper control for AHUs using actuated dampers without fan
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFan ReliefFan Sequence for control of relief fan in AHU
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFanGroup ReliefFanGroup Sequence for controlling relief fan group
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanAirflowTracking ReturnFanAirflowTracking Return fan control for AHUs using return fan with airflow tracking
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanDirectPressure ReturnFanDirectPressure Return fan control with direct building pressure control
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyFan SupplyFan Block to control multi zone VAV AHU supply fan
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplySignals SupplySignals Multizone VAV AHU supply air temperature control loop and coil valves position
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyTemperature SupplyTemperature Supply air temperature setpoint for multi zone system
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.OutdoorAirFlow OutdoorAirFlow Package of sequences for calculating minimum outdoor airflow rate
Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.Validation Validation Collection of validation models

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.FreezeProtection Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.FreezeProtection

Freeze protection sequence for multizone air handling unit

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.FreezeProtection

Information

Freeze protection sequence for multizone AHU system. It is developed based on Section 5.16.12 of ASHRAE Guideline 36, May 2020.

  1. If the supply air temperature TAirSup drops below 4.4 °C (40 °F) for 5 minutes, send two (or more, as required to ensure that heating plant is active, minHotWatReq) heating hot-water plant requests, override the outdoor air damper to the minimum position, and modulate the heating coil to maintain a suppy air temperature of at least 6 °C (42 °F). Disable this function when supply air temperature rises above 7 °C (45 °F) for 5 minutes.
  2. If the supply air temperature TAirSup drops below 3.3 °C (38 °F) for 5 minutes, fully close both the economizer damper and the minimum outdoor air damper for 1 hour and set a Level 3 alarm noting that minimum ventilation was interrupted. After 1 hour, the unit shall resume minimum outdoor air ventilation and enter the previous stage of freeze protection.
    • If it is warm enough that the supply air temperature rises above 7 °C (45 °F) with minimum ventilation, the unit will remain in Stage 1 freeze protection for 5 minutes then resume normal operation.
  3. Upon signal from the freeze-stat (if installed), or if supply air temperature drops below 3.3 °C (38 °F) for 15 minutes or below 1 °C (34 °F) for 5 minutes, shut down supply and return (or relief) fan(s), close outdoor air damper, open the cooling-coil valve to 100%, and energize the CHW pump system. Also send two (or more, as required to ensure that heating plant is active, minHotWatReq) heating hot-water plant requests, modulate the heating coil to maintain the higher of the supply air temperature or the mixed air temperature at 27 °C (80 °F), and set a Level 2 alarm indicating the unit is shut down by freeze protection.
    • If a freeze-protection shutdown is triggered by a low air temperature sensor reading, it shall remain in effect until it is reset by a software switch from the operator's workstation. (If a freeze-stat with a physical reset switch is used instead, there shall be no software reset switch.)

Parameters

TypeNameDefaultDescription
Booleanhave_freProtrueTrue: enable freeze protection
BuildingPressureControlTypesbuiPreConBuildings.Controls.OBC.ASHRA...Type of building pressure control system
OutdoorAirSectionminOADesBuildings.Controls.OBC.ASHRA...Design of minimum outdoor air and economizer function
FreezeStatfreStaBuildings.Controls.OBC.ASHRA...Type of freeze stat
Booleanhave_hotWatCoitrueTrue: the AHU has heating coil
IntegerminHotWatReq2Minimum heating hot-water plant request to active the heating plant
Heating coil controller
SimpleControllerheaCoiConBuildings.Controls.OBC.CDL.T...Heating coil controller
Realk1Gain of coil controller [1]
RealTi0.5Time constant of integrator block [s]
RealTd0.1Time constant of derivative block [s]
RealyMax1Upper limit of output
RealyMin0Lower limit of output
Advanced
RealThys0.25Hysteresis for checking temperature difference [K]

Connectors

TypeNameDescription
input RealInputuOutDamPosMinMinimum economizer damper position limit as returned by the damper position limits sequence [1]
input RealInputuOutDamEconomizer outdoor air damper commanded position [1]
input RealInputuHeaCoiHeating coil commanded position [1]
input RealInputuMinOutDamMinimum outdoor air damper commanded position [1]
input BooleanInputu1MinOutDamMinimum outdoor air damper command on position
input RealInputuRetDamEconomizer return air damper commanded position [1]
input RealInputTAirSupMeasured supply air temperature [K]
input BooleanInputu1FreStaFreeze protection stat signal. The stat is normally close (the input is normally true), when enabling freeze protection, the input becomes false
input BooleanInputu1SofSwiResFreeze protection reset signal from software switch
input BooleanInputu1SupFanSupply fan commanded on
input RealInputuSupFanSupply fan commanded speed [1]
input BooleanInputu1RetFanReturn fan commanded on
input RealInputuRetFanReturn fan commanded speed [1]
input BooleanInputu1RelFanRelief fan commanded on
input RealInputuRelFanRelief fan commanded speed [1]
input RealInputuCooCoiCooling coil commanded position [1]
input RealInputTAirMixMeasured mixed air temperature [K]
output IntegerOutputyFreProStaFreeze protection stage index
output BooleanOutputy1EneCHWPumCommanded on to energize chilled water pump
output RealOutputyRetDamReturn air damper commanded position [1]
output RealOutputyOutDamOutdoor air damper commanded position [1]
output RealOutputyMinOutDamMinimum outdoor air damper commanded position [1]
output BooleanOutputy1MinOutDamMinimum outdoor air damper command on position
output BooleanOutputy1SupFanSupply fan commanded on
output RealOutputySupFanSupply fan commanded speed [1]
output BooleanOutputy1RetFanReturn fan commanded on
output RealOutputyRetFanReturn fan commanded speed [1]
output BooleanOutputy1RelFanRelief fan commanded on
output RealOutputyRelFanRelief fan commanded speed [1]
output RealOutputyCooCoiCooling coil commanded position [1]
output RealOutputyHeaCoiHeating coil commanded position [1]
output IntegerOutputyHotWatPlaReqRequest to heating hot-water plant
output IntegerOutputyAlaAlarm level

Modelica definition

block FreezeProtection "Freeze protection sequence for multizone air handling unit" parameter Boolean have_frePro=true "True: enable freeze protection"; parameter Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes buiPreCon=Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefDamper "Type of building pressure control system"; parameter Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection minOADes=Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow "Design of minimum outdoor air and economizer function"; parameter Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat freSta=Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.No_freeze_stat "Type of freeze stat"; parameter Boolean have_hotWatCoi=true "True: the AHU has heating coil"; parameter Integer minHotWatReq=2 "Minimum heating hot-water plant request to active the heating plant"; parameter Buildings.Controls.OBC.CDL.Types.SimpleController heaCoiCon=Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Heating coil controller"; parameter Real k(unit="1")=1 "Gain of coil controller"; parameter Real Ti(unit="s")=0.5 "Time constant of integrator block"; parameter Real Td(unit="s")=0.1 "Time constant of derivative block"; parameter Real yMax=1 "Upper limit of output"; parameter Real yMin=0 "Lower limit of output"; parameter Real Thys(unit="K")=0.25 "Hysteresis for checking temperature difference"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uOutDamPosMin( final min=0, final max=1, final unit="1") if have_frePro "Minimum economizer damper position limit as returned by the damper position limits sequence"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uOutDam( final min=0, final max=1, final unit="1") "Economizer outdoor air damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uHeaCoi( final min=0, final max=1, final unit="1") if have_hotWatCoi "Heating coil commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uMinOutDam( final min=0, final max=1, final unit="1") if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow "Minimum outdoor air damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1MinOutDam if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersPressure "Minimum outdoor air damper command on position"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uRetDam( final min=0, final max=1, final unit="1") "Economizer return air damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealInput TAirSup( final unit="K", final displayUnit="degC", final quantity="ThermodynamicTemperature") if have_frePro "Measured supply air temperature"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1FreSta if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_BAS and have_frePro "Freeze protection stat signal. The stat is normally close (the input is normally true), when enabling freeze protection, the input becomes false"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SofSwiRes if (freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.No_freeze_stat or freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Freeze protection reset signal from software switch"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "Supply fan commanded on"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uSupFan( final min=0, final max=1, final unit="1") "Supply fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1RetFan if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) "Return fan commanded on"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uRetFan( final min=0, final max=1, final unit="1") if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) "Return fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1RelFan if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan "Relief fan commanded on"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uRelFan( final min=0, final max=1, final unit="1") if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan "Relief fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uCooCoi( final min=0, final max=1, final unit="1") "Cooling coil commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealInput TAirMix( final unit="K", final displayUnit="degC", final quantity="ThermodynamicTemperature") if have_hotWatCoi and have_frePro "Measured mixed air temperature"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yFreProSta "Freeze protection stage index"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1EneCHWPum if have_frePro "Commanded on to energize chilled water pump"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRetDam( final min=0, final max=1, final unit="1") "Return air damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yOutDam( final min=0, final max=1, final unit="1") "Outdoor air damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yMinOutDam( final min=0, final max=1, final unit="1") if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow "Minimum outdoor air damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1MinOutDam if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersPressure "Minimum outdoor air damper command on position"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1SupFan "Supply fan commanded on"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput ySupFan( final min=0, final max=1, final unit="1") "Supply fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1RetFan if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) "Return fan commanded on"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRetFan( final min=0, final max=1, final unit="1") if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) "Return fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1RelFan if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan "Relief fan commanded on"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRelFan( final min=0, final max=1, final unit="1") if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan "Relief fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yCooCoi( final min=0, final max=1, final unit="1") "Cooling coil commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yHeaCoi( final min=0, final max=1, final unit="1") if have_hotWatCoi "Heating coil commanded position"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yHotWatPlaReq if have_hotWatCoi and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) "Request to heating hot-water plant"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yAla if have_frePro "Alarm level"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr( final t=273.15 + 4.4, final h=Thys) if have_frePro "Check if supply air temperature is less than threshold"; Buildings.Controls.OBC.CDL.Logical.Timer tim( final t=300) if have_frePro "Check if the supply air temperature has been lower than threshold value for sufficient long time"; Buildings.Controls.OBC.CDL.Integers.Switch hotWatPlaReq if have_hotWatCoi and have_frePro "Hot water plant request in stage 1 mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt( final k=minHotWatReq) if have_hotWatCoi and have_frePro "Minimum hot-water plant requests"; Buildings.Controls.OBC.CDL.Reals.Switch minVen if have_frePro "Minimum ventilation when in stage 1 mode"; Buildings.Controls.OBC.CDL.Reals.PID heaCoiCon1( final controllerType=heaCoiCon, final k=k, final Ti=Ti, final Td=Td, final yMax=yMax, final yMin=yMin) if have_hotWatCoi and have_frePro "Heating coil control in stage 1 mode"; Buildings.Controls.OBC.CDL.Reals.Switch heaCoi1 if have_hotWatCoi and have_frePro "Heating coil position"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr( final t=273.15 + 7, final h=Thys) if have_frePro "Check if supply air temperature is greater than threshold"; Buildings.Controls.OBC.CDL.Logical.Latch lat if have_frePro "Stay in stage 1 freeze protection mode"; Buildings.Controls.OBC.CDL.Logical.Timer tim1( final t=300) if have_frePro "Check if the supply air temperature has been lower than threshold value for sufficient long time"; Buildings.Controls.OBC.CDL.Logical.Edge endStaOne if have_frePro "Clear the latch to end the stage 1 freeze protection"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr1( final t=273.15 + 3.3, final h=Thys) if have_frePro "Check if supply air temperature is less than threshold"; Buildings.Controls.OBC.CDL.Logical.Timer tim2( final t=300) if have_frePro "Check if the supply air temperature has been lower than threshold value for sufficient long time"; Buildings.Controls.OBC.CDL.Logical.TrueFalseHold holSta2( final trueHoldDuration=3600, final falseHoldDuration=0) if have_frePro "Stage in stage 2 freeze protection mode"; Buildings.Controls.OBC.CDL.Reals.Switch outDam2 if have_frePro "Outdoor air damper position"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant con( final k=0) if have_frePro "Fully closed damper position"; Buildings.Controls.OBC.CDL.Reals.Switch minOutDam2 if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow and have_frePro "Minimum outdoor air damper position"; Buildings.Controls.OBC.CDL.Reals.Switch retDam2 if have_frePro "Return air damper position"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant con1( final k=1) if have_frePro "Fully open damper or valve position"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi1 if have_frePro "Alarm when it is in stage 2 mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt1( final k=3) if have_frePro "Level 3 alarm"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt2( final k=0) if have_hotWatCoi and have_frePro "Zero request"; Buildings.Controls.OBC.CDL.Logical.Timer tim3( final t=900) if have_frePro "Check if the supply air temperature has been lower than threshold value for sufficient long time"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr2( final t=273.15 + 1, final h=Thys) if have_frePro "Check if supply air temperature is less than threshold"; Buildings.Controls.OBC.CDL.Logical.Timer tim4( final t=300) if have_frePro "Check if the supply air temperature has been lower than threshold value for sufficient long time"; Buildings.Controls.OBC.CDL.Logical.Or3 or3 if have_frePro "Check if it should be in stage 3 mode"; Buildings.Controls.OBC.CDL.Logical.Sources.Constant con2( final k=false) if not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_BAS and have_frePro "Constant false"; Buildings.Controls.OBC.CDL.Logical.Latch lat1 if have_frePro "Stay in stage 3 freeze protection mode"; Buildings.Controls.OBC.CDL.Reals.Switch supFan if (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Supply fan speed"; Buildings.Controls.OBC.CDL.Reals.Switch retFan if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Return fan speed"; Buildings.Controls.OBC.CDL.Reals.Switch relFan if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Relief fan speed"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant con3( final k=0) if have_frePro "Zero constant"; Buildings.Controls.OBC.CDL.Reals.Switch outDam if not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Outdoor air damper"; Buildings.Controls.OBC.CDL.Reals.Switch cooCoi if not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Cooling coil position"; Buildings.Controls.OBC.CDL.Integers.Switch hotWatPlaReq3 if have_hotWatCoi and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Hot water plant request in stage 3 mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt3( final k=minHotWatReq) if have_hotWatCoi and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Minimum hot-water plant requests"; Buildings.Controls.OBC.CDL.Reals.Max max1 if have_hotWatCoi and have_frePro "Higher of supply air and mixed air temperature"; Buildings.Controls.OBC.CDL.Reals.PID heaCoiMod( final controllerType=heaCoiCon, final k=k, final Ti=Ti, final Td=Td, final yMax=yMax, final yMin=yMin) if have_hotWatCoi and have_frePro "Heating coil control when it is in stage 3 mode"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant con4( final k=273.15 + 27) if have_hotWatCoi and have_frePro "Setpoint temperature"; Buildings.Controls.OBC.CDL.Reals.Switch heaCoiPos if have_hotWatCoi and ( not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Heating coil position"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi3 if have_frePro "Alarm level"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt4( final k=2) if have_frePro "Level 2 alarm"; Buildings.Controls.OBC.CDL.Utilities.Assert shuDowWar( final message="Warning: the unit is shut down by freeze protection!") if have_frePro "Unit shut down warning"; Buildings.Controls.OBC.CDL.Logical.Not not1 if have_frePro "Logical not"; Buildings.Controls.OBC.CDL.Utilities.Assert disMinVenWar( final message="Warning: minimum ventilation was interrupted by freeze protection!") if have_frePro "Warning of disabling minimum ventilation "; Buildings.Controls.OBC.CDL.Logical.Not not2 if have_frePro "Logical not"; Buildings.Controls.OBC.CDL.Logical.Timer tim5( final t=3600) if have_frePro "Check if it has been in stage 2 for sufficient long time"; Buildings.Controls.OBC.CDL.Reals.Switch minOutDam if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Minimum outdoor air damper position"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt5( final k=0) if have_frePro "Level 0 alarm"; Buildings.Controls.OBC.CDL.Logical.Latch lat2 if have_frePro "Stay in stage 2 freeze protection mode"; Buildings.Controls.OBC.CDL.Logical.Edge endStaTwo if have_frePro "Clear the latch to end the stage 2 freeze protection"; Buildings.Controls.OBC.CDL.Logical.Or or2 if have_frePro "Start stage 1 freeze protection mode"; Buildings.Controls.OBC.CDL.Reals.Switch retDam if not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Return air damper position"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant supTemSet( final k=273.15+ 6) if have_hotWatCoi and have_frePro "Supply air temperature setpoint"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi2 if have_frePro "Alarm level"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi4 if have_frePro "Alarm level"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt6( final k=2) if have_frePro "Stage 2 freeze protection"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi5 if have_frePro "Alarm level"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt7( final k=1) if have_frePro "Stage 1 freeze protection"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt8( final k=0) if have_frePro "Stage 0 freeze protection"; Buildings.Controls.OBC.CDL.Logical.Switch minOutDam3 if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersPressure and have_frePro "Minimum outdoor air damper command on position"; Buildings.Controls.OBC.CDL.Logical.Sources.Constant con5( final k=false) if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersPressure and have_frePro "False"; Buildings.Controls.OBC.CDL.Logical.Switch minOutDam1 if (minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersPressure and not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Minimum outdoor air damper command on position"; Buildings.Controls.OBC.CDL.Logical.Not norFal if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_BAS and have_frePro "The output is normally false"; Buildings.Controls.OBC.CDL.Logical.FallingEdge falEdg if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_BAS and have_frePro "Reset the freeze protection by the physical reset switch in freeze stat"; Buildings.Controls.OBC.CDL.Logical.And and1 if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Disable return fan when in stage 3"; Buildings.Controls.OBC.CDL.Logical.Not norSta3 if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) and have_frePro "Not in stage 3"; Buildings.Controls.OBC.CDL.Logical.Not norSta1 if have_frePro "Not in stage 3"; Buildings.Controls.OBC.CDL.Logical.And and2 if (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Disable supply fan when in stage 3"; Buildings.Controls.OBC.CDL.Logical.Not norSta2 if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan) and have_frePro "Not in stage 3"; Buildings.Controls.OBC.CDL.Logical.And and3 if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Disable relief fan when in stage 3"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai( final k=1) if (have_hotWatCoi and freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai1( final k=1) if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai2( final k=1) if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan and freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Logical.Or or1 if buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan and (freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment or not have_frePro) "Dummy block for enabling and disabling conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai3( final k=1) if ((buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) and freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Logical.Or or4 if (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) and (freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment or not have_frePro) "Dummy block for enabling and disabling conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai4( final k=1) if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai5( final k=1) if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai6( final k=1) if (minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersAirflow and freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Logical.Or or5 if minOADes == Buildings.Controls.OBC.ASHRAE.G36.Types.OutdoorAirSection.DedicatedDampersPressure and (freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment or not have_frePro) "Dummy block for enabling and disabling conditional connection"; Buildings.Controls.OBC.CDL.Logical.Or or6 if (freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment) or (not have_frePro) "Dummy block for enabling and disabling conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai7( final k=1) if freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment and have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai8(final k=1) if not have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt9(final k=0) if not have_frePro "Dummy constant"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai9(final k=1) if not have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai10(final k=1) if not have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai11(final k=1) if not have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai12(final k=1) if (not have_frePro) and (buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanMeasuredAir or buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReturnFanDp) "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai13(final k=1) if (not have_frePro) and buiPreCon == Buildings.Controls.OBC.ASHRAE.G36.Types.BuildingPressureControlTypes.ReliefFan "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai14(final k=1) if not have_frePro "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai15(final k=1) if (not have_frePro) and have_hotWatCoi "Dummy block for enabling and disabling the conditional connection"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt10(final k=0) if (not have_frePro) and (have_hotWatCoi and (not freSta == Buildings.Controls.OBC.ASHRAE.G36.Types.FreezeStat.Hardwired_to_equipment)) "Dummy constant"; equation connect(lesThr.y, tim.u); connect(TAirSup, lesThr.u); connect(conInt.y, hotWatPlaReq.u1); connect(uOutDamPosMin, minVen.u1); connect(supTemSet.y, heaCoiCon1.u_s); connect(TAirSup, heaCoiCon1.u_m); connect(heaCoiCon1.y, heaCoi1.u1); connect(TAirSup, greThr.u); connect(greThr.y, tim1.u); connect(tim1.passed, endStaOne.u); connect(endStaOne.y, lat.clr); connect(lat.y, hotWatPlaReq.u2); connect(lat.y, minVen.u2); connect(lat.y, heaCoi1.u2); connect(TAirSup, lesThr1.u); connect(lesThr1.y, tim2.u); connect(tim2.passed, holSta2.u); connect(con.y, outDam2.u1); connect(con.y, minOutDam2.u1); connect(con1.y, retDam2.u1); connect(uRetDam, retDam2.u3); connect(conInt1.y, intSwi1.u1); connect(lesThr1.y, tim3.u); connect(lesThr2.y, tim4.u); connect(TAirSup, lesThr2.u); connect(tim3.passed, or3.u1); connect(tim4.passed, or3.u2); connect(con2.y, or3.u3); connect(u1SofSwiRes, lat1.clr); connect(lat1.y, supFan.u2); connect(lat1.y, retFan.u2); connect(lat1.y, relFan.u2); connect(con3.y, supFan.u1); connect(con3.y, retFan.u1); connect(con3.y, relFan.u1); connect(uSupFan, supFan.u3); connect(uRetFan, retFan.u3); connect(uRelFan, relFan.u3); connect(supFan.y, ySupFan); connect(relFan.y, yRelFan); connect(retFan.y, yRetFan); connect(con3.y, outDam.u1); connect(lat1.y, outDam.u2); connect(uCooCoi, cooCoi.u3); connect(lat1.y, cooCoi.u2); connect(con1.y, cooCoi.u1); connect(conInt3.y, hotWatPlaReq3.u1); connect(lat1.y, hotWatPlaReq3.u2); connect(TAirMix, max1.u2); connect(TAirSup, max1.u1); connect(max1.y, heaCoiMod.u_m); connect(con4.y, heaCoiMod.u_s); connect(heaCoiMod.y, heaCoiPos.u1); connect(lat1.y, heaCoiPos.u2); connect(lat1.y, intSwi3.u2); connect(conInt4.y, intSwi3.u1); connect(lat1.y, not1.u); connect(not1.y, shuDowWar.u); connect(not2.y, disMinVenWar.u); connect(holSta2.y, tim5.u); connect(lat1.y, minOutDam.u2); connect(con3.y, minOutDam.u1); connect(uOutDam, minVen.u3); connect(minVen.y, outDam2.u3); connect(outDam2.y, outDam.u3); connect(conInt2.y, hotWatPlaReq.u3); connect(conInt5.y, intSwi1.u3); connect(intSwi1.y, intSwi3.u3); connect(intSwi3.y, yAla); connect(hotWatPlaReq.y, hotWatPlaReq3.u3); connect(hotWatPlaReq3.y, yHotWatPlaReq); connect(minOutDam2.y, minOutDam.u3); connect(minOutDam.y, yMinOutDam); connect(uMinOutDam, minOutDam2.u3); connect(uHeaCoi, heaCoi1.u3); connect(heaCoi1.y, heaCoiPos.u3); connect(heaCoiPos.y, yHeaCoi); connect(holSta2.y, lat2.u); connect(tim5.passed, endStaTwo.u); connect(endStaTwo.y, lat2.clr); connect(lat2.y, outDam2.u2); connect(lat2.y, minOutDam2.u2); connect(lat2.y, not2.u); connect(lat2.y, retDam2.u2); connect(lat2.y, intSwi1.u2); connect(tim.passed, or2.u1); connect(or2.y, lat.u); connect(lat1.y, retDam.u2); connect(con3.y, retDam.u1); connect(retDam2.y, retDam.u3); connect(retDam.y, yRetDam); connect(lat1.y, y1EneCHWPum); connect(outDam.y, yOutDam); connect(cooCoi.y, yCooCoi); connect(conInt1.y, intSwi2.u1); connect(lat1.y, intSwi2.u2); connect(lat2.y, intSwi4.u2); connect(conInt6.y, intSwi4.u1); connect(intSwi4.y, intSwi2.u3); connect(lat.y, intSwi5.u2); connect(intSwi5.y, intSwi4.u3); connect(conInt7.y, intSwi5.u1); connect(intSwi2.y, yFreProSta); connect(conInt8.y, intSwi5.u3); connect(endStaTwo.y, or2.u2); connect(u1MinOutDam, minOutDam3.u3); connect(lat2.y, minOutDam3.u2); connect(con5.y, minOutDam3.u1); connect(lat1.y, minOutDam1.u2); connect(minOutDam1.y, y1MinOutDam); connect(minOutDam3.y, minOutDam1.u3); connect(con5.y, minOutDam1.u1); connect(u1FreSta,norFal. u); connect(or3.y, lat1.u); connect(falEdg.y, lat1.clr); connect(u1RetFan, and1.u1); connect(and1.y, y1RetFan); connect(norSta3.y, and1.u2); connect(lat1.y, norSta3.u); connect(u1SupFan, and2.u1); connect(and2.y, y1SupFan); connect(norSta1.y, and2.u2); connect(lat1.y, norSta1.u); connect(u1RelFan, and3.u1); connect(and3.y, y1RelFan); connect(norSta2.y,and3. u2); connect(lat1.y, norSta2.u); connect(uHeaCoi, gai.u); connect(gai.y, yHeaCoi); connect(uCooCoi, gai1.u); connect(gai1.y, yCooCoi); connect(uRelFan, gai2.u); connect(gai2.y, yRelFan); connect(u1RelFan, or1.u1); connect(u1RelFan, or1.u2); connect(or1.y, y1RelFan); connect(uRetFan, gai3.u); connect(gai3.y, yRetFan); connect(u1RetFan, or4.u1); connect(u1RetFan, or4.u2); connect(or4.y, y1RetFan); connect(uRetDam, gai4.u); connect(gai4.y, yRetDam); connect(uOutDam, gai5.u); connect(gai5.y, yOutDam); connect(uMinOutDam, gai6.u); connect(gai6.y, yMinOutDam); connect(u1MinOutDam, or5.u1); connect(u1MinOutDam, or5.u2); connect(or5.y, y1MinOutDam); connect(u1SupFan, or6.u1); connect(u1SupFan, or6.u2); connect(or6.y, y1SupFan); connect(uSupFan, gai7.u); connect(gai7.y, ySupFan); connect(norFal.y, falEdg.u); connect(norFal.y, or3.u3); connect(conInt9.y, yFreProSta); connect(gai8.y, yRetDam); connect(gai9.y, yOutDam); connect(uRetDam, gai8.u); connect(uOutDam, gai9.u); connect(gai10.y, yMinOutDam); connect(uMinOutDam, gai10.u); connect(gai11.y, ySupFan); connect(uSupFan, gai11.u); connect(uRetFan, gai12.u); connect(gai12.y, yRetFan); connect(uRelFan, gai13.u); connect(gai13.y, yRelFan); connect(uCooCoi, gai14.u); connect(gai14.y, yCooCoi); connect(gai15.y, yHeaCoi); connect(uHeaCoi, gai15.u); connect(conInt10.y, yHotWatPlaReq); end FreezeProtection;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.PlantRequests Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.PlantRequests

Output plant requests for multizone air handling unit

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.PlantRequests

Information

This sequence outputs the system reset requests for multiple zone air handling unit. The implementation is according to the Section 5.16.16 of ASHRAE Guideline 36, May 2020.

chilled water reset request yChiWatResReq

  1. If the supply air temperature TAirSup exceeds the supply air temperature set point TAirSupSet by 3 °C (5 °F) for 2 minutes, send 3 requests.
  2. If the supply air temperature TAirSup exceeds the supply air temperature set point TAirSupSet by 2 °C (3 °F) for 2 minutes, send 2 requests.
  3. Else if the chilled water valve position uCooCoi_actual is greater than 95%, send 1 request until the uCooCoi_actual is less than 85%.
  4. Else if the chilled water valve position uCooCoi_actual is less than 95%, send 0 request.

Chiller plant request yChiPlaReq

Send the chiller plant that serves the system a chiller plant request as follows:

  1. If the chilled water valve position uCooCoi_actual is greater than 95%, send 1 request until the uCooCoi_actual is less than 10%.
  2. Else if the chilled water valve position uCooCoi_actual is less than 95%, send 0 request.

If there is a hot-water coil (have_hotWatCoi=true), hot-water reset requests yHotWatResReq

  1. If the supply air temperature TAirSup is 17 °C (30 °F) less than the supply air temperature set point TAirSupSet for 5 minutes, send 3 requests.
  2. Else if the supply air temperature TAirSup is 8 °C (15 °F) less than the supply air temperature set point TAirSupSet for 5 minutes, send 2 requests.
  3. Else if the hot water valve position uHeaCoi_actual is greater than 95%, send 1 request until the uHeaCoi_actual is less than 85%.
  4. Else if the hot water valve position uHeaCoi_actual is less than 95%, send 0 request.

If there is a hot-water coil and heating hot-water plant, heating hot-water plant reqeusts yHotWatPlaReq

Send the heating hot-water plant that serves the air handling unit a heating hot-water plant request as follows:

  1. If the hot water valve position uHeaCoi_actual is greater than 95%, send 1 request until the hot water valve position is less than 10%.
  2. If the hot water valve position uHeaCoi_actual is less than 95%, send 0 requests.

Parameters

TypeNameDefaultDescription
Booleanhave_hotWatCoitrueTrue: the AHU has hot water coil
Advanced
RealThys0.1Hysteresis for checking temperature difference
RealposHys0.05Hysteresis for checking valve position difference

Connectors

TypeNameDescription
input RealInputTAirSupMeasured supply air temperature [K]
input RealInputTAirSupSetSetpoint for supply air temperature [K]
input RealInputuCooCoi_actualActual cooling coil valve position [1]
input RealInputuHeaCoi_actualActual heating coil valve position [1]
output IntegerOutputyChiWatResReqChilled water reset request
output IntegerOutputyChiPlaReqChiller plant request
output IntegerOutputyHotWatResReqHot water reset request
output IntegerOutputyHotWatPlaReqHot water plant request

Modelica definition

block PlantRequests "Output plant requests for multizone air handling unit" parameter Boolean have_hotWatCoi = true "True: the AHU has hot water coil"; parameter Real Thys = 0.1 "Hysteresis for checking temperature difference"; parameter Real posHys = 0.05 "Hysteresis for checking valve position difference"; Buildings.Controls.OBC.CDL.Interfaces.RealInput TAirSup( final unit="K", final displayUnit="degC", final quantity="ThermodynamicTemperature") "Measured supply air temperature"; Buildings.Controls.OBC.CDL.Interfaces.RealInput TAirSupSet( final unit="K", final displayUnit="degC", final quantity="ThermodynamicTemperature") "Setpoint for supply air temperature"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uCooCoi_actual( final unit="1", final min=0, final max=1) "Actual cooling coil valve position"; Buildings.Controls.OBC.CDL.Interfaces.RealInput uHeaCoi_actual( final unit="1", final min=0, final max=1) if have_hotWatCoi "Actual heating coil valve position"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yChiWatResReq "Chilled water reset request"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yChiPlaReq "Chiller plant request"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yHotWatResReq if have_hotWatCoi "Hot water reset request"; Buildings.Controls.OBC.CDL.Interfaces.IntegerOutput yHotWatPlaReq if have_hotWatCoi "Hot water plant request"; protected Buildings.Controls.OBC.CDL.Reals.Subtract cooSupTemDif "Find the cooling supply temperature difference to the setpoint"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr( final t=3, final h=Thys) "Check if the supply temperature is greater than the setpoint by a threshold value"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr1( final t=2, final h=Thys) "Check if the supply temperature is greater than the setpoint by a threshold value"; Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel( final delayTime=120) "Check if the input has been true for a certain time"; Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel1( final delayTime=120) "Check if the input has been true for a certain time"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr2( final t=0.95, final h=posHys) "Check if the chilled water valve position is greater than a threshold value"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant thr( final k=3) "Constant 3"; Buildings.Controls.OBC.CDL.Integers.Switch chiWatRes3 "Send 3 chilled water reset request"; Buildings.Controls.OBC.CDL.Integers.Switch chiWatRes2 "Send 2 chilled water reset request"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant two( final k=2) "Constant 2"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr( final t=0.85, final h=posHys) "Check if the chilled water valve position is less than a threshold value"; Buildings.Controls.OBC.CDL.Logical.Latch lat "Keep true signal until other condition becomes true"; Buildings.Controls.OBC.CDL.Integers.Switch chiWatRes1 "Send 1 chilled water reset request"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant one( final k=1) "Constant 1"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant zer( final k=0) "Constant 0"; Buildings.Controls.OBC.CDL.Logical.Latch lat1 "Keep true signal until other condition becomes true"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr1( final t=0.1, final h=posHys) "Check if the chilled water valve position is less than a threshold value"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi3 "Send 1 chiller plant request"; Buildings.Controls.OBC.CDL.Reals.Subtract heaSupTemDif if have_hotWatCoi "Find the heating supply temperature difference to the setpoint"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr3( final t=17, final h=Thys) if have_hotWatCoi "Check if the supply temperature is less than the setpoint by a threshold value"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr4( final t=8, final h=Thys) if have_hotWatCoi "Check if the supply temperature is less than the setpoint by a threshold value"; Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel2( final delayTime=300) if have_hotWatCoi "Check if the input has been true for a certain time"; Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel3( final delayTime=300) if have_hotWatCoi "Check if the input has been true for a certain time"; Buildings.Controls.OBC.CDL.Integers.Switch hotWatRes3 if have_hotWatCoi "Send 3 hot water reset request"; Buildings.Controls.OBC.CDL.Integers.Switch hotWatRes2 if have_hotWatCoi "Send 2 hot water reset request"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr2( final t=0.85, final h=posHys) if have_hotWatCoi "Check if the hot water valve position is less than a threshold value"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr5( final t=0.95, final h=posHys) if have_hotWatCoi "Check if the hot water valve position is greater than a threshold value"; Buildings.Controls.OBC.CDL.Logical.Latch lat2 if have_hotWatCoi "Keep true signal until other condition becomes true"; Buildings.Controls.OBC.CDL.Integers.Switch hotWatRes1 if have_hotWatCoi "Send 1 hot water reset request"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr3( final t=0.1, final h=posHys) if have_hotWatCoi "Check if the hot water valve position is less than a threshold value"; Buildings.Controls.OBC.CDL.Logical.Latch lat3 if have_hotWatCoi "Keep true signal until other condition becomes true"; Buildings.Controls.OBC.CDL.Integers.Switch intSwi1 if have_hotWatCoi "Send 1 hot water plant request"; equation connect(TAirSup, cooSupTemDif.u1); connect(TAirSupSet, cooSupTemDif.u2); connect(cooSupTemDif.y, greThr.u); connect(greThr.y, truDel.u); connect(greThr1.y, truDel1.u); connect(cooSupTemDif.y, greThr1.u); connect(uCooCoi_actual, greThr2.u); connect(truDel.y, chiWatRes3.u2); connect(thr.y, chiWatRes3.u1); connect(truDel1.y, chiWatRes2.u2); connect(two.y, chiWatRes2.u1); connect(greThr2.y, lat.u); connect(uCooCoi_actual, lesThr.u); connect(lesThr.y, lat.clr); connect(one.y, chiWatRes1.u1); connect(lat.y, chiWatRes1.u2); connect(chiWatRes1.y, chiWatRes2.u3); connect(chiWatRes2.y, chiWatRes3.u3); connect(zer.y, chiWatRes1.u3); connect(chiWatRes3.y, yChiWatResReq); connect(greThr2.y, lat1.u); connect(uCooCoi_actual, lesThr1.u); connect(lesThr1.y, lat1.clr); connect(lat1.y, intSwi3.u2); connect(one.y, intSwi3.u1); connect(zer.y, intSwi3.u3); connect(intSwi3.y, yChiPlaReq); connect(TAirSupSet, heaSupTemDif.u1); connect(TAirSup, heaSupTemDif.u2); connect(greThr3.y, truDel2.u); connect(greThr4.y, truDel3.u); connect(heaSupTemDif.y, greThr3.u); connect(heaSupTemDif.y, greThr4.u); connect(truDel2.y, hotWatRes3.u2); connect(thr.y, hotWatRes3.u1); connect(hotWatRes2.y, hotWatRes3.u3); connect(two.y, hotWatRes2.u1); connect(truDel3.y, hotWatRes2.u2); connect(hotWatRes3.y, yHotWatResReq); connect(uHeaCoi_actual, greThr5.u); connect(greThr5.y, lat2.u); connect(uHeaCoi_actual, lesThr2.u); connect(lesThr2.y, lat2.clr); connect(lat2.y, hotWatRes1.u2); connect(one.y, hotWatRes1.u1); connect(zer.y, hotWatRes1.u3); connect(hotWatRes1.y, hotWatRes2.u3); connect(uHeaCoi_actual, lesThr3.u); connect(lesThr3.y, lat3.clr); connect(greThr5.y, lat3.u); connect(lat3.y, intSwi1.u2); connect(one.y, intSwi1.u1); connect(zer.y, intSwi1.u3); connect(intSwi1.y, yHotWatPlaReq); end PlantRequests;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefDamper Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefDamper

Relief damper control for AHUs using actuated dampers without fan

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefDamper

Information

Sequence for controlling actuated relief damper yRelDam for AHUs using actuated relief damper without a fan. It is implemented according to Section 5.16.8 of ASHRAE Guideline G36, May 2020.

Parameters

TypeNameDefaultDescription
RealdpBuiSet12Building static pressure difference relative to ambient (positive to pressurize the building) [Pa]
Realk0.5Gain, applied to building pressure control error normalized with dpBuiSet [1]

Connectors

TypeNameDescription
input RealInputdpBuiBuilding static pressure difference, relative to ambient (positive if pressurized) [Pa]
input BooleanInputu1SupFanSupply fan status
output RealOutputyRelDamRelief damper commanded position [1]

Modelica definition

block ReliefDamper "Relief damper control for AHUs using actuated dampers without fan" parameter Real dpBuiSet( final unit="Pa", final quantity="PressureDifference", max=30) = 12 "Building static pressure difference relative to ambient (positive to pressurize the building)"; parameter Real k(min=0, unit="1") = 0.5 "Gain, applied to building pressure control error normalized with dpBuiSet"; Buildings.Controls.OBC.CDL.Interfaces.RealInput dpBui( final unit="Pa", displayUnit="Pa") "Building static pressure difference, relative to ambient (positive if pressurized)"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "Supply fan status"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRelDam( final unit="1", final min=0, final max=1) "Relief damper commanded position"; protected Buildings.Controls.OBC.CDL.Reals.Switch swi "Check if relief damper should be enabled"; Buildings.Controls.OBC.CDL.Reals.Subtract conErr( u1(final unit="Pa", displayUnit="Pa"), u2(final unit="Pa", displayUnit="Pa"), y(final unit="Pa", displayUnit="Pa")) "Control error"; Buildings.Controls.OBC.CDL.Reals.PID conP( final controllerType=Buildings.Controls.OBC.CDL.Types.SimpleController.P, final k=k, final reverseActing=false) "Building static pressure controller"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zerDam( final k=0) "Close damper when disabled"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant dpBuiSetPoi( final k=dpBuiSet) "Building pressure setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zer( final k=0) "Zero constant"; equation connect(u1SupFan, swi.u2); connect(dpBuiSetPoi.y, conErr.u2); connect(conErr.y, conP.u_m); connect(zer.y, conP.u_s); connect(conP.y, swi.u1); connect(zerDam.y, swi.u3); connect(dpBui, conErr.u1); connect(swi.y, yRelDam); end ReliefDamper;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFan Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFan

Sequence for control of relief fan in AHU

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFan

Information

Sequence for controling relief fan that is part of AHU. It is developed based on Section 5.16.9 of ASHRAE Guideline 36, May 2020, with the modification to accommodate the single relief fan control.

  1. The relief fan shall be enabled when the AHU supply fan is proven ON (u1SupFan=true), and shall be disabled otherwise.
  2. Building static pressure (dpBui) shall be time averaged with a sliding 5-minute window and 15 second sampling rate (to dampen fluctuations). The average value shall be that displayed and used for control.
  3. A P-only control loop maintains the building pressure at a set point (dpBuiSet) of 12 Pa (0.05 in. of water) with an output ranging from 0% to 100%. The loop is disabled and output set to zero when the relief fan is disabled.
  4. Fan speed shall be equal to the PID signal but no less than the minimum speed.
    1. When relief system is enabled, and the control loop output is above 5%, open the motorized dampers to the relief fans; close the dampers when the loop output drops to 0% for 5 minutes.
    2. When the control loop output is above minimum speed (relFanSpe_min) plus 15% by 7 minutes, start the relief fan.
    3. When the control loop output is below minimum speed (relFanSpe_min) by 5 minutes, shut off the relief fan.

Parameters

TypeNameDefaultDescription
RealrelFanSpe_min0.1Relief fan minimum speed
RealdpBuiSet12Building static pressure difference relative to ambient (positive to pressurize the building) [Pa]
Pressure controller
Realk1Gain, normalized using dpBuiSet [1]
Advanced
Realhys0.005Hysteresis for checking the controller output value

Connectors

TypeNameDescription
input RealInputdpBuiBuilding static pressure difference, relative to ambient (positive if pressurized)
input BooleanInputu1SupFanAHU supply fan proven on status
output RealOutputyDpBuiBuilding static pressure difference, relative to ambient (positive if pressurized)
output RealOutputyDamDamper commanded position [1]
output RealOutputyRelFanRelief fan commanded speed [1]
output BooleanOutputy1RelFanRelief fan commanded on

Modelica definition

block ReliefFan "Sequence for control of relief fan in AHU" parameter Real relFanSpe_min( final min=0, final max=1)= 0.1 "Relief fan minimum speed"; parameter Real dpBuiSet( final unit="Pa", final quantity="PressureDifference", final max=30) = 12 "Building static pressure difference relative to ambient (positive to pressurize the building)"; parameter Real k( final unit="1") = 1 "Gain, normalized using dpBuiSet"; parameter Real hys = 0.005 "Hysteresis for checking the controller output value"; Buildings.Controls.OBC.CDL.Interfaces.RealInput dpBui( displayUnit="Pa", final quantity="PressureDifference") "Building static pressure difference, relative to ambient (positive if pressurized)"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "AHU supply fan proven on status"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDpBui( displayUnit="Pa", final quantity="PressureDifference") "Building static pressure difference, relative to ambient (positive if pressurized)"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDam( final unit="1", final min=0, final max=1) "Damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRelFan( final unit="1", final max=1) "Relief fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1RelFan "Relief fan commanded on"; Buildings.Controls.OBC.CDL.Reals.MovingAverage movMea( final delta=300) "Average building static pressure measurement"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant dpBuiSetPoi( final k=dpBuiSet) "Building pressure setpoint"; Buildings.Controls.OBC.CDL.Reals.Divide div1 "Normalized the control error"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant conOne( final k=1) "Constant one"; Buildings.Controls.OBC.CDL.Reals.PID conP( final controllerType=Buildings.Controls.OBC.CDL.Types.SimpleController.P, final k=k, final reverseActing=false) "Building static pressure controller"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr( final t=0.05, final h=hys) "Check if the controller output is greater than threshold"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr( final t=0.005, final h=hys) "Check if the controller output is near zero"; Buildings.Controls.OBC.CDL.Logical.Timer tim( final t=300) "Check if the controller output has been near zero for threshold time"; Buildings.Controls.OBC.CDL.Logical.And and2 "Check if the controller output is greater than threshold and the relief system has been enabled"; Buildings.Controls.OBC.CDL.Logical.Latch lat "Enable damper"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr2( final t=relFanSpe_min + 0.15, final h=hys) "Check if the controller output is greater than minimum speed plus threshold"; Buildings.Controls.OBC.CDL.Logical.Timer upTim( final t=420) "Check if the controller output has been greater than threshold for sufficient long time"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr3( final t=relFanSpe_min, final h=hys) "Check if the controller output is less than minimum speed"; Buildings.Controls.OBC.CDL.Logical.Timer dowTim( final t=300) "Check if the controller output has been less than threshold for sufficient long time"; Buildings.Controls.OBC.CDL.Logical.Latch lat1 "Stage down lag fan"; Buildings.Controls.OBC.CDL.Logical.Or relDam "Open relief damper"; Buildings.Controls.OBC.CDL.Logical.And relFan "Turn on relief fan"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea2 "Convert boolean to real"; Buildings.Controls.OBC.CDL.Reals.Multiply pro1 "Relief fan speed"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea1 "Convert boolean to real"; equation connect(dpBui, movMea.u); connect(dpBuiSetPoi.y, div1.u2); connect(movMea.y, div1.u1); connect(div1.y, conP.u_m); connect(conOne.y, conP.u_s); connect(conP.y, greThr.u); connect(greThr.y, and2.u1); connect(conP.y, lesThr.u); connect(lesThr.y, tim.u); connect(tim.passed, lat.clr); connect(and2.y, lat.u); connect(u1SupFan, and2.u2); connect(conP.y, greThr2.u); connect(greThr2.y, upTim.u); connect(conP.y, lesThr3.u); connect(lesThr3.y, dowTim.u); connect(upTim.passed, lat1.u); connect(dowTim.passed, lat1.clr); connect(lat.y, relDam.u1); connect(u1SupFan, relFan.u1); connect(lat1.y, relFan.u2); connect(relFan.y, relDam.u2); connect(relFan.y, booToRea2.u); connect(booToRea2.y, pro1.u2); connect(conP.y, pro1.u1); connect(movMea.y, yDpBui); connect(relDam.y, booToRea1.u); connect(booToRea1.y, yDam); connect(pro1.y, yRelFan); connect(relFan.y, y1RelFan); end ReliefFan;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFanGroup Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFanGroup

Sequence for controlling relief fan group

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReliefFanGroup

Information

Sequence for controlling group of relief fans and their dampers for AHUs using actuated relief dampers with relief fan(s). It is developed based on Section 5.16.9 of ASHRAE Guideline 36, May 2020.

  1. All operating relief fans that serve a common or shared air volume shall be grouped and controlled as if they were one system, running at the same speed and using the same control loop, even if they are associated with different AHUs.
  2. A relief fan shall be enabled when its associated supply fan is proven ON (u1SupFan=true), and shall be disabled otherwise.
  3. Building static pressure (dpBui) shall be time averaged with a sliding 5-minute window and 15 second sampling rate (to dampen fluctuations). The average value shall be that displayed and used for control.
  4. A P-only control loop maintains the building pressure at a set point (dpBuiSet) of 12 Pa (0.05 in. of water) with an output ranging from 0% to 100%. The loop is disabled and output set to zero when all fans in the relief system group are disabled.
  5. Fan speed signal to all operating fans in the relief system group shall be the same and shall be equal to the PID signal but no less than the minimum speed. Except for Stage 0, discharge dampers of all relief fans shall be open only when fan is commanded ON.
    1. Stage 0 (barometric relief). When relief system is enabled, and the control loop output is above 5%, open the motorized dampers to all relief fans serving the relief system group that are enabled; close the dampers when the loop output drops to 0% for 5 minutes.
    2. Stage Up. When control loop output is above minimum speed (relFanSpe_min) plus 15%, start stage-up timer. Each time the timer reaches 7 minutes, start the next relief fan (and open the associated damper) in the relief system group, per staging order, and reset the timer to 0. The timer is reset to 0 and frozen if control loop is below minimum speed plus 15%. Note, when staging from Stage 0 (no relief fans) to Stage 1 (one relief fan), the discharge dampers of all nonoperating relief fans must be closed.
    3. Stage Down. When PID loop is below minimum speed (relFanSpe_min), start stage-down timer. Each time the timer reaches 5 minutes, shut off lag fan per staging order and reset the timer to 0. The timer is reset to 0 and frozen if PID loop rises above minimum speed or all fans are OFF. If all fans are OFF, go to Stage 0 (all dampers open and all fans OFF).
  6. For fans in a Level 2 alarm and status is OFF, discharge damper shall be closed when is above Stage 0.

Parameters

TypeNameDefaultDescription
IntegernSupFan2Total number of AHU supply fans that are serving the same common space
IntegernRelFan4Total number of relief fans that are serving the same common space
RealrelFanSpe_min0.1Relief fan minimum speed
IntegerstaVec[nRelFan]{2,3,1,4}Vector of the order for staging up relief fan, i.e. the 1st element means the 1st relief fan and its value showing its sequence when staging up
IntegerrelFanMat[nRelFan, nSupFan]{{1,0},{1,0},{0,1},{0,1}}Relief fan matrix with relief fan as row index and AHU supply fan as column index. It flags which relief fan is associated with which supply fan
RealdpBuiSet12Building static pressure difference relative to ambient (positive to pressurize the building) [Pa]
Pressure controller
Realk1Gain, normalized using dpBuiSet [1]
Advanced
Realhys0.005Hysteresis for checking the controller output value

Connectors

TypeNameDescription
input BooleanInputu1SupFan[nSupFan]AHU supply fan proven on status
input RealInputdpBuiBuilding static pressure difference, relative to ambient (positive if pressurized)
input IntegerInputuRelFanAla[nRelFan]Relief fan current alarm index
input BooleanInputu1RelFan[nRelFan]Relief fan proven on status
output RealOutputyDpBuiBuilding static pressure difference, relative to ambient (positive if pressurized)
output RealOutputyRelFan[nRelFan]Relief fan commanded speed [1]
output RealOutputyDam[nRelFan]Damper commanded position [1]

Modelica definition

block ReliefFanGroup "Sequence for controlling relief fan group" parameter Integer nSupFan = 2 "Total number of AHU supply fans that are serving the same common space"; parameter Integer nRelFan = 4 "Total number of relief fans that are serving the same common space"; parameter Real relFanSpe_min( final min=0, final max=1)= 0.1 "Relief fan minimum speed"; parameter Integer staVec[nRelFan] = {2,3,1,4} "Vector of the order for staging up relief fan, i.e. the 1st element means the 1st relief fan and its value showing its sequence when staging up"; parameter Integer relFanMat[nRelFan, nSupFan] = {{1,0},{1,0},{0,1},{0,1}} "Relief fan matrix with relief fan as row index and AHU supply fan as column index. It flags which relief fan is associated with which supply fan"; parameter Real dpBuiSet( final unit="Pa", final quantity="PressureDifference", final max=30) = 12 "Building static pressure difference relative to ambient (positive to pressurize the building)"; parameter Real k( final unit="1") = 1 "Gain, normalized using dpBuiSet"; parameter Real hys = 0.005 "Hysteresis for checking the controller output value"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan[nSupFan] "AHU supply fan proven on status"; Buildings.Controls.OBC.CDL.Interfaces.RealInput dpBui( displayUnit="Pa", final quantity="PressureDifference") "Building static pressure difference, relative to ambient (positive if pressurized)"; Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uRelFanAla[nRelFan] "Relief fan current alarm index"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1RelFan[nRelFan] "Relief fan proven on status"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDpBui( displayUnit="Pa", final quantity="PressureDifference") "Building static pressure difference, relative to ambient (positive if pressurized)"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRelFan[nRelFan]( final unit=fill("1", nRelFan), final max=fill(1, nRelFan)) "Relief fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDam[nRelFan]( final unit=fill("1",nRelFan), final min=fill(0,nRelFan), final max=fill(1,nRelFan)) "Damper commanded position"; Buildings.Controls.OBC.CDL.Reals.MatrixGain enaRel( final K=relFanMat) "Vector of relief fans with the enabled one denoted by 1"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea[nSupFan] "Convert boolean to real"; Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter gai[nRelFan]( final k=staVec) "Vector of enabling fan, along with its staging order"; Buildings.Controls.OBC.CDL.Reals.MovingAverage movMea( final delta=300) "Average building static pressure measurement"; Buildings.Controls.OBC.CDL.Reals.Divide div1 "Normalized the control error"; Buildings.Controls.OBC.CDL.Reals.PID conP( final controllerType=Buildings.Controls.OBC.CDL.Types.SimpleController.P, final k=k, final reverseActing=false) "Building static pressure controller"; Buildings.Controls.OBC.CDL.Logical.MultiOr enaRelGro( final nin=nSupFan) "Relief group enabling status"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea1 "Convert boolean to real"; Buildings.Controls.OBC.CDL.Reals.Multiply pro "Set controller output to zero when the relief system is disabled"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr( final t=0.05, final h=hys) "Check if the controller output is greater than threshold"; Buildings.Controls.OBC.CDL.Logical.And and2 "Check if the controller output is greater than threshold and the relief system has been enabled"; Buildings.Controls.OBC.CDL.Logical.Latch lat "Enable damper"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr( final t=0.005, final h=hys) "Check if the controller output is near zero"; Buildings.Controls.OBC.CDL.Logical.Timer tim( final t=300) "Check if the controller output has been near zero for threshold time"; Buildings.Controls.OBC.CDL.Routing.BooleanScalarReplicator booRep( final nout=nRelFan) "Boolean replicator"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr1[nRelFan]( final t=fill(0.5, nRelFan)) "Check if a relief fan should be enabled"; Buildings.Controls.OBC.CDL.Logical.And enaDam[nRelFan] "Enable damper"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr2( final t=relFanSpe_min + 0.15, final h=hys) "Check if the controller output is greater than minimum speed plus threshold"; Buildings.Controls.OBC.CDL.Logical.Timer upTim( final t=420) "Check if the controller output has been greater than threshold for sufficient long time"; Buildings.Controls.OBC.CDL.Logical.Pre pre( final pre_u_start=true) "Break algebraic loop"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea2[nRelFan] "Convert boolean to real"; Buildings.Controls.OBC.CDL.Reals.Subtract sub2[nRelFan] "Identify relief fans that have been enabled but not yet operating"; Buildings.Controls.OBC.CDL.Reals.Multiply pro1[nRelFan] "List of standby fans, along with their staging order"; Buildings.Controls.OBC.CDL.Reals.MultiMin mulMin(nin=nRelFan) "Identify current order of staging"; Buildings.Controls.OBC.CDL.Routing.RealScalarReplicator reaRep( final nout=nRelFan) "Replicate real number"; Buildings.Controls.OBC.CDL.Reals.Subtract sub1[nRelFan] "Identify next operating fan"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr1[nRelFan]( final t=fill(0.5, nRelFan)) "Check if the input is less than threshold"; Buildings.Controls.OBC.CDL.Reals.AddParameter addPar[nRelFan]( final p=fill(nRelFan + 1, nRelFan)) "Add value to the input"; Buildings.Controls.OBC.CDL.Reals.Switch swi[nRelFan] "Switch input values"; Buildings.Controls.OBC.CDL.Reals.Abs abs1[nRelFan] "Find absolute value"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr2[nRelFan]( final t=fill(0.5, nRelFan)) "Identify next operating fan"; Buildings.Controls.OBC.CDL.Logical.Or or2[nRelFan] "Targeted vector of operating relief fan after one new fan being turned on"; Buildings.Controls.OBC.CDL.Logical.Latch lat2 "Stage up next relief fan"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr3( final t=relFanSpe_min, final h=hys) "Check if the controller output is less than minimum speed"; Buildings.Controls.OBC.CDL.Logical.Timer dowTim( final t=300) "Check if the controller output has been less than threshold for sufficient long time"; Buildings.Controls.OBC.CDL.Logical.Pre pre1( final pre_u_start=true) "Break algebraic loop"; Buildings.Controls.OBC.CDL.Reals.Multiply pro2[nRelFan] "List of operating fans, along with their staging order"; Buildings.Controls.OBC.CDL.Reals.AddParameter addPar1[nRelFan]( final p=fill(nRelFan + 1, nRelFan)) "Add value to the input"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr4[nRelFan]( final t=fill(0.5, nRelFan)) "Check if the input is less than threshold"; Buildings.Controls.OBC.CDL.Reals.Switch swi1[nRelFan] "Switch input values"; Buildings.Controls.OBC.CDL.Reals.MultiMin mulMin1( final nin=nRelFan) "Minimum staging order of the running relief fans"; Buildings.Controls.OBC.CDL.Reals.Subtract sub3[nRelFan] "Identify next operating fan"; Buildings.Controls.OBC.CDL.Reals.Abs abs2[nRelFan] "Find absolute value"; Buildings.Controls.OBC.CDL.Reals.LessThreshold lesThr5[nRelFan]( final t=fill(0.5, nRelFan)) "Identify next fan to be off"; Buildings.Controls.OBC.CDL.Routing.RealScalarReplicator reaRep1( final nout=nRelFan) "Replicate real number"; Buildings.Controls.OBC.CDL.Logical.Xor xor[nRelFan] "Vector of relief fan after one fan being turned off"; Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt[nRelFan] "Convert boolean to integer"; Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt1[nRelFan] "Convert boolean to integer"; Buildings.Controls.OBC.CDL.Conversions.BooleanToInteger booToInt2[nRelFan] "Convert boolean to integer"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu[nRelFan] "Check if newly started fan has become proven on"; Buildings.Controls.OBC.CDL.Logical.MultiAnd mulAnd( final nin=nRelFan) "Check if newly started fan has become proven on"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu1[nRelFan] "Check if newly turned off fan has become off"; Buildings.Controls.OBC.CDL.Logical.MultiAnd mulAnd2( final nin=nRelFan) "Check if newly turned off fan has become off"; Buildings.Controls.OBC.CDL.Logical.Latch lat1 "Stage down lag fan"; Buildings.Controls.OBC.CDL.Logical.Switch logSwi[nRelFan] "Vector of relief fan status after staging up"; Buildings.Controls.OBC.CDL.Routing.BooleanScalarReplicator booRep1( final nout=nRelFan) "Replicate boolean input"; Buildings.Controls.OBC.CDL.Logical.Switch logSwi1[nRelFan] "Vector of relief fan status after staging down"; Buildings.Controls.OBC.CDL.Routing.BooleanScalarReplicator booRep2( final nout=nRelFan) "Replicate boolean input"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea3[nRelFan] "Convert boolean to real"; Buildings.Controls.OBC.CDL.Reals.Limiter lim( final uMax=1, final uMin=relFanSpe_min) "Limit the controller output"; Buildings.Controls.OBC.CDL.Routing.RealScalarReplicator reaRep2( final nout=nRelFan) "Replicate real input"; Buildings.Controls.OBC.CDL.Reals.Multiply pro3[nRelFan] "Relief fan speed"; Buildings.Controls.OBC.CDL.Logical.Switch logSwi2[nRelFan] "Vector of relief fan status after staging up"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant dpBuiSetPoi( final k=dpBuiSet) "Building pressure setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant conOne( final k=1) "Constant one"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant con( final k=0) "Zero fan speed when it is in stage 0"; Buildings.Controls.OBC.CDL.Reals.Switch swi2 "Switch input values"; Buildings.Controls.OBC.CDL.Logical.MultiOr mulOr(nin=nRelFan) "Check if there is any relief fan enabled, but may not be running"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea4[nRelFan] "Convert boolean to real"; Buildings.Controls.OBC.CDL.Logical.Not not1 "Logical not"; Buildings.Controls.OBC.CDL.Logical.And and1 "Start timer, and reset to zero if the threshold time has passed"; Buildings.Controls.OBC.CDL.Logical.And and3 "Start timer, and reset to zero if the threshold time has passed"; Buildings.Controls.OBC.CDL.Logical.Not not2 "Logical not"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu2[nRelFan] "Check if the relief fan is in level 2 alarm"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt[nRelFan]( final k=fill(2, nRelFan)) "Constant"; Buildings.Controls.OBC.CDL.Logical.Not not3[nRelFan] "Logical not"; Buildings.Controls.OBC.CDL.Logical.And and4[nRelFan] "Check if the relief fan is in level 2 alarm and it is proven off"; Buildings.Controls.OBC.CDL.Conversions.BooleanToReal booToRea5[nRelFan]( final realTrue=fill(0, nRelFan), final realFalse=fill(1, nRelFan)) "Convert boolean to real"; Buildings.Controls.OBC.CDL.Reals.Multiply mul[nRelFan] "Product of inputs"; Buildings.Controls.OBC.CDL.Reals.GreaterThreshold greThr3[nRelFan]( final t=fill(0.5, nRelFan)) "Check if the relief fan is enabled"; Buildings.Controls.OBC.CDL.Logical.MultiAnd mulAnd1( final nin=nRelFan) "Check if all the fans are proven off"; Buildings.Controls.OBC.CDL.Reals.Switch swi3[nRelFan] "Switch input values"; Buildings.Controls.OBC.CDL.Routing.BooleanScalarReplicator booRep4( final nout=nRelFan) "Replicate boolean input"; Buildings.Controls.OBC.CDL.Logical.Switch logSwi3[nRelFan] "Vector of relief fan status after staging down"; Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel[nRelFan]( final delayTime=fill(2, nRelFan)) "Delay true input"; Buildings.Controls.OBC.CDL.Logical.MultiOr mulOr1( final nin=nRelFan) "Check if there is any fan is proven on"; Buildings.Controls.OBC.CDL.Routing.BooleanScalarReplicator booRep5( final nout=nRelFan) "Replicate boolean input"; Buildings.Controls.OBC.CDL.Logical.Not not5[nRelFan] "Logical not"; Buildings.Controls.OBC.CDL.Logical.Not not6[nRelFan] "Logical not"; Buildings.Controls.OBC.CDL.Logical.TrueDelay truDel1[nRelFan]( final delayTime=fill(2, nRelFan)) "Delay true input"; equation connect(u1SupFan, booToRea.u); connect(enaRel.u, booToRea.y); connect(enaRel.y, gai.u); connect(dpBui, movMea.u); connect(conOne.y, conP.u_s); connect(movMea.y, div1.u1); connect(dpBuiSetPoi.y, div1.u2); connect(div1.y, conP.u_m); connect(u1SupFan, enaRelGro.u); connect(booToRea1.y, pro.u1); connect(enaRelGro.y, booToRea1.u); connect(conP.y, greThr.u); connect(enaRelGro.y, and2.u2); connect(greThr.y, and2.u1); connect(and2.y, lat.u); connect(conP.y, lesThr.u); connect(lesThr.y, tim.u); connect(tim.passed, lat.clr); connect(lat.y, booRep.u); connect(gai.y, greThr1.u); connect(greThr1.y, enaDam.u1); connect(booRep.y, enaDam.u2); connect(u1RelFan, booToRea2.u); connect(enaRel.y, sub2.u1); connect(booToRea2.y, sub2.u2); connect(gai.y, pro1.u1); connect(sub2.y, pro1.u2); connect(mulMin.y, reaRep.u); connect(lesThr1.y, swi.u2); connect(pro1.y, swi.u3); connect(pro1.y, addPar.u); connect(addPar.y, swi.u1); connect(gai.y, sub1.u1); connect(reaRep.y, sub1.u2); connect(sub1.y, abs1.u); connect(abs1.y, lesThr2.u); connect(lesThr2.y, or2.u1); connect(booToRea2.y, pro2.u2); connect(gai.y, pro2.u1); connect(pro2.y, addPar1.u); connect(pro2.y, lesThr4.u); connect(lesThr4.y, swi1.u2); connect(addPar1.y, swi1.u1); connect(pro2.y, swi1.u3); connect(swi1.y, mulMin1.u); connect(mulMin1.y, reaRep1.u); connect(reaRep1.y, sub3.u2); connect(gai.y, sub3.u1); connect(sub3.y, abs2.u); connect(abs2.y, lesThr5.u); connect(lesThr5.y, xor.u1); connect(booToInt.y, intEqu.u1); connect(booToInt1.y, intEqu.u2); connect(intEqu.y, mulAnd.u); connect(booToInt1.y, intEqu1.u1); connect(booToInt2.y, intEqu1.u2); connect(intEqu1.y, mulAnd2.u); connect(lat2.y, booRep1.u); connect(lat1.y, booRep2.u); connect(booRep2.y, logSwi1.u2); connect(mulAnd2.y, lat1.clr); connect(conP.y, lesThr3.u); connect(xor.y, logSwi1.u1); connect(conP.y, greThr2.u); connect(booRep1.y, logSwi.u2); connect(or2.y, logSwi.u1); connect(u1RelFan, xor.u2); connect(u1RelFan, logSwi1.u3); connect(u1RelFan, booToInt1.u); connect(u1RelFan, or2.u2); connect(logSwi.y, booToRea3.u); connect(conP.y, lim.u); connect(lim.y, pro.u2); connect(booToRea3.y, pro3.u2); connect(pro3.y, yRelFan); connect(reaRep2.y, pro3.u1); connect(con.y, swi2.u3); connect(mulOr.y, swi2.u2); connect(movMea.y, yDpBui); connect(logSwi2.y, booToRea4.u); connect(not1.y, pre.u); connect(and1.y, upTim.u); connect(greThr2.y, and1.u1); connect(not2.y, pre1.u); connect(lesThr3.y, and3.u1); connect(and3.y, dowTim.u); connect(uRelFanAla, intEqu2.u1); connect(conInt.y, intEqu2.u2); connect(u1RelFan, not3.u); connect(intEqu2.y, and4.u1); connect(not3.y, and4.u2); connect(and4.y, booToRea5.u); connect(booToRea4.y, mul.u1); connect(booToRea5.y, mul.u2); connect(mul.y, yDam); connect(enaDam.y, logSwi2.u3); connect(logSwi.y, logSwi2.u1); connect(upTim.passed, not1.u); connect(upTim.passed, lat2.u); connect(dowTim.passed, not2.u); connect(dowTim.passed, lat1.u); connect(enaRel.y, greThr3.u); connect(greThr3.y, mulOr.u); connect(pro.y, swi2.u1); connect(swi2.y, reaRep2.u); connect(pro1.y, lesThr1.u); connect(not3.y, mulAnd1.u); connect(mulAnd1.y, booRep4.u); connect(booRep4.y, swi3.u2); connect(pro1.y, swi3.u1); connect(swi.y, swi3.u3); connect(swi3.y, mulMin.u); connect(pre1.y, and3.u2); connect(u1RelFan, logSwi3.u1); connect(booRep4.y, logSwi3.u2); connect(logSwi1.y, logSwi3.u3); connect(logSwi3.y, logSwi.u3); connect(pre.y, and1.u2); connect(truDel.y, booToInt.u); connect(or2.y, truDel.u); connect(mulAnd.y, lat2.clr); connect(logSwi.y, mulOr1.u); connect(mulOr1.y, booRep5.u); connect(booRep5.y, logSwi2.u2); connect(not6.y, booToInt2.u); connect(truDel1.y, not6.u); connect(not5.y, truDel1.u); connect(xor.y, not5.u); end ReliefFanGroup;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanAirflowTracking Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanAirflowTracking

Return fan control for AHUs using return fan with airflow tracking

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanAirflowTracking

Information

Sequence for controlling return fan yRetFan for AHUs using return fan with airflow tracking. It is implemented according to Section 5.16.11 of ASHRAE Guideline G36, May 2020.

Parameters

TypeNameDefaultDescription
RealdifFloSet Airflow differential between supply air and return air fans required to maintain building pressure at desired pressure [m3/s]
Fan controller
SimpleControllerconTypBuildings.Controls.OBC.CDL.T...Type of controller
Realk1Gain, normalized using dpBuiSet [1]
RealTi0.5Time constant of integrator block [s]
RealTd0.1Time constant of derivative block [s]
RealmaxSpe1Upper limit of output
RealminSpe0Lower limit of output

Connectors

TypeNameDescription
input RealInputVAirSup_flowMeasured AHU supply airflow rate [m3/s]
input RealInputVAirRet_flowMeasured AHU return airflow rate [m3/s]
input BooleanInputu1SupFanSupply fan status
output RealOutputyRetFanReturn fan commanded speed [1]
output BooleanOutputy1RetFanReturn fan commanded on

Modelica definition

block ReturnFanAirflowTracking "Return fan control for AHUs using return fan with airflow tracking" parameter Real difFloSet( final unit="m3/s", final quantity="VolumeFlowRate") "Airflow differential between supply air and return air fans required to maintain building pressure at desired pressure"; parameter Buildings.Controls.OBC.CDL.Types.SimpleController conTyp= Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller"; parameter Real k(final unit="1") = 1 "Gain, normalized using dpBuiSet"; parameter Real Ti( final unit="s", final quantity="Time")=0.5 "Time constant of integrator block"; parameter Real Td( final unit="s", final quantity="Time")=0.1 "Time constant of derivative block"; parameter Real maxSpe=1 "Upper limit of output"; parameter Real minSpe=0 "Lower limit of output"; Buildings.Controls.OBC.CDL.Interfaces.RealInput VAirSup_flow( final unit="m3/s", final min=0, final quantity="VolumeFlowRate") "Measured AHU supply airflow rate"; Buildings.Controls.OBC.CDL.Interfaces.RealInput VAirRet_flow( final unit="m3/s", final min=0, final quantity="VolumeFlowRate") "Measured AHU return airflow rate"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "Supply fan status"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRetFan( final unit="1", final min=0, final max=1) "Return fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1RetFan "Return fan commanded on"; Buildings.Controls.OBC.CDL.Reals.PID conP( final controllerType=conTyp, final k=k, final Ti=Ti, final Td=Td, final yMax=maxSpe, final yMin=minSpe) "Building static pressure controller"; protected Buildings.Controls.OBC.CDL.Reals.Switch swi "Check if relief damper should be enabled"; Buildings.Controls.OBC.CDL.Reals.Subtract conErr( u1(final unit="m3/s", displayUnit="m3/s"), u2(final unit="m3/s", displayUnit="m3/s"), y(final unit="m3/s", displayUnit="m3/s")) "Control error"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zerSpe( final k=0) "Disable return fan"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant difFlo( final k=difFloSet) "Return airflow less than supply airflow"; equation connect(u1SupFan, swi.u2); connect(zerSpe.y, swi.u3); connect(swi.y,yRetFan); connect(VAirSup_flow, conErr.u1); connect(difFlo.y, conErr.u2); connect(conErr.y, conP.u_s); connect(VAirRet_flow, conP.u_m); connect(conP.y, swi.u1); connect(u1SupFan, y1RetFan); end ReturnFanAirflowTracking;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanDirectPressure Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanDirectPressure

Return fan control with direct building pressure control

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.ReturnFanDirectPressure

Information

Setpoint for return fan discharge pressure and relief air damper for a multi zone VAV AHU according to Section 5.16.10 of ASHRAE Guideline G36, May 2020.

Note that this sequence assumes that the AHU units with return fan having the return fan with direct building pressure control have the minimum outdoor air damper.

  1. Return fan operates whenever associated supply fan is proven on and is off otherwise.

  2. Return fan is controlled to maintain return fan discharge static pressure at setpoint dpBuiSet.

  3. Relief damper is only enabled when the associated supply and return fans are proven on (u1SupFan=true) and the minimum outdoor air damper is open (to be controlled in a separate sequence). The relief dampers is closed when the fan is disabled.

  4. The building static pressure is time averaged with a sliding 5-minute window to dampen fluctuations. The averaged value shall be displayed and is used for control.

  5. When the relief damper is enabled, a control loop modulates the relief damper in sequence with the return fan static pressure setpoint as shown in the figure below to maintain the building pressure equal to dpBuiSet, which is by default 12 Pa (0.05 inches).

The output signal of the building pressure control is as follows:

  1. From 0 to 0.5, the building pressure control loop modulates the exhaust dampers from yRelDam = 0 (closed) to yRelDam = 1 (open).
  2. From 0.5 to 1, the building pressure control loop resets the return fan discharge static pressure setpoint from p_rel_RetFan_min to p_rel_RetFan_max. The p_rel_RetFan_min and p_rel_RetFan_max are specified in Section 3.2.1.4.

Image of return fan control for multi zone AHU

Parameters

TypeNameDefaultDescription
RealdpBuiSet12Building static pressure difference relative to ambient (positive to pressurize the building) [Pa]
Realp_rel_RetFan_min2.4Return fan discharge static pressure difference minimum setpoint,no less than 2.4 Pa [Pa]
Realp_rel_RetFan_max40Return fan discharge static pressure maximum setpoint [Pa]
RealdisSpe_min Return fan speed when providing the minimum return fan discharge static pressure difference [1]
RealdisSpe_max Return fan speed when providing the maximum return fan discharge static pressure difference [1]
Pressure controller
SimpleControllerconTypBuildings.Controls.OBC.CDL.T...Type of controller
Realk1Gain, normalized using dpBuiSet [1]
RealTi0.5Time constant of integrator block [s]
RealTd0.1Time constant of derivative block [s]

Connectors

TypeNameDescription
input RealInputdpBuiBuilding static pressure difference, relative to ambient (positive if pressurized) [Pa]
input BooleanInputu1MinOutAirDamMinimum outdoor air damper status, true when it is open
input BooleanInputu1SupFanSupply fan status
output RealOutputyDpBuiAveraged building static pressure [Pa]
output RealOutputyRelDamRelief damper commanded position [1]
output RealOutputdpDisSetReturn fan discharge static pressure setpoint [Pa]
output RealOutputyRetFanReturn fan commanded speed [1]
output BooleanOutputy1RetFanReturn fan commanded on

Modelica definition

block ReturnFanDirectPressure "Return fan control with direct building pressure control" parameter Real dpBuiSet( final unit="Pa", final quantity="PressureDifference", final max=30) = 12 "Building static pressure difference relative to ambient (positive to pressurize the building)"; parameter Real p_rel_RetFan_min( final unit="Pa", final quantity="PressureDifference", final min=0, final max=1000) = 2.4 "Return fan discharge static pressure difference minimum setpoint,no less than 2.4 Pa"; parameter Real p_rel_RetFan_max( final unit="Pa", final quantity="PressureDifference", final min=0, final max=1000) = 40 "Return fan discharge static pressure maximum setpoint"; parameter Real disSpe_min( final unit="1", final min=0, final max=1) "Return fan speed when providing the minimum return fan discharge static pressure difference"; parameter Real disSpe_max( final unit="1", final min=0, final max=1) "Return fan speed when providing the maximum return fan discharge static pressure difference"; parameter Buildings.Controls.OBC.CDL.Types.SimpleController conTyp= Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller"; parameter Real k(final unit="1") = 1 "Gain, normalized using dpBuiSet"; parameter Real Ti( final unit="s", final quantity="Time")=0.5 "Time constant of integrator block"; parameter Real Td( final unit="s", final quantity="Time")=0.1 "Time constant of derivative block"; Buildings.Controls.OBC.CDL.Interfaces.RealInput dpBui( final unit="Pa", displayUnit="Pa") "Building static pressure difference, relative to ambient (positive if pressurized)"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1MinOutAirDam "Minimum outdoor air damper status, true when it is open"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "Supply fan status"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yDpBui( final unit="Pa", displayUnit="Pa") "Averaged building static pressure"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRelDam( final unit="1", final min=0, final max=1) "Relief damper commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput dpDisSet( final unit="Pa", displayUnit="Pa", final min=0) "Return fan discharge static pressure setpoint"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yRetFan( final unit="1", final min=0, final max=1) "Return fan commanded speed"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1RetFan "Return fan commanded on"; Buildings.Controls.OBC.CDL.Reals.MovingAverage movMea( final delta=300) "Average building static pressure measurement"; Buildings.Controls.OBC.CDL.Reals.PID conP( final controllerType=conTyp, final k=k, final Ti=Ti, final Td=Td) "Building static pressure controller"; Buildings.Controls.OBC.CDL.Reals.Line linExhAirDam "Exhaust air damper position"; Buildings.Controls.OBC.CDL.Reals.Line linRetFanStaPre "Return fan static pressure setpoint"; Buildings.Controls.OBC.CDL.Reals.Switch swi1 "Relief air damper position"; Buildings.Controls.OBC.CDL.Reals.Switch swi "Return fan discharge static pressure setpoint"; Buildings.Controls.OBC.CDL.Reals.Divide div "Normalized the control error"; Buildings.Controls.OBC.CDL.Reals.Line linRetFanSpe "Return fan speed"; Buildings.Controls.OBC.CDL.Reals.Switch swi2 "Return fan speed setpoint"; protected Buildings.Controls.OBC.CDL.Reals.Sources.Constant dpBuiSetPoi( final k=dpBuiSet) "Building pressure setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant retFanDisPreMin( final k=p_rel_RetFan_min) "Return fan discharge static pressure minimum setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant retFanDisPreMax( final k=p_rel_RetFan_max) "Return fan discharge static pressure maximum setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zer(final k=0) "Zero fan control signal"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zer1(final k=0) "Zero constant"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant con(final k=0.5) "Constant 0.5"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant one(final k=1) "Constant one"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant conOne(final k=1) "Constant one"; Buildings.Controls.OBC.CDL.Logical.And enaDam "Check if the relief damper should be enabled"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant retFanSpeMin( final k=disSpe_min) "Return fan speed when discharge static pressure minimum setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant retFanSpeMax( final k=disSpe_max) "Return fan speed when discharge static pressure maximum setpoint"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zer2( final k=0) "Zero fan control signal"; equation connect(movMea.u, dpBui); connect(swi.u2, u1SupFan); connect(swi.u3, zer.y); connect(zer1.y, linExhAirDam.x1); connect(zer1.y, linExhAirDam.f1); connect(con.y, linExhAirDam.x2); connect(one.y, linExhAirDam.f2); connect(con.y, linRetFanStaPre.x1); connect(one.y, linRetFanStaPre.x2); connect(retFanDisPreMin.y, linRetFanStaPre.f1); connect(retFanDisPreMax.y, linRetFanStaPre.f2); connect(linRetFanStaPre.y, swi.u1); connect(linExhAirDam.y, swi1.u1); connect(swi1.y,yRelDam); connect(zer1.y, swi1.u3); connect(swi.y, dpDisSet); connect(conP.y, linExhAirDam.u); connect(conP.y, linRetFanStaPre.u); connect(dpBuiSetPoi.y, div.u2); connect(movMea.y, div.u1); connect(conOne.y, conP.u_s); connect(div.y, conP.u_m); connect(movMea.y, yDpBui); connect(u1MinOutAirDam, enaDam.u1); connect(u1SupFan, enaDam.u2); connect(enaDam.y, swi1.u2); connect(linRetFanStaPre.y, linRetFanSpe.u); connect(retFanDisPreMin.y, linRetFanSpe.x1); connect(retFanSpeMin.y, linRetFanSpe.f1); connect(retFanDisPreMax.y, linRetFanSpe.x2); connect(retFanSpeMax.y, linRetFanSpe.f2); connect(linRetFanSpe.y, swi2.u1); connect(zer2.y, swi2.u3); connect(u1SupFan, swi2.u2); connect(swi2.y, yRetFan); connect(u1SupFan, y1RetFan); end ReturnFanDirectPressure;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyFan Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyFan

Block to control multi zone VAV AHU supply fan

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyFan

Information

Supply fan control for a multi zone VAV AHU according to Section 5.16.1 of ASHRAE Guideline G36, May 2020.

Supply fan start/stop

Static pressure setpoint reset

Static pressure setpoint shall be reset using trim-respond logic using following parameters as a starting point:

Variable Value Definition
DeviceAHU Supply Fan Associated device
SP0iniSetInitial setpoint
SPminminSetMinimum setpoint
SPmaxmaxSetMaximum setpoint
TddelTimDelay timer
TsamplePeriodTime step
InumIgnReqNumber of ignored requests
RuZonPreResReqNumber of requests
SPtrimtriAmoTrim amount
SPresresAmoRespond amount
SPres_maxmaxResMaximum response per time interval

Static pressure control

Supply fan speed is controlled with a PI controller to maintain duct static pressure at setpoint when the fan is proven on. The setpoint for the PI controller and the measured duct static pressure are normalized with the maximum design static presssure maxSet. Where the zone groups served by the system are small, provide multiple sets of gains that are used in the control loop as a function of a load indicator (such as supply fan airflow rate, the area of the zone groups that are occupied, etc.).

Parameters

TypeNameDefaultDescription
System configuration
Booleanhave_perZonRehBoxfalseCheck if there is any VAV-reheat boxes on perimeter zones
Trim and respond for pressure setpoint
RealiniSet120Initial setpoint [Pa]
RealminSet25Minimum setpoint [Pa]
RealmaxSet Duct design maximum static pressure. It is the Max_DSP shown in Section 3.2.1.1 of Guideline 36 [Pa]
RealdelTim600Delay time after which trim and respond is activated [s]
RealsamplePeriod120Sample period [s]
IntegernumIgnReq2Number of ignored requests
RealtriAmo-12.0Trim amount [Pa]
RealresAmo15Respond amount (must be opposite in to triAmo) [Pa]
RealmaxRes32Maximum response per time interval (same sign as resAmo) [Pa]
Fan PID controller
SimpleControllercontrollerTypeBuildings.Controls.OBC.CDL.T...Type of controller
Realk0.1Gain of controller, normalized using maxSet [1]
RealTi60Time constant of integrator block [s]
RealTd0.1Time constant of derivative block [s]
RealmaxSpe1Maximum allowed fan speed [1]
RealminSpe0.1Lowest allowed fan speed if fan is on [1]
RealiniSpe0.1Initial speed when fan is enabled. It has to be greater than the lowest allowed speed [1]

Connectors

TypeNameDescription
input IntegerInputuOpeModSystem operation mode
input RealInputdpDucMeasured duct static pressure [Pa]
input IntegerInputuZonPreResReqZone static pressure reset requests
output BooleanOutputy1SupFanSupply fan command on
output RealOutputySupFanSupply fan commanded speed [1]

Modelica definition

block SupplyFan "Block to control multi zone VAV AHU supply fan" parameter Boolean have_perZonRehBox = false "Check if there is any VAV-reheat boxes on perimeter zones"; parameter Real iniSet( final unit="Pa", final quantity="PressureDifference") = 120 "Initial setpoint"; parameter Real minSet( final unit="Pa", final quantity="PressureDifference") = 25 "Minimum setpoint"; parameter Real maxSet( final unit="Pa", final quantity="PressureDifference") "Duct design maximum static pressure. It is the Max_DSP shown in Section 3.2.1.1 of Guideline 36"; parameter Real delTim( final unit="s", final quantity="Time")= 600 "Delay time after which trim and respond is activated"; parameter Real samplePeriod( final unit="s", final quantity="Time") = 120 "Sample period"; parameter Integer numIgnReq = 2 "Number of ignored requests"; parameter Real triAmo( final unit="Pa", final quantity="PressureDifference") = -12.0 "Trim amount"; parameter Real resAmo( final unit="Pa", final quantity="PressureDifference") = 15 "Respond amount (must be opposite in to triAmo)"; parameter Real maxRes( final unit="Pa", final quantity="PressureDifference") = 32 "Maximum response per time interval (same sign as resAmo)"; parameter Buildings.Controls.OBC.CDL.Types.SimpleController controllerType=Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller"; parameter Real k(final unit="1")=0.1 "Gain of controller, normalized using maxSet"; parameter Real Ti( final unit="s", final quantity="Time", min=0)=60 "Time constant of integrator block"; parameter Real Td( final unit="s", final quantity="Time", final min=0) = 0.1 "Time constant of derivative block"; parameter Real maxSpe(min=0.1, max=1, unit="1") = 1 "Maximum allowed fan speed"; parameter Real minSpe(min=0.1, max=1, unit="1") = 0.1 "Lowest allowed fan speed if fan is on"; parameter Real iniSpe(min=minSpe, max=1, unit="1") = 0.1 "Initial speed when fan is enabled. It has to be greater than the lowest allowed speed"; Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uOpeMod "System operation mode"; Buildings.Controls.OBC.CDL.Interfaces.RealInput dpDuc( final unit="Pa", final quantity="PressureDifference") "Measured duct static pressure"; Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uZonPreResReq "Zone static pressure reset requests"; Buildings.Controls.OBC.CDL.Interfaces.BooleanOutput y1SupFan "Supply fan command on"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput ySupFan( min=0, max=1, final unit="1") "Supply fan commanded speed"; Buildings.Controls.OBC.ASHRAE.G36.Generic.TrimAndRespond staPreSetRes( final iniSet=iniSet, final minSet=minSet, final maxSet=maxSet, final delTim=delTim, final samplePeriod=samplePeriod, final numIgnReq=numIgnReq, final triAmo=triAmo, final resAmo=resAmo, final maxRes=maxRes) "Static pressure setpoint reset using trim and respond logic"; Buildings.Controls.OBC.CDL.Reals.PIDWithReset conSpe( final controllerType=controllerType, final k=k, final Ti=Ti, final Td=Td, final yMax=maxSpe, final yMin=minSpe, final y_reset=iniSpe) "Supply fan speed control"; protected Buildings.Controls.OBC.CDL.Reals.Sources.Constant zerSpe(k=0) "Zero fan speed when it becomes OFF"; Buildings.Controls.OBC.CDL.Reals.Switch swi "If fan is OFF, fan speed outputs to zero"; Buildings.Controls.OBC.CDL.Logical.Or or1 "Check whether supply fan should be ON"; Buildings.Controls.OBC.CDL.Logical.Or or2 if have_perZonRehBox "Setback or warmup mode"; Buildings.Controls.OBC.CDL.Logical.Or3 or3 "Cool-down or setup or occupied mode"; Buildings.Controls.OBC.CDL.Logical.Sources.Constant con( k=false) if not have_perZonRehBox "Constant true"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt( k=Buildings.Controls.OBC.ASHRAE.G36.Types.OperationModes.coolDown) "Cool down mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt4( k=Buildings.Controls.OBC.ASHRAE.G36.Types.OperationModes.warmUp) "Warm-up mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt1( k=Buildings.Controls.OBC.ASHRAE.G36.Types.OperationModes.setUp) "Set up mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt2( k=Buildings.Controls.OBC.ASHRAE.G36.Types.OperationModes.occupied) "Occupied mode"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant conInt3( k=Buildings.Controls.OBC.ASHRAE.G36.Types.OperationModes.setBack) "Set back mode"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu "Check if current operation mode is cool-down mode"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu1 "Check if current operation mode is setup mode"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu2 "Check if current operation mode is occupied mode"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu3 "Check if current operation mode is setback mode"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu4 "Check if current operation mode is warmup mode"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant gaiNor( final k=maxSet) "Gain for normalization of controller input"; Buildings.Controls.OBC.CDL.Reals.Divide norPSet "Normalization for pressure set point"; Buildings.Controls.OBC.CDL.Reals.Divide norPMea "Normalization of pressure measurement"; Buildings.Controls.OBC.CDL.Discrete.FirstOrderHold firOrdHol( final samplePeriod=samplePeriod) "Extrapolation through the values of the last two sampled input signals"; equation connect(or2.y, or1.u2); connect(or1.y, y1SupFan); connect(or1.y, staPreSetRes.uDevSta); connect(or1.y, swi.u2); connect(conSpe.y, swi.u1); connect(zerSpe.y, swi.u3); connect(swi.y, ySupFan); connect(uZonPreResReq, staPreSetRes.numOfReq); connect(con.y, or1.u2); connect(intEqu.y, or3.u1); connect(intEqu2.y, or3.u3); connect(intEqu1.y, or3.u2); connect(conInt.y, intEqu.u2); connect(conInt1.y, intEqu1.u2); connect(conInt2.y, intEqu2.u2); connect(conInt3.y, intEqu3.u2); connect(conInt4.y, intEqu4.u2); connect(uOpeMod, intEqu.u1); connect(uOpeMod, intEqu1.u1); connect(uOpeMod, intEqu2.u1); connect(uOpeMod, intEqu3.u1); connect(uOpeMod, intEqu4.u1); connect(or3.y, or1.u1); connect(intEqu3.y, or2.u1); connect(intEqu4.y, or2.u2); connect(norPSet.y, conSpe.u_s); connect(norPMea.y, conSpe.u_m); connect(staPreSetRes.y, firOrdHol.u); connect(conSpe.trigger, or1.y); connect(gaiNor.y, norPSet.u2); connect(dpDuc, norPMea.u1); connect(gaiNor.y, norPMea.u2); connect(firOrdHol.y, norPSet.u1); end SupplyFan;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplySignals Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplySignals

Multizone VAV AHU supply air temperature control loop and coil valves position

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplySignals

Information

Block that outputs the supply temperature control loop signal, and the coil valve postions for VAV system with multiple zones, implemented according to Section 5.16.2.3 of the ASHRAE Guideline G36, May 2020.

The supply air temperature control loop signal uTSup is computed using a PI controller that tracks the supply air temperature setpoint TSupSet. If the fan is off, then uTSup = 0.

Heating valve control signal (or modulating electric heating coil if applicable) yHeaCoi and cooling valve control signal yCooCoi are sequenced based on the supply air temperature control loop signal uTSup. From uTSup = uHea_max to uTSup = -1, yHeaCoi increases linearly from 0 to 1. Similarly, uTSup = uCoo_min to uTSup = +1, yCooCoi increases linearly from 0 to 1.

Image of supply temperature loop

The output uTSup can be used in a controller for the economizer.

Parameters

TypeNameDefaultDescription
Booleanhave_heaCoitrueTrue: the AHU has heating coil. It could be the hot water coil, or the electric heating coil
SimpleControllercontrollerTypeBuildings.Controls.OBC.CDL.T...Type of controller for supply air temperature signal
RealkTSup0.05Gain of controller for supply air temperature signal [1/K]
RealTiTSup600Time constant of integrator block for supply temperature control signal [s]
RealTdTSup0.1Time constant of derivative block for supply temperature control signal [s]
RealuHea_max-0.25Upper limit of controller signal when heating coil is off. Require -1 < uHea_max < uCoo_min < 1. [1]
RealuCoo_min0.25Lower limit of controller signal when cooling coil is off. Require -1 < uHea_max < uCoo_min < 1. [1]

Connectors

TypeNameDescription
input RealInputTAirSupMeasured supply air temperature [K]
input RealInputTAirSupSetSupply air temperature setpoint [K]
input BooleanInputu1SupFanSupply fan status
output RealOutputyHeaCoiHeating coil commanded position [1]
output RealOutputyCooCoiCooling coil commanded position [1]
output RealOutputuTSupSupply temperature control signal [1]

Modelica definition

block SupplySignals "Multizone VAV AHU supply air temperature control loop and coil valves position" parameter Boolean have_heaCoi=true "True: the AHU has heating coil. It could be the hot water coil, or the electric heating coil"; parameter Buildings.Controls.OBC.CDL.Types.SimpleController controllerType= Buildings.Controls.OBC.CDL.Types.SimpleController.PI "Type of controller for supply air temperature signal"; parameter Real kTSup(final unit="1/K")=0.05 "Gain of controller for supply air temperature signal"; parameter Real TiTSup( final unit="s", final quantity="Time")=600 "Time constant of integrator block for supply temperature control signal"; parameter Real TdTSup( final unit="s", final quantity="Time")=0.1 "Time constant of derivative block for supply temperature control signal"; parameter Real uHea_max( final min=-0.9, final unit="1")=-0.25 "Upper limit of controller signal when heating coil is off. Require -1 < uHea_max < uCoo_min < 1."; parameter Real uCoo_min( final max=0.9, final unit="1")=0.25 "Lower limit of controller signal when cooling coil is off. Require -1 < uHea_max < uCoo_min < 1."; Buildings.Controls.OBC.CDL.Interfaces.RealInput TAirSup( final unit="K", final displayUnit="degC", final quantity="ThermodynamicTemperature") "Measured supply air temperature"; Buildings.Controls.OBC.CDL.Interfaces.RealInput TAirSupSet( final unit="K", final displayUnit="degC", final quantity="ThermodynamicTemperature") "Supply air temperature setpoint"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "Supply fan status"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yHeaCoi( final min=0, final max=1, final unit="1") if have_heaCoi "Heating coil commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput yCooCoi( final min=0, final max=1, final unit="1") "Cooling coil commanded position"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput uTSup( final max=1, final unit="1", final min=-1) "Supply temperature control signal"; Buildings.Controls.OBC.CDL.Reals.PIDWithReset conTSup( final controllerType=controllerType, final k=kTSup, final Ti=TiTSup, final Td=TdTSup, final yMax=1, final yMin=-1, final reverseActing=false, final y_reset=0) "Controller for supply air temperature control signal (to be used by heating coil, cooling coil and economizer)"; protected Buildings.Controls.OBC.CDL.Reals.Switch swi "Switch to select supply temperature control signal based on status of supply fan"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant uHeaMaxCon( final k=uHea_max) if have_heaCoi "Constant signal to map control action"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant negOne(final k=-1) if have_heaCoi "Negative unity signal"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant uCooMinCon( final k=uCoo_min) "Constant signal to map control action"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant zer(final k=0) "Zero control signal"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant one(final k=1) "Unity signal"; Buildings.Controls.OBC.CDL.Reals.Line conSigCoo( final limitBelow=true, final limitAbove=false) "Cooling control signal"; Buildings.Controls.OBC.CDL.Reals.Line conSigHea( final limitBelow=false, final limitAbove=true) if have_heaCoi "Heating control signal"; equation connect(zer.y,swi. u3); connect(TAirSup, conTSup.u_m); connect(negOne.y,conSigHea. x1); connect(one.y,conSigHea. f1); connect(swi.y,conSigHea. u); connect(swi.y,conSigCoo. u); connect(uHeaMaxCon.y,conSigHea. x2); connect(zer.y,conSigHea. f2); connect(uCooMinCon.y,conSigCoo. x1); connect(zer.y,conSigCoo. f1); connect(one.y,conSigCoo. x2); connect(one.y,conSigCoo. f2); connect(conSigHea.y, yHeaCoi); connect(conSigCoo.y, yCooCoi); connect(swi.y,uTSup); connect(TAirSupSet, conTSup.u_s); connect(u1SupFan, swi.u2); connect(conTSup.y, swi.u1); connect(u1SupFan, conTSup.trigger); end SupplySignals;

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyTemperature Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyTemperature

Supply air temperature setpoint for multi zone system

Buildings.Controls.OBC.ASHRAE.G36.AHUs.MultiZone.VAV.SetPoints.SupplyTemperature

Information

Block that outputs the supply air temperature setpoint and the coil valve control inputs for VAV system with multiple zones, implemented according to Section 5.16.2 of the ASHRAE Guideline G36, May 2020.

The control loop is enabled when the supply air fan u1SupFan is proven on, and disabled and the output set to deadband (no heating, minimum economizer) otherwise.

The supply air temperature setpoint is computed as follows.

Setpoints for TSupCoo_min, TSupCoo_max, TOut_min, TOut_max

Per Section 3.1.4.1, the setpoints are design information.

During occupied and Setup modes (uOpeMod=1, uOpeMod=2)

The TSupSet shall be reset from TSupCoo_min when the outdoor air temperature is TOut_max and above, proportionally up to maximum supply temperature when the outdoor air temperature is TOut_min and below. The maximum supply temperature shall be reset using trim and respond logic between TSupCoo_min and TSupCoo_max. Parameters suggested for the trim and respond logic are shown in the table below. They require adjustment during the commissioning and tuning phase.

Variable Value Definition
DeviceAHU Supply Fan Associated device
SP0iniSetInitial setpoint
SPminTSupCoo_minMinimum setpoint
SPmaxTSupCoo_maxMaximum setpoint
TddelTimDelay timer
TsamplePeriodTime step
InumIgnReqNumber of ignored requests
RuZonTemResReqNumber of requests
SPtrimtriAmoTrim amount
SPresresAmoRespond amount
SPres_maxmaxResMaximum response per time interval

Image of set point reset

During Cool-down modes (uOpeMod=3)

Supply air temperature setpoint TSupSet shall be TSupCoo_min.

During Setback and Warmup modes (uOpeMod=4, uOpeMod=5)

Supply air temperature setpoint TSupSet shall be TSupWarUpSetBac.

Parameters

TypeNameDefaultDescription
Temperatures
RealTSupCoo_min285.15Lowest cooling supply air temperature setpoint when the outdoor air temperature is at the higher value of the reset range and above [K]
RealTSupCoo_max291.15Highest cooling supply air temperature setpoint. It is typically 18 degC (65 degF) in mild and dry climates, 16 degC (60 degF) or lower in humid climates [K]
RealTOut_min289.15Lower value of the outdoor air temperature reset range. Typically value is 16 degC (60 degF) [K]
RealTOut_max294.15Higher value of the outdoor air temperature reset range. Typically value is 21 degC (70 degF) [K]
RealTSupWarUpSetBac308.15Supply temperature in warm up and set back mode [K]
Trim and respond logic
RealdelTim600Delay timer [s]
RealsamplePeriod120Sample period of component [s]
IntegernumIgnReq2Number of ignorable requests for TrimResponse logic
RealtriAmo0.1Trim amount [K]
RealresAmo-0.2Response amount [K]
RealmaxRes-0.6Maximum response per time interval [K]

Connectors

TypeNameDescription
input RealInputTOutOutdoor air temperature [K]
input BooleanInputu1SupFanSupply fan status
input IntegerInputuOpeModSystem operation mode
input IntegerInputuZonTemResReqZone cooling supply air temperature reset request
output RealOutputTAirSupSetSupply air temperature setpoint [K]

Modelica definition

block SupplyTemperature "Supply air temperature setpoint for multi zone system" parameter Real TSupCoo_min( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=285.15 "Lowest cooling supply air temperature setpoint when the outdoor air temperature is at the higher value of the reset range and above"; parameter Real TSupCoo_max( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=291.15 "Highest cooling supply air temperature setpoint. It is typically 18 degC (65 degF) in mild and dry climates, 16 degC (60 degF) or lower in humid climates"; parameter Real TOut_min( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=289.15 "Lower value of the outdoor air temperature reset range. Typically value is 16 degC (60 degF)"; parameter Real TOut_max( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=294.15 "Higher value of the outdoor air temperature reset range. Typically value is 21 degC (70 degF)"; parameter Real TSupWarUpSetBac( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=308.15 "Supply temperature in warm up and set back mode"; parameter Real delTim( final unit="s", final quantity="Time") = 600 "Delay timer"; parameter Real samplePeriod( final unit="s", final quantity="Time", final min=1E-3) = 120 "Sample period of component"; parameter Integer numIgnReq = 2 "Number of ignorable requests for TrimResponse logic"; parameter Real triAmo( final unit="K", displayUnit="K", final quantity="TemperatureDifference") = 0.1 "Trim amount"; parameter Real resAmo( final unit="K", displayUnit="K", final quantity="TemperatureDifference") = -0.2 "Response amount"; parameter Real maxRes( final unit="K", displayUnit="K", final quantity="TemperatureDifference") = -0.6 "Maximum response per time interval"; Buildings.Controls.OBC.CDL.Interfaces.RealInput TOut( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature") "Outdoor air temperature"; Buildings.Controls.OBC.CDL.Interfaces.BooleanInput u1SupFan "Supply fan status"; Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uOpeMod "System operation mode"; Buildings.Controls.OBC.CDL.Interfaces.IntegerInput uZonTemResReq "Zone cooling supply air temperature reset request"; Buildings.Controls.OBC.CDL.Interfaces.RealOutput TAirSupSet( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature") "Supply air temperature setpoint"; Buildings.Controls.OBC.ASHRAE.G36.Generic.TrimAndRespond maxSupTemRes( final delTim=delTim, final iniSet=iniSet, final minSet=minSet, final maxSet=maxSet, final samplePeriod=samplePeriod, final numIgnReq=numIgnReq, final triAmo=triAmo, final resAmo=resAmo, final maxRes=maxRes) "Maximum cooling supply temperature reset"; protected parameter Real TDeaBan( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=273.15+26 "Default supply temperature setpoint when the AHU is disabled"; parameter Real iniSet( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=TSupCoo_max "Initial setpoint"; parameter Real maxSet( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=TSupCoo_max "Maximum setpoint"; parameter Real minSet( final unit="K", displayUnit="degC", final quantity="ThermodynamicTemperature")=TSupCoo_min "Minimum setpoint"; Buildings.Controls.OBC.CDL.Reals.Line lin "Supply temperature distributes linearly between minimum and maximum supply air temperature, according to outdoor temperature"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant minOutTem( final k=TOut_min) "Lower value of the outdoor air temperature reset range"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant maxOutTem( final k=TOut_max) "Higher value of the outdoor air temperature reset range"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant minSupTem( final k=TSupCoo_min) "Lowest cooling supply air temperature setpoint"; Buildings.Controls.OBC.CDL.Logical.And and1 "Check if it is in Warmup or Setback mode"; Buildings.Controls.OBC.CDL.Reals.Sources.Constant supTemWarUpSetBac( final k=TSupWarUpSetBac) "Supply temperature setpoint under warm-up and setback mode"; Buildings.Controls.OBC.CDL.Reals.Switch swi1 "If operation mode is warm-up or setback modes, setpoint shall be 35 degC"; Buildings.Controls.OBC.CDL.Reals.Switch swi2 "If operation mode is setup or cool-down, setpoint shall be the lowest cooling supply setpoint"; Buildings.Controls.OBC.CDL.Reals.Switch swi3 "Check output regarding supply fan status"; Buildings.Controls.OBC.CDL.Integers.Sources.Constant cooDowMod( final k=3) "Cooldown mode index"; Buildings.Controls.OBC.CDL.Integers.LessThreshold intLesThr1( final t=6) "Check if operation mode index is less than 6 (freeze protection mode)"; Buildings.Controls.OBC.CDL.Integers.GreaterThreshold intGreThr1( final t=3) "Check if operation mode index is greater than 3 (setup mode)"; Buildings.Controls.OBC.CDL.Integers.LessThreshold intLesThr2( final t=3) "Check if operation mode index is less than 3 (setup mode)"; Buildings.Controls.OBC.CDL.Integers.GreaterThreshold intGreThr2( final t=0) "Check if operation mode index is greater than 0 (unoccupied mode)"; Buildings.Controls.OBC.CDL.Logical.And and2 "Check if it is in occupied or setup mode"; Buildings.Controls.OBC.CDL.Reals.Switch swi4 "If operation mode is occupied or setup ,mode, setpoint shall be reset"; Buildings.Controls.OBC.CDL.Integers.Equal intEqu "Check if it is in cooldown mode"; CDL.Reals.Sources.Constant TDea(final k=TDeaBan) "Deadband supply temperature setpoint"; equation connect(minOutTem.y, lin.x1); connect(TOut, lin.u); connect(maxOutTem.y, lin.x2); connect(minSupTem.y, lin.f2); connect(and1.y, swi1.u2); connect(supTemWarUpSetBac.y, swi1.u1); connect(minSupTem.y, swi2.u1); connect(swi2.y, swi1.u3); connect(u1SupFan, swi3.u2); connect(swi1.y, swi3.u1); connect(intLesThr1.y, and1.u1); connect(intGreThr1.y, and1.u2); connect(uOpeMod, intLesThr1.u); connect(uOpeMod, intGreThr1.u); connect(uZonTemResReq, maxSupTemRes.numOfReq); connect(u1SupFan, maxSupTemRes.uDevSta); connect(maxSupTemRes.y, lin.f1); connect(swi3.y, TAirSupSet); connect(cooDowMod.y, intEqu.u2); connect(uOpeMod, intEqu.u1); connect(intEqu.y, swi2.u2); connect(uOpeMod, intLesThr2.u); connect(uOpeMod, intGreThr2.u); connect(intLesThr2.y, and2.u1); connect(intGreThr2.y, and2.u2); connect(and2.y, swi4.u2); connect(lin.y, swi4.u1); connect(swi4.y, swi2.u3); connect(TDea.y, swi4.u3); connect(TDea.y, swi3.u3); end SupplyTemperature;