Nodes in the simulation[LINK]
In the EnergyPlus data structure, the nodes are where each
component model gets its input and where it places its output.
The module DataLoopNode contains all the node related
data. In particular, the array Node contains the
state variables and mass flows for all the nodes in the
problem being simulated.
! Valid Fluid Types for Nodes
INTEGER, PARAMETER :: NodeType_Unknown = 0 ! ‘blank’
INTEGER, PARAMETER :: NodeType_Air = 1 ! ‘Air’
INTEGER, PARAMETER :: NodeType_Water = 2 ! ‘Water’
INTEGER, PARAMETER :: NodeType_Steam = 3 ! ‘Steam’
INTEGER, PARAMETER :: NodeType_Electric = 4 !
‘Electric’
TYPE NodeData
INTEGER :: FluidType =
0 ! must be one of the valid parameters
INTEGER :: FluidIndex =
0 ! For Fluid Properties
REAL(r64) :: Temp = 0.d0 !
{C}
REAL(r64) :: TempMin = 0.d0 !
{C}
REAL(r64) :: TempMax = 0.d0 !
{C}
REAL(r64) :: TempSetPoint =
SensedNodeFlagValue ! {C}
REAL(r64) :: TempLastTimestep = 0.d0 !
[C} DSU
REAL(r64) :: MassFlowRateRequest = 0.d0 !
{kg/s} DSU
REAL(r64) :: MassFlowRate = 0.d0 !
{kg/s}
REAL(r64) :: MassFlowRateMin = 0.d0 !
{kg/s}
REAL(r64) :: MassFlowRateMax =
SensedNodeFlagValue ! {kg/s}
REAL(r64) :: MassFlowRateMinAvail = 0.d0 !
{kg/s}
REAL(r64) :: MassFlowRateMaxAvail = 0.d0 !
{kg/s}
REAL(r64) :: MassFlowRateSetPoint = 0.d0 !
{kg/s}
REAL(r64) :: Quality = 0.d0 !
{0.0-1.0 vapor fraction/percent}
REAL(r64) :: Press = 0.d0 !
{Pa}
REAL(r64) :: Enthalpy = 0.d0 !
{J/kg}
REAL(r64) :: EnthalpyLastTimestep = 0.d0 !
{J/kg} DSU for steam?
REAL(r64) :: HumRat = 0.d0 !
{}
REAL(r64) :: HumRatMin =
SensedNodeFlagValue ! {}
REAL(r64) :: HumRatMax =
SensedNodeFlagValue ! {}
REAL(r64) :: HumRatSetPoint =
SensedNodeFlagValue ! {}
REAL(r64) :: TempSetPointHi =
SensedNodeFlagValue ! {C}
REAL(r64) :: TempSetPointLo =
SensedNodeFlagValue ! {C}
REAL(r64) :: Height = -1.d0 !
{m}
! Following are for Outdoor Air Nodes “read only”
REAL(r64) :: OutAirDryBulb = 0.d0 !
{C}
LOGICAL ::
EMSOverrideOutAirDryBulb = .FALSE. ! if true, the EMS is
calling to override outdoor air node drybulb setting
REAL(r64) :: EMSValueForOutAirDryBulb = 0.d0 !
value EMS is directing to use for outdoor air node’s drybulb
{C}
REAL(r64) :: OutAirWetBulb = 0.d0 !
{C}
LOGICAL ::
EMSOverrideOutAirWetBulb = .FALSE. ! if true, the EMS is
calling to override outdoor air node wetbulb setting
REAL(r64) :: EMSValueForOutAirWetBulb = 0.d0 !
value EMS is directing to use for outdoor air node’s wetbulb
{C}
! Contaminant
REAL(r64) :: CO2 = 0.d0 !
{ppm}
REAL(r64) :: CO2SetPoint = 0.d0 !
{ppm}
END TYPE NodeData
TYPE MoreNodeData
REAL(r64) :: RelHumidity = 0.d0 !
{%}
REAL(r64) :: ReportEnthalpy = 0.d0 !
specific enthalpy calculated at the HVAC timestep [J/kg]
REAL(r64) :: VolFlowRateStdRho = 0.d0 !
volume flow rate at standard density [m3/s]
REAL(r64) :: VolFlowRateCrntRho = 0.d0 !
volume flow rate at current density, only used for air nodes
[m3/s]
REAL(r64) :: WetbulbTemp = 0.d0 !
wetbulb temperature [C]
REAL(r64) :: AirDensity = 0.d0 !
reported air density at standard density [kg/m3]
END TYPE
MoreNodeData
TYPE (NodeData),
ALLOCATABLE, DIMENSION(:) ::
Node !dim to num nodes in SimHVAC
TYPE (NodeData) :: DefaultNodeValues =
&
NodeData(0, & ! FluidType
0, & ! FluidIndex
0.0D0, & ! Temp {C}
0.0D0, & ! TempMin {C}
0.0D0, & ! TempMax {C}
SensedNodeFlagValue, & ! TempSetPoint {C}
0.0D0, & ! TempLastTimeStep
{C}
0.0D0, & ! MassFlowRateRequest
{kg/s}
0.0D0, & ! MassFlowRate {kg/s}
0.0D0, & ! MassFlowRateMin
{kg/s}
0.0D0, & ! MassFlowRateMax
{kg/s}
0.0D0, & ! MassFlowRateMinAvail
{kg/s}
0.0D0, & ! MassFlowRateMaxAvail
{kg/s}
0.0D0, & ! MassFlowRateSetPoint
{kg/s}
0.0D0, & ! Quality {0.0-1.0 vapor
fraction/percent}
0.0D0, & ! Press {Pa}
REAL(r64) ::
0.0D0, & ! Enthalpy {J/kg}
0.0D0, & ! EnthalpyLastTimeStep
{J/kg}
0.0D0, & ! HumRat {}
SensedNodeFlagValue, & ! HumRatMin {}
SensedNodeFlagValue, & ! HumRatMax {}
SensedNodeFlagValue, & ! HumRatSetPoint {}
SensedNodeFlagValue, & ! TempSetPointHi {C}
SensedNodeFlagValue, & ! TempSetPointLo {C}
-1.0D0, & ! Height {m}
0.0D0, & ! OutAirDryBulb {C}
.FALSE., & !
EMSOverrideOutAirDryBulb
0.0D0, & !
EMSValueForOutAirDryBulb {C}
0.0D0, & ! OutAirWetBulb {C}
.FALSE., & !
EMSOverrideOutAirWetBulb
0.0D0, & !
EMSValueForOutAirWetBulb {C}
0.0D0, & ! CO2 {ppm}
0.0D0) ! CO2 setpoint {ppm}
TYPE (MoreNodeData), ALLOCATABLE, DIMENSION(:) ::
MoreNodeInfo
In our example module NewHVACComponent, the
subroutine InitNewHVACComponent is responsible for
obtaining the input data from the inlet node(s) and putting it
into the component data structure for use in
CalcNewHVACComponent. Then
UpdateNewHVACComponent takes the calculated data and
moves it to the outlet nodes for use by other components.
EnergyPlus component models are assumed to be direct models:
inlets are input to the calculation and outlets are output
from the calculations.
Nodes in the simulation[LINK]
In the EnergyPlus data structure, the nodes are where each component model gets its input and where it places its output. The module DataLoopNode contains all the node related data. In particular, the array Node contains the state variables and mass flows for all the nodes in the problem being simulated.
! Valid Fluid Types for Nodes
INTEGER, PARAMETER :: NodeType_Unknown = 0 ! ‘blank’
INTEGER, PARAMETER :: NodeType_Air = 1 ! ‘Air’
INTEGER, PARAMETER :: NodeType_Water = 2 ! ‘Water’
INTEGER, PARAMETER :: NodeType_Steam = 3 ! ‘Steam’
INTEGER, PARAMETER :: NodeType_Electric = 4 ! ‘Electric’
TYPE NodeData
INTEGER :: FluidType = 0 ! must be one of the valid parameters
INTEGER :: FluidIndex = 0 ! For Fluid Properties
REAL(r64) :: Temp = 0.d0 ! {C}
REAL(r64) :: TempMin = 0.d0 ! {C}
REAL(r64) :: TempMax = 0.d0 ! {C}
REAL(r64) :: TempSetPoint = SensedNodeFlagValue ! {C}
REAL(r64) :: TempLastTimestep = 0.d0 ! [C} DSU
REAL(r64) :: MassFlowRateRequest = 0.d0 ! {kg/s} DSU
REAL(r64) :: MassFlowRate = 0.d0 ! {kg/s}
REAL(r64) :: MassFlowRateMin = 0.d0 ! {kg/s}
REAL(r64) :: MassFlowRateMax = SensedNodeFlagValue ! {kg/s}
REAL(r64) :: MassFlowRateMinAvail = 0.d0 ! {kg/s}
REAL(r64) :: MassFlowRateMaxAvail = 0.d0 ! {kg/s}
REAL(r64) :: MassFlowRateSetPoint = 0.d0 ! {kg/s}
REAL(r64) :: Quality = 0.d0 ! {0.0-1.0 vapor fraction/percent}
REAL(r64) :: Press = 0.d0 ! {Pa}
REAL(r64) :: Enthalpy = 0.d0 ! {J/kg}
REAL(r64) :: EnthalpyLastTimestep = 0.d0 ! {J/kg} DSU for steam?
REAL(r64) :: HumRat = 0.d0 ! {}
REAL(r64) :: HumRatMin = SensedNodeFlagValue ! {}
REAL(r64) :: HumRatMax = SensedNodeFlagValue ! {}
REAL(r64) :: HumRatSetPoint = SensedNodeFlagValue ! {}
REAL(r64) :: TempSetPointHi = SensedNodeFlagValue ! {C}
REAL(r64) :: TempSetPointLo = SensedNodeFlagValue ! {C}
REAL(r64) :: Height = -1.d0 ! {m}
! Following are for Outdoor Air Nodes “read only”
REAL(r64) :: OutAirDryBulb = 0.d0 ! {C}
LOGICAL :: EMSOverrideOutAirDryBulb = .FALSE. ! if true, the EMS is calling to override outdoor air node drybulb setting
REAL(r64) :: EMSValueForOutAirDryBulb = 0.d0 ! value EMS is directing to use for outdoor air node’s drybulb {C}
REAL(r64) :: OutAirWetBulb = 0.d0 ! {C}
LOGICAL :: EMSOverrideOutAirWetBulb = .FALSE. ! if true, the EMS is calling to override outdoor air node wetbulb setting
REAL(r64) :: EMSValueForOutAirWetBulb = 0.d0 ! value EMS is directing to use for outdoor air node’s wetbulb {C}
! Contaminant
REAL(r64) :: CO2 = 0.d0 ! {ppm}
REAL(r64) :: CO2SetPoint = 0.d0 ! {ppm}
END TYPE NodeData
TYPE MoreNodeData
REAL(r64) :: RelHumidity = 0.d0 ! {%}
REAL(r64) :: ReportEnthalpy = 0.d0 ! specific enthalpy calculated at the HVAC timestep [J/kg]
REAL(r64) :: VolFlowRateStdRho = 0.d0 ! volume flow rate at standard density [m3/s]
REAL(r64) :: VolFlowRateCrntRho = 0.d0 ! volume flow rate at current density, only used for air nodes [m3/s]
REAL(r64) :: WetbulbTemp = 0.d0 ! wetbulb temperature [C]
REAL(r64) :: AirDensity = 0.d0 ! reported air density at standard density [kg/m3]
END TYPE MoreNodeData
TYPE (NodeData), ALLOCATABLE, DIMENSION(:) :: Node !dim to num nodes in SimHVAC
TYPE (NodeData) :: DefaultNodeValues = &
NodeData(0, & ! FluidType
0, & ! FluidIndex
0.0D0, & ! Temp {C}
0.0D0, & ! TempMin {C}
0.0D0, & ! TempMax {C}
SensedNodeFlagValue, & ! TempSetPoint {C}
0.0D0, & ! TempLastTimeStep {C}
0.0D0, & ! MassFlowRateRequest {kg/s}
0.0D0, & ! MassFlowRate {kg/s}
0.0D0, & ! MassFlowRateMin {kg/s}
0.0D0, & ! MassFlowRateMax {kg/s}
0.0D0, & ! MassFlowRateMinAvail {kg/s}
0.0D0, & ! MassFlowRateMaxAvail {kg/s}
0.0D0, & ! MassFlowRateSetPoint {kg/s}
0.0D0, & ! Quality {0.0-1.0 vapor fraction/percent}
0.0D0, & ! Press {Pa} REAL(r64) ::
0.0D0, & ! Enthalpy {J/kg}
0.0D0, & ! EnthalpyLastTimeStep {J/kg}
0.0D0, & ! HumRat {}
SensedNodeFlagValue, & ! HumRatMin {}
SensedNodeFlagValue, & ! HumRatMax {}
SensedNodeFlagValue, & ! HumRatSetPoint {}
SensedNodeFlagValue, & ! TempSetPointHi {C}
SensedNodeFlagValue, & ! TempSetPointLo {C}
-1.0D0, & ! Height {m}
0.0D0, & ! OutAirDryBulb {C}
.FALSE., & ! EMSOverrideOutAirDryBulb
0.0D0, & ! EMSValueForOutAirDryBulb {C}
0.0D0, & ! OutAirWetBulb {C}
.FALSE., & ! EMSOverrideOutAirWetBulb
0.0D0, & ! EMSValueForOutAirWetBulb {C}
0.0D0, & ! CO2 {ppm}
0.0D0) ! CO2 setpoint {ppm}
TYPE (MoreNodeData), ALLOCATABLE, DIMENSION(:) :: MoreNodeInfo
In our example module NewHVACComponent, the subroutine InitNewHVACComponent is responsible for obtaining the input data from the inlet node(s) and putting it into the component data structure for use in CalcNewHVACComponent. Then UpdateNewHVACComponent takes the calculated data and moves it to the outlet nodes for use by other components. EnergyPlus component models are assumed to be direct models: inlets are input to the calculation and outlets are output from the calculations.
Documentation content copyright © 1996-2026 The Board of Trustees of the University of Illinois and the Regents of the University of California through the Ernest Orlando Lawrence Berkeley National Laboratory. All rights reserved. EnergyPlus is a trademark of the US Department of Energy.
This documentation is made available under the EnergyPlus Open Source License v1.0.