EnergyPlus Autosize

UNDER DEVELOPMENT This page summarizes how the EnergyPlus outputs from the eio file can be used to hard size the autosize fields in the EnergyPlus idf file.

System 6

For the system 6, user can find all of the autosize fields in the eio file for the 'AirTerminal:SingleDuct:ParallelPIU:Reheat,except theMaximum Hot Water or Steam Flow Rate {m3/s}. Since the system is electric, Coil:Heating:ElectricandCoil Heating Electric 13, Maximum Hot Water or Steam Flow Rate {m3/s}does need to be hard sized from the eio file. Part of the idf for theAirTerminal:SingleDuct:ParallelPIU:Reheat,` object and the corresponding eio section are presented below:

IDF File Section

AirTerminal:SingleDuct:ParallelPIU:Reheat,
  Air Terminal Single Duct Parallel PIU Reheat 12, !- Name
  Always On Discrete,                     !- Availability Schedule Name
  Autosize,                               !- Maximum Primary Air Flow Rate {m3/s}
  Autosize,                               !- Maximum Secondary Air Flow Rate {m3/s}
  Autosize,                               !- Minimum Primary Air Flow Fraction
  Autosize,                               !- Fan On Flow Fraction
  Node 71,                                !- Supply Air Inlet Node Name
  Node 72,                                !- Secondary Air Inlet Node Name
  Node 69,                                !- Outlet Node Name
  Air Terminal Single Duct Parallel PIU Reheat 12 Mixer Outlet, !- Reheat Coil Air Inlet Node Name
  Air Terminal Single Duct Parallel PIU Reheat 12 Mixer, !- Zone Mixer Name
  Fan Constant Volume 12,                 !- Fan Name
  Coil:Heating:Electric,                  !- Reheat Coil Object Type
  Coil Heating Electric 13,               !- Reheat Coil Name
  Autosize,                               !- Maximum Hot Water or Steam Flow Rate {m3/s}
  0,                                      !- Minimum Hot Water or Steam Flow Rate {m3/s}
  ,                                       !- Hot Water or Steam Inlet Node Name
  0.001;

EIO File Section

! <Component Sizing Information>, Component Type, Component Name, Input Field Description, Value
Component Sizing Information, AirTerminal:SingleDuct:ParallelPIU:Reheat, AIR TERMINAL SINGLE DUCT PARALLEL PIU REHEAT 12, Design Size Maximum Primary Air Flow Rate [m3/s], 0.96846
Component Sizing Information, AirTerminal:SingleDuct:ParallelPIU:Reheat, AIR TERMINAL SINGLE DUCT PARALLEL PIU REHEAT 12, Design Size Maximum Secondary Air Flow Rate [m3/s], 0.96846
Component Sizing Information, AirTerminal:SingleDuct:ParallelPIU:Reheat, AIR TERMINAL SINGLE DUCT PARALLEL PIU REHEAT 12, Design Size Minimum Primary Air Flow Fraction, 7.39604E-002
Component Sizing Information, AirTerminal:SingleDuct:ParallelPIU:Reheat, AIR TERMINAL SINGLE DUCT PARALLEL PIU REHEAT 12, Design Size Fan On Flow Fraction, 7.39604E-002
Component Sizing Information, Fan:ConstantVolume, FAN CONSTANT VOLUME 12, Design Size Maximum Flow Rate [m3/s], 0.96846

User can see that there is no field for the Maximum Hot Water or Steam Flow Rate {m3/s} in the eio file.

This is similarly valid for system 8, for the 'ZoneHVAC:UnitHeater' object in the RefBldgLargeHotelPre1980_v1.4_7.2_5A_USA_IL_CHICAGO-OHARE.

IDF File Section

ZoneHVAC:UnitHeater,
  Corridor_Flr_6 Unit Heater,  !- Name
  ALWAYS_ON,               !- Availability Schedule Name
  Corridor_Flr_6 Unit Heater Exhaust Node,  !- Air Inlet Node Name
  Corridor_Flr_6 Unit Heater Inlet Node Name,  !- Air Outlet Node Name
  Fan:ConstantVolume,      !- Supply Air Fan Object Type
  Corridor_Flr_6 Unit HeaterFan,  !- Supply Air Fan Name
  AUTOSIZE,                !- Maximum Supply Air Flow Rate {m3/s}
  OnOff,                   !- Fan Control Type
  Coil:Heating:Electric,   !- Heating Coil Object Type
  Corridor_Flr_6 Unit Heater coil,  !- Heating Coil Name
  AUTOSIZE,                !- Maximum Hot Water or Steam Flow Rate {m3/s}
  0.0,                     !- Minimum Hot Water or Steam Flow Rate {m3/s}
  0.001,                   !- Heating Convergence Tolerance
  ;                        !- Availability Manager List Name

EIO File Section

Component Sizing Information, ZoneHVAC:UnitHeater, CORRIDOR_FLR_6 UNIT HEATER, Maximum Supply Air Flow Rate [m3/s], 0.55190