## Input for Design Calculations and Component Autosizing[LINK]

In order for EnergyPlus to successfully calculate zone design heating and cooling loads and air flow rates and for the program to use these results to automatically size the HVAC components a number of input objects must be present and certain object input fields must be entered.

• The input file should contain a SimulationControl object. The 1st field Do Zone Sizing Calculation should be entered as Yes. This will cause a zone sizing simulation to be done using all the sizing periods in the input file as weather. If there are no air or water loops in the HVAC input fields 2 and 3 can be set to No. If there are one or more air loops (i.e., there is at least one AirLoopHVAC object in the input file) then the 2nd field Do System Sizing Calculation should be entered as Yes. If there are one or more water loops (Plant Loop objects) then the 3rd field Do Plant Sizing Calculation should be set to Yes. Finally either the 4th field (Run Simulation for Sizing Periods) or the 5th field (Run Simulation for Weather File Run Periods) should be set to Yes in order to autosize the components and do a real simulation using the autosized components. The component autosizing calculations are done on the first pass through the HVAC system in the real simulation.
• There must be at least 2 (up to any number) SizingPeriod objects present. Normally one will be for summer conditions and one for winter. The summer day should normally have the field Day Type set to SummerDesignDay. The winter design day should normally have Day Type set to WinterDesignDay.
• To apply a global sizing factor include the Sizing:Parameters object.
• For each controlled zone in the input file there should be a corresponding Sizing:Zone object. Similarly for each AirLoopHVAC there should be a Sizing:System object. And for each Plant or Condenser Loop there should be a Sizing:Plant object. Note however that if a controlled zone has no corresponding Zone Sizing object the data from the first Zone Sizing object will be used. Thus if all the zone sizing information is the same only one Zone Sizing object need be entered.
• Only controlled zones are included in the zone and system sizing calculations. Thus for a design air flow rate to be calculated for a zone, it must contain a thermostat even though it might not need or have a thermostat in the full simulation. An illustration would be a three zone building with a packaged single zone system and a thermostat in one of the zones. In order for the two slave zones to be included in the design air flow calculations they must be treated as if they have a thermostat: there must be a ZoneControl:Thermostat for each of the slave zones.
• Some attention should be paid to schedules. In a weekly schedule object the 9th and 10th day schedules are for summer and winter design days respectively. This means that if a SizingPeriod object has field Day Type set to SummerDesignDay the day schedule for summer sizing periods will be in effect. Similarly if a SizingPeriod object has field Day Type set to WinterDesignDay the day schedule for winter sizing periods will be in effect. Some possible applications of this capability are:

1. setting internal loads (lights, equipment, occupancy) to maximum all day for cooling and to zero all day for heating;
2. setting heating and cooling thermostat set points to constant values (no set up or set back);
3. setting heating and cooling equipment to be always on.

None of these applications are necessarily recommended but these and other uses of the special summer/winter design day schedules may prove useful for specific situations.

• Other than zone thermostat setpoints, the sizing calculations generally know nothing about the system control inputs such as setpoints and availability schedules. The user must coordinate sizing inputs with the actual simulation control inputs.
• The sizing calculations only recognize the presence of central heating and cooling coils, preheat and precool coils and reheat coils. These are assumed to deliver the various supply temperatures specified in the Sizing:System and Sizing:Zone objects. The impact of ther components such as heat recovery, dehumidifiers, fans, and pumps are not accounted for in the sizing calculations.

For autosizing to occur at the component level the user must enter the special value autosize in the numeric fields for which autosizing is available. Those fields can be found by looking at the Energy+.idd data dictionary file or under individual object details in this document. Fields that can be autosized are denoted with the comment \autosizable. The components and fields that are autosizable are listed in the following table. Note that spaces may be inserted in object names to facilitate readability.

Details of Autosizable Objects/Fields
Component / Object Name Autosizable Fields
AirConditioner: VariableRefrigerantFlow
Gross Rated Total Cooling Capacity
Gross Rated Heating Capacity
Resistive Defrost Heater Capacity
Water Condenser Volume Flow Rate
Evaporative Condenser Air Flow Rate
Evaporative Condenser Pump Rated Power Consumption
AirLoopHVAC
Design Supply Air Flow Rate
AirLoopHVAC:Unitary:Furnace: HeatCool
Maximum Supply Air Temperature
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Needed
AirLoopHVAC:Unitary:Furnace: HeatOnly
Maximum Supply Air Temperature
Supply Air Flow Rate
AirLoopHVAC:UnitaryHeatCool
Maximum Supply Air Temperature
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Needed
AirLoopHVAC:UnitaryHeatCool: VAVChangeoverBypass
System Air Flow Rate During Cooling Operation
System Air Flow Rate During Heating Operation
System Air Flow Rate When No Cooling or Heating is Needed
Outdoor Air Flow Rate During Cooling Operation
Outdoor Air Flow Rate During Heating Operation
Outdoor Air Flow Rate When No Cooling or Heating is Needed
AirLoopHVAC:UnitaryHeatOnly
Maximum Supply Air Temperature
Supply Air Flow Rate
AirLoopHVAC:UnitaryHeatPump: AirToAir
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Needed
Maximum Supply Air Temperature from Supplemental Heater
AirLoopHVAC:UnitaryHeatPump: AirToAir:MultiSpeed
Maximum Supply Air Temperature from Supplemental Heater
Supply Air Flow Rate When No Cooling or Heating is Needed
Speed 1 Supply Air Flow Rate During Heating Operation
Speed 2 Supply Air Flow Rate During Heating Operation
Speed 3 Supply Air Flow Rate During Heating Operation
Speed 4 Supply Air Flow Rate During Heating Operation
Speed 1 Supply Air Flow Rate During Cooling Operation
Speed 2 Supply Air Flow Rate During Cooling Operation
Speed 3 Supply Air Flow Rate During Cooling Operation
Speed 4 Supply Air Flow Rate During Cooling Operation
AirLoopHVAC:UnitaryHeatPump: WaterToAir
Supply Air Flow Rate
Maximum Supply Air Temperature from Supplemental Heater
AirLoopHVAC:UnitarySystem
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Required
Maximum Supply Air Temperature
AirTerminal:DualDuct: ConstantVolume
Maximum Air Flow Rate
AirTerminal:DualDuct:VAV
Maximum Damper Air Flow Rate
AirTerminal:DualDuct:VAV: OutdoorAir
Maximum Terminal Air Flow Rate
AirTerminal:SingleDuct: ConstantVolume:CooledBeam
Supply Air Volumetric Flow Rate
Maximum Total Chilled Water Volumetric Flow Rate
Number of Beams
Beam Length
AirTerminal:SingleDuct: ConstantVolume:FourPipeInduction
Maximum Total Air Flow Rate
Maximum Hot Water Flow Rate
Maximum Cold Water Flow Rate
AirTerminal:SingleDuct: ConstantVolume:Reheat
Maximum Air Flow Rate
Maximum Hot Water or Steam Flow Rate
AirTerminal:SingleDuct:ParallelPIU: Reheat
Maximum Primary Air Flow Rate
Maximum Secondary Air Flow Rate
Minimum Primary Air Flow Fraction
Fan On Flow Fraction
Maximum Hot Water or Steam Flow Rate
AirTerminal:SingleDuct:SeriesPIU: Reheat
Maximum Air Flow Rate
Maximum Primary Air Flow Rate
Minimum Primary Air Flow Fraction
Maximum Hot Water or Steam Flow Rate
AirTerminal:SingleDuct: Uncontrolled
Maximum Air Flow Rate
AirTerminal:SingleDuct:VAV: HeatAndCool:NoReheat
Maximum Air Flow Rate
AirTerminal:SingleDuct:VAV: HeatAndCool:Reheat
Maximum Air Flow Rate
Maximum Hot Water or Steam Flow Rate
AirTerminal:SingleDuct:VAV: NoReheat
Maximum Air Flow Rate
AirTerminal:SingleDuct:VAV:Reheat
Maximum Air Flow Rate
Maximum Hot Water or Steam Flow Rate
AirTerminal:SingleDuct:VAV:Reheat: VariableSpeedFan
Maximum Cooling Air Flow Rate
Maximum Heating Air Flow Rate
Maximum Hot Water or Steam Flow Rate
Boiler:HotWater
Nominal Capacity
Design Water Flow Rate
Boiler:Steam
Nominal Capacity
Branch
Maximum Flow Rate
Chiller:Absorption
Nominal Capacity
Nominal Pumping Power
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Design Generator Fluid Flow Rate
Chiller:Absorption:Indirect
Nominal Capacity
Nominal Pumping Power
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Design Generator Fluid Flow Rate
Chiller:CombustionTurbine
Nominal Capacity
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Gas Turbine Engine Capacity
Chiller:ConstantCOP
Nominal Capacity
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Chiller:Electric
Nominal Capacity
Design Chilled Water Flow Rate
Design Condenser Fluid Flow Rate
Design Heat Recovery Water Flow Rate
Chiller:Electric:EIR
Reference Capacity
Reference Chilled Water Flow Rate
Reference Condenser Fluid Flow Rate
Design Heat Recovery Water Flow Rate
Chiller:Electric:ReformulatedEIR
Reference Capacity
Reference Chilled Water Flow Rate
Reference Condenser Water Flow Rate
Design Heat Recovery Water Flow Rate
Chiller:EngineDriven
Nominal Capacity
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
ChillerHeater:Absorption: DirectFired
Nominal Cooling Capacity
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Design Hot Water Flow Rate
ChillerHeater:Absorption: DoubleEffect
Nominal Cooling Capacity
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Design Hot Water Flow Rate
ChillerHeaterPerformance:Electric: EIR
Reference Cooling Mode Evaporator Capacity
Design Chilled Water Flow Rate
Design Condenser Water Flow Rate
Coil:Cooling:DX:MultiSpeed
Speed 1 Gross Rated Total Cooling Capacity
Speed 1 Gross Rated Sensible Heat Ratio
Speed 1 Rated Air Flow Rate
Speed 1 Evaporative Condenser Air Flow Rate
Speed 1 Rated Evaporative Condenser Pump Power Consumption
Speed 2 Gross Rated Total Cooling Capacity
Speed 2 Gross Rated Sensible Heat Ratio
Speed 2 Rated Air Flow Rate
Speed 2 Evaporative Condenser Air Flow Rate
Speed 2 Rated Evaporative Condenser Pump Power Consumption
Speed 3 Gross Rated Total Cooling Capacity
Speed 3 Gross Rated Sensible Heat Ratio
Speed 3 Rated Air Flow Rate
Speed 3 Evaporative Condenser Air Flow Rate
Speed 3 Rated Evaporative Condenser Pump Power Consumption
Speed 4 Gross Rated Total Cooling Capacity
Speed 4 Gross Rated Sensible Heat Ratio
Speed 4 Rated Air Flow Rate
Speed 4 Evaporative Condenser Air Flow Rate
Speed 4 Rated Evaporative Condenser Pump Power Consumption
Coil:Cooling:DX:SingleSpeed
Gross Rated Total Cooling Capacity
Gross Rated Sensible Heat Ratio
Rated Air Flow Rate
Evaporative Condenser Air Flow Rate
Evaporative Condenser Pump Rated Power Consumption
Coil:Cooling:DX:SingleSpeed: ThermalStorage
Rated Evaporator Air Flow Rate
Cooling Only Mode Rated Total Evaporator Cooling Capacity
Evaporative Condenser Pump Rated Power Consumption
Coil:Cooling:DX:TwoSpeed
High Speed Gross Rated Total Cooling Capacity
High Speed Rated Sensible Heat Ratio
High Speed Rated Air Flow Rate
Low Speed Gross Rated Total Cooling Capacity
Low Speed Gross Rated Sensible Heat Ratio
Low Speed Rated Air Flow Rate
High Speed Evaporative Condenser Air Flow Rate
High Speed Evaporative Condenser Pump Rated Power Consumption
Low Speed Evaporative Condenser Air Flow Rate
Low Speed Evaporative Condenser Pump Rated Power Consumption
Coil:Cooling:DX: VariableRefrigerantFlow
Gross Rated Total Cooling Capacity
Gross Rated Sensible Heat Ratio
Rated Air Flow Rate
Coil:Cooling:DX:VariableSpeed
Gross Rated Total Cooling Capacity At Selected Nominal Speed Level
Rated Air Flow Rate At Selected Nominal Speed Level
Evaporative Condenser Pump Rated Power Consumption
Coil:Cooling:Water
Design Water Flow Rate
Design Air Flow Rate
Design Outlet Air Temperature
Design Outlet Air Humidity Ratio
Coil:Cooling:Water: DetailedGeometry
Maximum Water Flow Rate
Tube Outside Surface Area
Total Tube Inside Area
Fin Surface Area
Minimum Airflow Area
Coil Depth
Fin Diameter
Number of Tubes per Row
Coil:Cooling:WaterToAirHeatPump: EquationFit
Rated Air Flow Rate
Rated Water Flow Rate
Gross Rated Total Cooling Capacity
Gross Rated Sensible Cooling Capacity
Coil:Cooling:WaterToAirHeatPump: VariableSpeedEquationFit
Gross Rated Total Cooling Capacity At Selected Nominal Speed Level
Rated Air Flow Rate At Selected Nominal Speed Level
Rated Water Flow Rate At Selected Nominal Speed Level
Coil:Heating:DX:MultiSpeed
Resistive Defrost Heater Capacity
Speed 1 Gross Rated Heating Capacity
Speed 1 Rated Air Flow Rate
Speed 2 Gross Rated Heating Capacity
Speed 2 Rated Air Flow Rate
Speed 3 Gross Rated Heating Capacity
Speed 3 Rated Air Flow Rate
Speed 4 Gross Rated Heating Capacity
Speed 4 Rated Air Flow Rate
Coil:Heating:DX:SingleSpeed
Gross Rated Heating Capacity
Rated Air Flow Rate
Resistive Defrost Heater Capacity
Coil:Heating:DX: VariableRefrigerantFlow
Gross Rated Heating Capacity
Rated Air Flow Rate
Coil:Heating:DX:VariableSpeed
Rated Heating Capacity At Selected Nominal Speed Level
Rated Air Flow Rate At Selected Nominal Speed Level
Resistive Defrost Heater Capacity
Coil:Heating:Electric
Nominal Capacity
Coil:Heating:Electric:MultiStage
Stage 1 Nominal Capacity
Stage 2 Nominal Capacity
Stage 3 Nominal Capacity
Stage 4 Nominal Capacity
Coil:Heating:Gas
Nominal Capacity
Coil:Heating:Gas:MultiStage
Stage 1 Nominal Capacity
Stage 2 Nominal Capacity
Stage 3 Nominal Capacity
Stage 4 Nominal Capacity
Coil:Heating:Steam
Maximum Steam Flow Rate
Coil:Heating:Water
U-Factor Times Area Value
Maximum Water Flow Rate
Rated Capacity
Coil:Heating:WaterToAirHeatPump: EquationFit
Rated Air Flow Rate
Rated Water Flow Rate
Gross Rated Heating Capacity
Coil:Heating:WaterToAirHeatPump: VariableSpeedEquationFit
Rated Heating Capacity At Selected Nominal Speed Level
Rated Air Flow Rate At Selected Nominal Speed Level
Rated Water Flow Rate At Selected Nominal Speed Level
CoilPerformance:DX:Cooling
Gross Rated Total Cooling Capacity
Gross Rated Sensible Heat Ratio
Rated Air Flow Rate
Evaporative Condenser Air Flow Rate
Evaporative Condenser Pump Rated Power Consumption
CondenserLoop
Maximum Loop Flow Rate
Controller:OutdoorAir
Minimum Outdoor Air Flow Rate
Maximum Outdoor Air Flow Rate
Controller:WaterCoil
Controller Convergence Tolerance
Maximum Actuated Flow
CoolingTower:SingleSpeed
Design Water Flow Rate
Design Air Flow Rate
Design Fan Power
Design U-Factor Times Area Value
CoolingTower:TwoSpeed
Design Water Flow Rate
High Fan Speed Air Flow Rate
High Fan Speed Fan Power
High Fan Speed U-Factor Times Area Value
CoolingTower:VariableSpeed
Design Water Flow Rate
Design Air Flow Rate
Design Fan Power
CoolingTower:VariableSpeed:Merkel
Nominal Capacity
Design Water Flow Rate
Design Air Flow Rate U-Factor Times Area Value
EvaporativeCooler:Indirect: ResearchSpecial
Secondary Fan Flow Rate
EvaporativeFluidCooler:SingleSpeed
Design Air Flow Rate
Design Air Flow Rate Fan Power
Design Air Flow Rate U-factor Times Area Value
Design Water Flow Rate
EvaporativeFluidCooler:TwoSpeed
High Fan Speed Air Flow Rate
High Fan Speed Fan Power
High Fan Speed U-factor Times Area Value
Design Water Flow Rate
Fan:ComponentModel
Maximum Flow Rate
Minimum Flow Rate
Motor Fan Pulley Ratio
Belt Maximum Torque
Maximum Motor Output Power
Maximum VFD Output Power
Fan:ConstantVolume
Maximum Flow Rate
Fan:OnOff
Maximum Flow Rate
FanPerformance:NightVentilation
Maximum Flow Rate
Fan:VariableVolume
Maximum Flow Rate
FluidCooler:SingleSpeed
Design Air Flow Rate U-factor Times Area Value
Design Water Flow Rate
Design Air Flow Rate
Design Air Flow Rate Fan Power
FluidCooler:TwoSpeed
High Fan Speed U-factor Times Area Value
Design Water Flow Rate
High Fan Speed Air Flow Rate
High Fan Speed Fan Power
Total Rated Flow Rate
Rated Power Consumption
Total Rated Flow Rate
Rated Power Consumption
HeatExchanger:AirToAir: SensibleAndLatent
Nominal Supply Air Flow Rate
HeatExchanger:FluidToFluid
Loop Demand Side Design Flow Rate
Loop Supply Side Design Flow Rate
Heat Exchanger U-Factor Times Area Value
Humidifier:Steam:Electric
Rated Power
HVACTemplate:Plant:Boiler
Capacity
HVACTemplate:Plant:Chiller
Capacity
HVACTemplate:Plant:Tower
High Speed Nominal Capacity
High Speed Fan Power
Low Speed Nominal Capacity
Low Speed Fan Power
Free Convection Capacity
HVACTemplate:System:ConstantVolume
Supply Fan Maximum Flow Rate
Heating Coil Capacity
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System: DedicatedOutdoorAir
Supply Fan Flow Rate
DX Cooling Coil Gross Rated Total Capacity
DX Cooling Coil Gross Rated Sensible Heat Ratio
Humidifier Rated Electric Power
HVACTemplate:System:DualDuct
Main Supply Fan Maximum Flow Rate
Cold Duct Supply Fan Maximum Flow Rate
Hot Duct Supply Fan Maximum Flow Rate
Heating Coil Capacity
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System:PackagedVAV
Supply Fan Maximum Flow Rate
Supply Fan Minimum Flow Rate
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heating Coil Capacity
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System:Unitary
Supply Fan Maximum Flow Rate
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heating Coil Capacity
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System:UnitaryHeatPump: AirToAir
Cooling Supply Air Flow Rate
Heating Supply Air Flow Rate
No Load Supply Air Flow Rate
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heat Pump Heating Coil Gross Rated Capacity
Supplemental Heating Coil Capacity
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System:UnitarySystem
Cooling Supply Air Flow Rate
Heating Supply Air Flow Rate
No Load Supply Air Flow Rate
DX Cooling Coil Gross Rated Total Capacity
DX Cooling Coil Gross Rated Sensible Heat Ratio
Heating Coil Gross Rated Capacity
Supplemental Heating or Reheat Coil Capacity
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System:VAV
Supply Fan Maximum Flow Rate
Supply Fan Minimum Flow Rate
Maximum Outdoor Air Flow Rate
Minimum Outdoor Air Flow Rate
Humidifier Rated Electric Power
HVACTemplate:System:VRF
Gross Rated Total Cooling Capacity
Gross Rated Heating Capacity
Resistive Defrost Heater Capacity
Water Condenser Volume Flow Rate
Evaporative Condenser Air Flow Rate
Evaporative Condenser Pump Rated Power Consumption
HVACTemplate:Zone:BaseboardHeat
Baseboard Heating Capacity
HVACTemplate:Zone:ConstantVolume
Supply Air Maximum Flow Rate
Baseboard Heating Capacity
HVACTemplate:Zone:DualDuct
Supply Air Maximum Flow Rate
Baseboard Heating Capacity
HVACTemplate:Zone:FanCoil
Supply Air Maximum Flow Rate
Baseboard Heating Capacity
Maximum Heating Air Flow Rate
Maximum Sensible Heating Capacity
Maximum Cooling Air Flow Rate
Maximum Total Cooling Capacity
HVACTemplate:Zone:PTAC
Cooling Supply Air Flow Rate
Heating Supply Air Flow Rate
No Load Supply Air Flow Rate
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heating Coil Capacity
Baseboard Heating Capacity
HVACTemplate:Zone:PTHP
Cooling Supply Air Flow Rate
Heating Supply Air Flow Rate
No Load Supply Air Flow Rate
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heat Pump Heating Coil Gross Rated Capacity
Supplemental Heating Coil Capacity
Baseboard Heating Capacity
HVACTemplate:Zone:Unitary
Supply Air Maximum Flow Rate
Baseboard Heating Capacity
HVACTemplate:Zone:VAV
Supply Air Maximum Flow Rate
Baseboard Heating Capacity
HVACTemplate:Zone:VAV:FanPowered
Primary Supply Air Maximum Flow Rate
Primary Supply Air Minimum Flow Fraction
Secondary Supply Air Maximum Flow Rate
Parallel Fan On Flow Fraction
Baseboard Heating Capacity
HVACTemplate:Zone:VAV:HeatAndCool
Supply Air Maximum Flow Rate
Baseboard Heating Capacity
HVACTemplate:Zone:VRF
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate When No Cooling is Needed
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Heating is Needed
Outdoor Air Flow Rate During Cooling Operation
Outdoor Air Flow Rate During Heating Operation
Outdoor Air Flow Rate When No Cooling or Heating is Needed
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heat Pump Heating Coil Gross Rated Capacity
Baseboard Heating Capacity
HVACTemplate:Zone: WaterToAirHeatPump
Cooling Supply Air Flow Rate
Heating Supply Air Flow Rate
No Load Supply Air Flow Rate
Cooling Coil Gross Rated Total Capacity
Cooling Coil Gross Rated Sensible Heat Ratio
Heat Pump Heating Coil Gross Rated Capacity
Supplemental Heating Coil Capacity
Baseboard Heating Capacity
PlantComponent:TemperatureSource
Design Volume Flow Rate
PlantEquipmentOperation: ComponentSetpoint
Component 1 Flow Rate
Component 2 Flow Rate
Component 3 Flow Rate
Component 4 Flow Rate
Component 5 Flow Rate
Component 6 Flow Rate
Component 7 Flow Rate
Component 8 Flow Rate
Component 9 Flow Rate
Component 10 Flow Rate
PlantLoop
Maximum Loop Flow Rate
Pump:ConstantSpeed
Rated Flow Rate
Rated Power Consumption
Pump:VariableSpeed
Rated Flow Rate
Rated Power Consumption
Pump:VariableSpeed:Condensate
Rated Flow Rate
Rated Power Consumption
Sizing:System
Design Outdoor Air Flow Rate
SolarCollector:FlatPlate: PhotovoltaicThermal
Design Flow Rate
ThermalStorage:ChilledWater:Mixed
Use Side Design Flow Rate
Source Side Design Flow Rate
ThermalStorage:ChilledWater: Stratified
Use Side Design Flow Rate
Source Side Design Flow Rate
UnitarySystemPerformance:HeatPump: Multispeed
Speed 1 Supply Air Flow Ratio During Heating Operation
Speed 1 Supply Air Flow Ratio During Cooling Operation
Speed 2 Supply Air Flow Ratio During Heating Operation
Speed 2 Supply Air Flow Ratio During Cooling Operation
Speed 3 Supply Air Flow Ratio During Heating Operation
Speed 3 Supply Air Flow Ratio During Cooling Operation
Speed 4 Supply Air Flow Ratio During Heating Operation
Speed 4 Supply Air Flow Ratio During Cooling Operation
WaterHeater:Mixed
Tank Volume
Heater Maximum Capacity
Use Side Design Flow Rate
Source Side Design Flow Rate
WaterHeater:Stratified
Tank Volume
Tank Height
Heater 1 Capacity
Use Side Design Flow Rate
Source Side Design Flow Rate
ZoneHVAC:Baseboard:Convective: Electric
Nominal Capacity
ZoneHVAC:Baseboard:Convective: Water
U-Factor Times Area Value
Maximum Water Flow Rate
Nominal Capacity
Maximum Steam Flow Rate
Rated Capacity
Maximum Water Flow Rate
ZoneHVAC:EnergyRecoveryVentilator
Supply Air Flow Rate
Exhaust Air Flow Rate
ZoneHVAC:EvaporativeCoolerUnit
Design Supply Air Flow Rate
ZoneHVAC:FourPipeFanCoil
Maximum Supply Air Flow Rate
Maximum Outdoor Air Flow Rate
Maximum Cold Water Flow Rate
Maximum Hot Water Flow Rate
Maximum Power Input
Maximum Heating Air Flow Rate
Maximum Sensible Heating Capacity
Maximum Cooling Air Flow Rate
Maximum Total Cooling Capacity
Maximum Electrical Power to Panel
Hydronic Tubing Length
Maximum Hot Water Flow
Maximum Cold Water Flow
ZoneHVAC:OutdoorAirUnit
Outdoor Air Flow Rate
Exhaust Air Flow Rate
ZoneHVAC: PackagedTerminalAirConditioner
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Needed
Outdoor Air Flow Rate During Cooling Operation
Outdoor Air Flow Rate During Heating Operation
Outdoor Air Flow Rate When No Cooling or Heating is Needed
ZoneHVAC:PackagedTerminalHeatPump
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Needed
Outdoor Air Flow Rate During Cooling Operation
Outdoor Air Flow Rate During Heating Operation
Outdoor Air Flow Rate When No Cooling or Heating is Needed
Maximum Supply Air Temperature from Supplemental Heater
ZoneHVAC:TerminalUnit: VariableRefrigerantFlow
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate When No Cooling is Needed
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Heating is Needed
Outdoor Air Flow Rate During Cooling Operation
Outdoor Air Flow Rate During Heating Operation
Outdoor Air Flow Rate When No Cooling or Heating is Needed
ZoneHVAC:UnitHeater
Maximum Supply Air Flow Rate
Maximum Hot Water or Steam Flow Rate
ZoneHVAC:UnitVentilator
Maximum Supply Air Flow Rate
Minimum Outdoor Air Flow Rate
Maximum Outdoor Air Flow Rate
ZoneHVAC:VentilatedSlab
Maximum Air Flow Rate
Minimum Outdoor Air Flow Rate
Maximum Outdoor Air Flow Rate
ZoneHVAC:WaterToAirHeatPump
Supply Air Flow Rate During Cooling Operation
Supply Air Flow Rate During Heating Operation
Supply Air Flow Rate When No Cooling or Heating is Needed
Outdoor Air Flow Rate During Cooling Operation
Outdoor Air Flow Rate During Heating Operation
Outdoor Air Flow Rate When No Cooling or Heating is Needed
Maximum Supply Air Temperature from Supplemental Heater
ZoneHVAC:WindowAirConditioner
Maximum Supply Air Flow Rate
Maximum Outdoor Air Flow Rate

: Details of Autosizable Objects/Fields

There are 3 places in the input where the user can impose sizing factors.

In Sizing Parameters (object: Sizing:Parameters), the user can specify an over-all sizing factor. This factor is applied to all the zone design loads and air flow rates resulting from the zone sizing calculations.

In Zone Sizing (object: Sizing:Zone), the user can specify a sizing factor for a specific zone. The factor is applied to the calculated zone design loads and air flow rates for the zone named in the Sizing:Zone object. This sizing factor overrides the global sizing factor. That is, a zone sizing factor, if specified, replaces the global sizing factor for the named zone.

For some plant components (basically all central chillers, boilers and cooling towers) the user can specify a sizing factor that modifies the autosized component capacity and flow rates. These factors are applied after the application of global or zone sizing factors. They are primarily used to split the design load between multiple components. These sizing factors can change the autosizing of the associated loops and pumps. The following rules are followed the effect of plant component sizing factors on loops and pumps.

For supply side branches, the sizing factors of all components in series on the branch are summed and the result becomes the branch sizing factor. If there is a branch pump its autosized design flow rate is multiplied by the branch sizing factor.

For each loop, if the average of the branch sizing factors is less than 1, the loop sizing factor is set equal to the sum of the branch sizing factors. If the average is greater than 1, the loop sizing factor is set equal to the maximum of the branch sizing factors. The loop sizing factor is applied to the loop design flow rate (if autosized) and to the loop pump flow rate (if autosized).

### Mixing User-Specified and Autosized Inputs[LINK]

Mixed user-specified and autosized inputs can be successfully used if the following points and suggestions are followed.

Each component is autosized independently. Thus user input for a flow rate in one component will have no effect on other components’ autosized flow rates. For instance, specifying the chilled water loop pump’s rated flow rate will have no effect on the autosizing of the chiller’s design evaporator flow rate or on the plant loop’s autosized maximum loop flow rate.

Within a component it is best to autosize all inputs are enter specified values for all inputs. For example, in a chiller, if only the nominal capaciity is user-specified, the autosized chilled water flow rate may not be consistent with the specified capacity.

Sizing information flows only from the sizing objects to the components. The sizing calculations have no knowledge of user-specified values in a component. The only exception to this rule is that plant loop sizing will collect all component design water flow rates whether autosized or user-specified.

If the user wants to specify a zone or system air flow rate it should be done using the Sizing:Zone and Sizing:System objects rather than done in the individual components.

The plant loop flow rates are sized from the total design demand of the components connected to each loop. The components demanding water need not be autosized for the plant loop autosizing to work successfully. So the user could specify all the air side components and autosize all the plant loops and plant components. Or specify the chilled water loop flow rate, chilled water pump inputs and chiller inputs and let the condenser loop and tower autosize.

The results of the component autosizing calculations are reported on the eplusout.eio file. For each component field that has been autosized the object type, object name, field description with unit, and value are printed out as comma separated data on a line beginning with Component Sizing. Examples of this are shown in the Output Details and Examples document.

The complete list of objects that have autosized fields is shown in the following table. Note that spaces may be inserted in object names to facilitate readability.

Complete list of Objects with autosized Fields
Object Name Object Name
AirConditioner:VariableRefrigerantFlow AirLoopHVAC
AirLoopHVAC:Unitary:Furnace:HeatCool AirLoopHVAC:Unitary:Furnace:HeatOnly
AirLoopHVAC:UnitaryHeatCool AirLoopHVAC:UnitaryHeatCool: VAVChangeoverBypass
AirLoopHVAC:UnitaryHeatOnly AirLoopHVAC:UnitaryHeatPump:AirToAir
AirLoopHVAC:UnitaryHeatPump:AirToAir: MultiSpeed AirLoopHVAC:UnitaryHeatPump:WaterToAir
AirLoopHVAC:UnitarySystem AirTerminal:DualDuct:ConstantVolume
AirTerminal:DualDuct:VAV AirTerminal:DualDuct:VAV:OutdoorAir
AirTerminal:SingleDuct:ConstantVolume: CooledBeam AirTerminal:SingleDuct:ConstantVolume: FourPipeInduction
AirTerminal:SingleDuct:ConstantVolume: Reheat AirTerminal:SingleDuct:ParallelPIU: Reheat
AirTerminal:SingleDuct:SeriesPIU: Reheat AirTerminal:SingleDuct:Uncontrolled
AirTerminal:SingleDuct:VAV: HeatAndCool:NoReheat AirTerminal:SingleDuct:VAV: HeatAndCool:Reheat
AirTerminal:SingleDuct:VAV:NoReheat AirTerminal:SingleDuct:VAV:Reheat
AirTerminal:SingleDuct:VAV:Reheat: VariableSpeedFan Boiler:HotWater
Boiler:Steam Branch
Chiller:Absorption Chiller:Absorption:Indirect
Chiller:CombustionTurbine Chiller:ConstantCOP
Chiller:Electric Chiller:Electric:EIR
Chiller:Electric:ReformulatedEIR Chiller:EngineDriven
ChillerHeater:Absorption:DirectFired ChillerHeater:Absorption:DoubleEffect
ChillerHeaterPerformance:Electric:EIR Coil:Cooling:DX:MultiSpeed
Coil:Cooling:DX:SingleSpeed Coil:Cooling:DX:SingleSpeed: ThermalStorage
Coil:Cooling:DX:TwoSpeed Coil:Cooling:DX: VariableRefrigerantFlow
Coil:Cooling:DX:VariableSpeed Coil:Cooling:Water
Coil:Cooling:Water:DetailedGeometry Coil:Cooling:WaterToAirHeatPump: EquationFit
Coil:Cooling:WaterToAirHeatPump: VariableSpeedEquationFit Coil:Heating:DX:MultiSpeed
Coil:Heating:DX:SingleSpeed Coil:Heating:DX: VariableRefrigerantFlow
Coil:Heating:DX:VariableSpeed Coil:Heating:Electric
Coil:Heating:Electric:MultiStage Coil:Heating:Gas
Coil:Heating:Gas:MultiStage Coil:Heating:Steam
Coil:Heating:Water Coil:Heating:WaterToAirHeatPump: EquationFit
Coil:Heating:WaterToAirHeatPump: VariableSpeedEquationFit CoilPerformance:DX:Cooling
CondenserLoop Controller:OutdoorAir
Controller:WaterCoil CoolingTower:SingleSpeed
CoolingTower:TwoSpeed CoolingTower:VariableSpeed
CoolingTower:VariableSpeed:Merkel EvaporativeCooler:Indirect: ResearchSpecial
EvaporativeFluidCooler:SingleSpeed EvaporativeFluidCooler:TwoSpeed
Fan:ComponentModel Fan:ConstantVolume
Fan:OnOff FanPerformance:NightVentilation
Fan:VariableVolume FluidCooler:SingleSpeed
HeatExchanger:FluidToFluid Humidifier:Steam:Electric
HVACTemplate:Plant:Boiler HVACTemplate:Plant:Chiller
HVACTemplate:Plant:Tower HVACTemplate:System:ConstantVolume
HVACTemplate:System: DedicatedOutdoorAir HVACTemplate:System:DualDuct
HVACTemplate:System:PackagedVAV HVACTemplate:System:Unitary
HVACTemplate:System:UnitaryHeatPump: AirToAir HVACTemplate:System:UnitarySystem
HVACTemplate:System:VAV HVACTemplate:System:VRF
HVACTemplate:Zone:BaseboardHeat HVACTemplate:Zone:ConstantVolume
HVACTemplate:Zone:DualDuct HVACTemplate:Zone:FanCoil
HVACTemplate:Zone:PTHP HVACTemplate:Zone:Unitary
HVACTemplate:Zone:VAV HVACTemplate:Zone:VAV:FanPowered
HVACTemplate:Zone:VAV:HeatAndCool HVACTemplate:Zone:VRF
HVACTemplate:Zone:WaterToAirHeatPump PlantComponent:TemperatureSource
PlantEquipmentOperation: ComponentSetpoint PlantLoop
Pump:ConstantSpeed Pump:VariableSpeed
Pump:VariableSpeed:Condensate Sizing:System
SolarCollector:FlatPlate: PhotovoltaicThermal ThermalStorage:ChilledWater:Mixed
ThermalStorage:ChilledWater:Stratified UnitarySystemPerformance:HeatPump: Multispeed
WaterHeater:Mixed WaterHeater:Stratified
ZoneHVAC:Baseboard:Convective:Electric ZoneHVAC:Baseboard:Convective:Water
ZoneHVAC:EvaporativeCoolerUnit ZoneHVAC:FourPipeFanCoil
ZoneHVAC:OutdoorAirUnit ZoneHVAC: PackagedTerminalAirConditioner
ZoneHVAC:PackagedTerminalHeatPump ZoneHVAC:TerminalUnit: VariableRefrigerantFlow
ZoneHVAC:UnitHeater ZoneHVAC:UnitVentilator
ZoneHVAC:VentilatedSlab ZoneHVAC:WaterToAirHeatPump
ZoneHVAC:WindowAirConditioner

: Complete list of Objects with autosized Fields

### User or External Zone Design Flow Rate Inputs[LINK]

In EnergyPlus the autosizing calculations start with a calculation of the zone design air flow rates using zone by zone design day simulations. The resulting zone design air flow rates and daily air flow sequences are used in the subsequent HVAC and central plant air and fluid flow design calculations and in the component autosizing calculations. The user can override or change the calculated zone design air flow rates in several ways.

1. The user can enter a value for Sizing Factor in the Sizing:Parameters object (see description below).
2. The user can specify a zone level Zone Sizing Factor in each Sizing:Zone object.
3. For each zone the user can input a Cooling Design Air Flow Rate and/or a Heating Design Air Flow Rate (and specify Cooling Design Air Flow Method = Flow/Zone and Heating Design Air Flow Method = Flow/Zone). These user inputs override the calculated values. The program divides the user input cooling or heating design air flow rate by the calculated values and uses the result as a zone sizing factor to multiply all the elements in the design heating and cooling air flow and load sequences. From this point the design calculations proceed as usual.

### User or External System Design Flow Rate Inputs[LINK]

Using the results of the zone design air flow rate calculation (including any user input or altered flow rates) EnergyPlus proceeds to calculate central air system flow rates and cooling and heating loads. The results of this calculation can be overridden in the following way.

For each system (AirLoopHVAC), in the corresponding Sizing:System object, specify Cooling Design Air Flow Method to be Flow/System and input a value for Cooling Design Air Flow Rate. **Similarly for heating specify Heating Design Air Flow Method to be Flow/System and input a value for Heating Design Air Flow Rate.

This object allows for the outdoor air requirements to be defined in a common location for use by other objects. This object may be referenced by name from other objects (e.g., VAV terminal units) as required to identify an outdoor air quantity for use by that object. Note that a zone name Is not included as an input to this zone outdoor air definition and the number of people in a zone, zone floor area, and zone volume can only be determined after this object has been referenced by another. A single zone outdoor air definition may be referenced by multiple objects to specify that the same outdoor air requirements are used by those objects or multiple zone outdoor air objects may be defined and referenced by other objects as needed. If multiple zone outdoor air definitions are used, each outdoor air definition must have a unique name.

Unique identifying name. Any reference to this name by other objects will denote that the following outdoor air requirements will be used.

The input must be either Flow/Person, Flow/Area, Flow/Zone, AirChanges/Hour, Sum, or Maximum. Flow/Person means the program will use the input from the field Outdoor Air Flow per Person and the actual zone occupancy to calculate a zone outdoor air flow rate. Flow/Area means that the program will use the input from the field Outdoor Air Flow per Zone Floor Area and the actual zone floor area as the zone outdoor air flow rate. Flow/Zone means that the program will use the input of the field Outdoor Air Flow per Zone as the zone outdoor air flow rate. AirChanges/Hour means that the program will use the input from the field Air Changes per Hour and the actual zone volume (divided by 3600 seconds per hour) as the zone outdoor air flow rate. Sum means that the flows calculated from the fields Outdoor Air Flow per Person, Outdoor Air Flow per Area, Outdoor Air Flow per Zone, and Air Changes per Hour (using the associated conversions to m3/s for each field) will be added to obtain the zone outdoor air flow rate. Maximum means that the maximum flow derived from Outdoor Air Flow per Person, Outdoor Air Flow per Area, Outdoor Air Flow per Zone, and Air Changes per Hour (using the associated conversions to m3/s for each field) will be used as the zone outdoor air flow rate. The default is Flow/Person.

#### Field: Outdoor Air Flow per Person[LINK]

The design outdoor air volume flow rate per person for this zone in cubic meters per second per person. The default is 0.00944 (20 cfm per person). An outdoor air flow rate is calculated based on the total number of people for all People statements assigned to the zone. Occupancy schedule values are not applied during sizing calculations and are applied during the remainder of the simulation. This input is used if Outdoor Air Method is one of Outdoor Air Flow per Person, Sum, or Maximum.

#### Field: Outdoor Air Flow per Zone Floor Area[LINK]

The design outdoor air volume flow rate per square meter of floor area (units are m3/s-m2). This input is used if Outdoor Air Method is Flow/Area, Sum or Maximum. The default value for this field is 0.

#### Field: Outdoor Air Flow per Zone[LINK]

The design outdoor air flow rate for this zone in cubic meters per second. This input field is used if Outdoor Air Method is Flow/Zone, Sum or Maximum. The default value for this field is 0.

#### Field: Outdoor Air Flow Changes per Hour[LINK]

The design outdoor air volume flow rate in air changes per hour. This factor is used along with the Zone Volume and converted to cubic meters per second. This input field is used if Outdoor Air Method is AirChanges/Hour, Sum or Maximum. The default value for this field is 0.

#### Field: Outdoor Air Flow Rate Fraction Schedule Name[LINK]

This field is the name of schedule that defines how outdoor air requirements change over time. The field is optional. If used, then the schedule values are multiplied by the outdoor air flow rate defined by the previous fields. The schedule values must be between 0 and 1, inclusive.

An IDF example:

DesignSpecification:OutdoorAir
Sum,                   !- Outdoor Air Method
0.00944,               !- Outdoor Air Flow per Person {m3/s}
0.00305,               !- Outdoor Air Flow per Zone Floor Area {m3/s-m2}
,                      !- Outdoor Air Flow per Zone {m3/s}
,                      !- Outdoor Air Flow Air Changes per Hour
OARequirements Sched;  !- Outdoor Air Flow Rate Fraction Schedule Name

Schedule:Compact,
OARequirements Sched,    !- Name
Any Number,              !- Schedule Type Limits Name
Through: 12/31,          !- Field 1
For: Weekdays SummerDesignDay WinterDesignDay,  !- Field 2
Until: 24:00, 1.0,       !- Field 4
For: AllOtherDays,       !- Field 5
Until: 24:00, 0.5;       !- Field 7

This object is used to describe the air distribution effectiveness and fraction of secondary recirculation air (return air not directly mixed with outdoor air) of a zone. It is referenced by the Sizing:Zone and Controller:MechanicalVentilation objects.

The unique user assigned name for an instance of this object. Any other object referencing this object will use this name.

#### Field: Zone Air Distribution Effectiveness in Cooling Mode[LINK]

The positive numeric input for this field is the zone air distribution effectiveness when the zone is in cooling mode. Default value of this field is 1.0. ASHRAE Standard 62.1-2010 provides typical values.

#### Field: Zone Air Distribution Effectiveness in Heating Mode[LINK]

The positive numeric input for this field is the zone air distribution effectiveness when the zone is in heating mode. Default value of this field is 1.0. ASHRAE Standard 62.1-2010 provides typical values as follows:

#### Field: Zone Air Distribution Effectiveness Schedule Name[LINK]

This optional field input points to a schedule with values of zone air distribution effectiveness. It provides a more flexible way of specifying zone air distribution effectiveness if it changes with time and/or system operating status and controls. If the schedule is specified, the zone air distribution effectiveness in cooling mode and heating mode will be ignored.

#### Field: Zone Secondary Recirculation Fraction[LINK]

The non-negative numeric input for this field is the fraction of a zone’s recirculation air that does not directly mix with the outdoor air. The zone secondary recirculation fraction Er is determined by the designer based on system configuration. For plenum return systems with secondary recirculation (e.g., fan-powered VAV with plenum return) Er is usually less than 1.0, although values may range from 0.1 to 1.2 depending upon the location of the ventilation zone relative to other zones and the air handler. For ducted return systems with secondary recirculation (e.g., fan-powered VAV with ducted return), Er is typically 0.0, while for those with system-level recirculation (e.g, dual-fan dual-duct systems with ducted return) Er is typically 1.0. For other system types, Er is typically 0.75. Minimum is 0.0, and default is 0.0 for single-path systems (also to maintain backward compatibility). For parallel fan-powered VAV systems, the secondary ventilation path only functions (Er > 0.0) when the fans in the VAV boxes operate, which is during heating. The local ventilation path and the benefits of secondary recirculation disappear during cooling, when the local parallel fans are off (Er = 0.0).

An example of this in an IDF context is shown:

DesignSpecification:ZoneAirDistribution,
1,                       !- Zone Air Distribution Effectiveness in Cooling Mode {dimensionless}
1,                       !- Zone Air Distribution Effectiveness in Heating Mode {dimensionless}
;                        !- Zone Air Distribution Effectiveness Schedule Name

This object allows the user to specify global heating and cooling sizing ratios. These ratios will be applied at the zone level to all of the zone heating and cooling loads and air flow rates. These new loads and air flow rates are then used to calculate the system level flow rates and capacities and are used in all component sizing calculations.

The user can also specify the width (in load timesteps) of a moving average window which can be used to smooth the calculated zone design flow sequences. The use of this parameter is described below.

The global heating sizing ratio applied to all of the zone design heating loads and air flow rates.

The global cooling sizing ratio applied to all of the zone design cooling loads and air flow rates

#### Field: Timesteps in Averaging Window[LINK]

The number of load timesteps in the zone design flow sequence averaging window. The default is 1, in which case the calculated zone design flow rates are averaged over the load timestep.

The zone design air flow rate calculation is performed assuming a potentially infinite supply of heating or cooling air at a fixed temperature. Thus the calculated design air flow rate will always be able to meet any load or change in load no matter how large or abrupt. In reality air flow rates are limited by duct sizes and fan capacities. The idealized zone design flow calculation may result in unrealistically large flow rates, especially if the user is performing the sizing calculations using thermostat schedules with night setup or setback. The calculated zone design flow rates are always averaged over the load timestep. The user may want to perform a broader average to mitigate the effect of thermostat setup and setback and prevent the warm up or cool down flow rates from dominating the design flow rate calculation.. Specifying the width of the averaging window allows the user to do this.

For example, if the load calculation timestep is 15 minutes and the user specifies the Timesteps in Averaging Window to be 4, the zone design air flows will be averaged over a time period of 1 hour. Specifying 8 would result in averaging over a 2 hour period.

The sizing factors and the averaging window size are reported out on the eplusout.eio file. An example is:

! <Load Timesteps in Zone Design Calculation Averaging Window>, Value
Timesteps in Averaging Window,    1
! <Heating Sizing Factor Information>, Sizing Factor ID, Value
Heating Sizing Factor, Global,   1.3000
Heating Sizing Factor, Zone SPACE1-1,   1.3000
Heating Sizing Factor, Zone SPACE2-1,   1.3000
Heating Sizing Factor, Zone SPACE3-1,   1.3000
Heating Sizing Factor, Zone SPACE4-1,   1.3000
Heating Sizing Factor, Zone SPACE5-1,   1.3000
! <Cooling Sizing Factor Information>, Sizing Factor ID, Value
Cooling Sizing Factor, Global,   1.3000
Cooling Sizing Factor, Zone SPACE1-1,   1.3000
Cooling Sizing Factor, Zone SPACE2-1,   1.3000
Cooling Sizing Factor, Zone SPACE3-1,   1.3000
Cooling Sizing Factor, Zone SPACE4-1,   1.3000
Cooling Sizing Factor, Zone SPACE5-1,   1.3000

As described early in the document (see: EnergyPlus Output Processing), the user may select the “style” for the sizing result files (epluszsz., eplusssz.). This object applies to all sizing output files.

OutputControl:Sizing:Style,
\memo default style for the Sizing output files is comma -- this works well for
\memo importing into spreadsheet programs such as Excel(tm) but not so well for word
\memo processing progams -- there tab may be a better choice.  fixed puts spaces between
\memo the "columns"
\unique-object
A1; \field Column Separator
\required-field
\type choice
\key Comma
\key Tab
\key Fixed

For this field, the desired separator for columns is entered. “Comma” creates comma separated fields/columns in the outputs (eplus.csv files are created). “Tab” creates tab separated fields/columns in the outputs (eplus.tab files are created). “Fixed” creates space separated fields/columns in the outputs (eplus.txt files are created) but these are not necessarily lined up for easy printing.

Note that both tab and comma separated files easily import into Excel™ or other spreadsheet programs. The tab delimited files can also be viewed by text editors, word processing programs and easily converted to “tables” within those programs.

The Sizing:Zone object provides the data needed to perform a zone design air flow calculation for a single zone. This calculation assumes a variable amount of supply air at a fixed temperature and humidity. The information needed consists of the zone inlet supply air conditions: temperature and humidity ratio for heating and cooling. The calculation is done for every design day included in the input. The maximum cooling load and air flow and the maximum heating load and air flow are then saved for the system level design calculations and for the component automatic sizing calculations.

The Sizing:Zone object is also the place where the user can specify the design outdoor air flow rate by referencing the name of a design specification outdoor air object. This can be specified in a number of ways (ref. DesignSpecification:OutdoorAir).This data is saved for use in the system sizing calculation or for sizing zone components that use outdoor air.

The user can also place limits on the heating and design cooling air flow rates. See Heating Design Air Flow Method and Cooling Design Air Flow Method below and the explanations of the various heating and cooling flow input fields.

The name of the Zone corresponding to this Sizing:Zone object. This is the zone for which the design air flow calculation will be made using the input data of this Sizing:Zone Object.

#### Field: Zone Cooling Design Supply Air Temperature Input Method[LINK]

The input must be either SupplyAirTemperature or TemperatureDifference. SupplyAirTemperature means that the user inputs from the fields of Zone Cooling Design Supply Air Temperature will be used to determine the zone cooling design air flow rates. TemperatureDifference means that the user inputs from the fields of Zone Cooling Design Supply Air Temperature Difference will be used to determine the zone cooling design air flow rates.

#### Field: Zone Cooling Design Supply Air Temperature[LINK]

The supply air temperature in degrees Celsius for the zone cooling design air flow rate calculation. Air is supplied to the zone at this temperature during the cooling design day simulation, The zone load is met by varying the zone air flow rate. The maximum zone flow rate is saved as the zone cooling design air flow rate. This field is only used when Zone Cooling Design Supply Air Temperature Input Method = SupplyAirTemperature.

#### Field: Zone Cooling Design Supply Air Temperature Difference[LINK]

The temperature difference between cooling design supply air temperature and room air temperature in degrees Celsius for the zone cooling design air flow rate calculation. Air is supplied to the zone at this temperature during the cooling design day simulation. The zone load is met by varying the zone air flow rate. The maximum zone flow rate is saved as the zone cooling design air flow rate. This field is only used when Zone Cooling Design Supply Air Temperature Input Method = TemperatureDifference.

#### Field: Zone Heating Design Supply Air Temperature Input Method[LINK]

The input must be either SupplyAirTemperature or TemperatureDifference. SupplyAirTemperature means that the user inputs from the fields of Zone Heating Design Supply Air Temperature will be used to determine the zone heating design air flow rates. TemperatureDifference means that the user inputs from the fields of Zone Heating Design Supply Air Temperature Difference will be used to determine the zone heating design air flow rates.

#### Field: Zone Heating Design Supply Air Temperature[LINK]

The supply air temperature in degrees Celsius for the zone heating design air flow rate calculation. Air is supplied to the zone at this temperature during the heating design day simulation, The zone load is met by varying the zone air flow rate. The maximum zone flow rate is saved as the zone heating design air flow rate. This field is only used when Zone Heating Design Supply Air Temperature Input Method = SupplyAirTemperature.

#### Field: Zone Heating Design Supply Air Temperature Difference[LINK]

The temperature difference between heating design supply air temperature and room air temperature in degrees Celsius for the zone heating design air flow rate calculation. Air is supplied to the zone at this temperature during the heating design day simulation. The zone load is met by varying the zone air flow rate. The maximum zone flow rate is saved as the zone heating design air flow rate. This field is only used when Zone Heating Design Supply Air Temperature Input Method = TemperatureDifference.

#### Field: Zone Cooling Design Supply Air Humidity Ratio[LINK]

The humidity ratio in kilograms of water per kilogram of dry air of the supply air in the zone cooling design air flow rate calculation.

#### Field: Zone Heating Design Supply Air Humidity Ratio[LINK]

The humidity ratio in kilograms of water per kilogram of dry air of the supply air in the zone heating design air flow rate calculation.

#### Field: Design Specification Outdoor Air Object Name[LINK]

This alpha field specifies the name of a DesignSpecification:OutdoorAir object which specifies the design outdoor air flow rate for the zone.

#### Field: Zone Heating Sizing Factor[LINK]

This input is a zone level heating sizing ratio. The zone design heating air flow rates and loads will be multiplied by the number input in this field. This input overrides the building level sizing factor input in the Sizing:Parameters object. And, of course, if this field is blank or zero, the global heating sizing factor from the Sizing:Parameters object is used.

#### Field: Zone Cooling Sizing Factor[LINK]

This input is a zone level cooling sizing ratio. The zone design cooling air flow rates and loads will be multiplied by the number input in this field. This input overrides the building level sizing factor input in the Sizing:Parameters object. And, of course, if this field is blank or zero, the global cooling sizing factor from the Sizing:Parameters object is used.

#### Field: Cooling Design Air Flow Method[LINK]

The input must be either Flow/Zone, DesignDay, or DesignDayWithLimit. Flow/Zone means that the program will use the input of the field Cooling Design Air Flow Rate as the zone design cooling air flow rate. DesignDay means the program will calculate the zone design cooling air flow rate using the Sizing:Zone input data and a design day simulation without imposing any limits other than those set by the minimum outside air requirements. DesignDayWithLimit means that the maximum from Cooling Minimum Air Flow per Zone Floor Area and Cooling Minimum Air Flow will set a lower limit on the **design maximum cooling air flow rate. The default method is DesignDay: i.e., the program uses the calculated design values subject to ventilation requirements.

#### Field: Cooling Design Air Flow Rate[LINK]

The design zone cooling air flow rate in cubic meters per second. This input is used if Cooling Design Air Flow Method is specified as Flow/Zone. This value will be multiplied by the global or zone sizing factor and by zone multipliers.

#### Field: Cooling Minimum Air Flow per Zone Floor Area[LINK]

The minimum zone cooling volumetric flow rate per square meter (units are m3/s-m2). This field is used when Cooling Design Air Flow Method is specified as DesignDayWithLimit. In this case it sets a lower bound on the zone design cooling air flow rate. In all cases the maximum flow derived from Cooling Minimum Air Flow per Zone Floor Area, Cooling Minimum Air Flow, and Cooling Minimum Air Flow Fraction is used to set a minimum supply air flow rate for the zone for VAV systems. The default is .000762, corresponding to .15 cfm/ft2. The applicable sizing factor is not applied to this value.

#### Field: Cooling Minimum Air Flow[LINK]

The minimum zone cooling volumetric flow rate in m3/s. This field is used when Cooling Design Air Flow Method is specified as DesignDayWithLimit. In this case it sets a lower bound on the zone design cooling air flow rate. In all cases the maximum flow derived from Cooling Minimum Air Flow per Zone Floor Area, Cooling Minimum Air Flow, and Cooling Minimum Air Flow Fraction is used to set a minimum supply air flow rate for the zone for VAV systems. The default is zero. The applicable sizing factor is not applied to this value.

#### Field: Cooling Minimum Air Flow Fraction[LINK]

The minimum zone design cooling volumetric flow rate expressed as a fraction of the zone design cooling volumetric flow rate. . In all cases the maximum flow derived from Cooling Minimum Air Flow per Zone Floor Area, Cooling Minimum Air Flow, and Cooling Minimum Air Flow Fraction is used to set a minimum supply air flow rate for the zone for VAV systems. The default is zero. This input is currently used in sizing the fan minimum flow rate. It does not currently affect other component autosizing.

#### Field: Heating Design Air Flow Method[LINK]

The input must be either Flow/Zone, DesignDay, or DesignDayWithLimit. Flow/Zone means that the program will use the input of the field Heating Design Air Flow Rate as the zone design heating air flow rate. DesignDay means the program will calculate the zone design heating air flow rate using the Sizing:Zone input data and a design day simulation without imposing any limits other than those set by the minimum outside air requirements. DesignDayWithLimit means that the maximum from Heating Maximum Air Flow per Zone Floor Area and Heating Maximum Air Flow will set a lower limit on the **design maximum heating air flow rate. The default method is DesignDay: i.e., the program uses the calculated design values subject to ventilation requirements.

#### Field: Heating Design Air Flow Rate[LINK]

The design zone heating air flow rate in cubic meters per second. This input is used if Heating Design Air Flow Method is specified as Flow/Zone. This value will be multiplied by the global or zone sizing factor and by zone multipliers.

#### Field: Heating Maximum Air Flow per Zone Floor Area[LINK]

The maximum zone heating volumetric flow rate per square meter (units are m3/s-m2). This field is used when Heating Design Air Flow Method is specified as DesignDayWithLimit. In this case it sets an upper bound on the zone design heating air flow rate. For this and the next two input fields, the maximum flow derived from Heating Maximum Air Flow per Zone Floor Area, Heating Maximum Air Flow, and Heating Maximum Air Flow Fraction is used to set a maximum heating supply air flow rate for the zone for VAV systems. The default is .002032, corresponding to .40 cfm/ft2. If the maximum heating design flow rate calculated using these input fields is greater than the design heating flow rate calculated during sizing, these input fields have no impact on sizing. It may be more appropriate to select only one of these three fields to calculate the maximum heating design flow rate (i.e., if one ore more of these three fields is 0, it will not be used in calculating the maximum heating design flow rate).

#### Field: Heating Maximum Air Flow[LINK]

The maximum zone heating volumetric flow rate in m3/s. This field is used when Heating Design Air Flow Method is specified as DesignDayWithLimit. In this case it sets an upper bound on the zone design heating air flow rate. For this field and the two input fields just prior to and after this field,,the maximum flow derived from Heating Maximum Air Flow per Zone Floor Area, Heating Maximum Air Flow, and Heating Maximum Air Flow Fraction is used to set a maximum heating supply air flow rate for the zone for VAV systems. The default is .1415762, corresponding to 300 cfm. If the maximum heating design flow rate calculated using these input fields is greater than the design heating flow rate calculated during sizing, these input fields have no impact on sizing. It may be more appropriate to select only one of these three fields to calculate the maximum heating design flow rate (i.e., if one ore more of these three fields is 0, it will not be used in calculating the maximum heating design flow rate).

#### Field: Heating Maximum Air Flow Fraction[LINK]

The maximum zone design heating volumetric flow rate expressed as a fraction of the zone design cooling volumetric flow rate. For this and the previous two input fields, the maximum flow derived from Heating Maximum Air Flow per Zone Floor Area, Heating Maximum Air Flow, and Heating Maximum Air Flow Fraction is used to set a maximum heating supply air flow rate for the zone for VAV systems. The default is 0.3. If the maximum heating design flow rate calculated using these input fields is greater than the design heating flow rate calculated during sizing, these input fields have no impact on sizing. It may be more appropriate to select only one of these three fields to calculate the maximum heating design flow rate (i.e., if one ore more of these three fields is 0, it will not be used in calculating the maximum heating design flow rate).

#### Field: Design Specification Zone Air Distribution Object Name[LINK]

The name of the DesignSpecification:ZoneAirDistribution object, defining the air distribution effectiveness and secondary recirculation air fraction, that applies to the zone or zone list. This object may be used for the same zone in the Controller:MechanicalVentilation object if no such DesignSpecification:ZoneAirDistribution object is specified.

An IDF example:

Sizing:Zone,
SPACE5-1,                !- Name of a zone
14.,                     !- Zone cooling design supply air temperature {C}
50.,                     !- Zone heating design supply air temperature {C}
0.009,                   !- Zone cooling design supply air humidity ratio {kg-H2O/kg-air}
0.004,                   !- Zone heating design supply air humidity ratio {kg-H2O/kg-air}
DSOA1,                   !- Design Specification Outdoor Air Object Name
0.0,                     !- zone heating sizing factor
0.0,                     !- zone cooling sizing factor
designdaywithlimit,      !- Cooling Design Air Flow Method
,                        !- cooling design air flow rate {m3/s}
,                        !- Cooling Minimum Air Flow per zone area {m3/s-m2}
,                        !- Cooling Minimum Air Flow {m3/s}
,                        !- fraction of the cooling design air flow rate
designday,               !- Heating Design Air Flow Method
,                        !- heating design air flow rate {m3/s}
,                        !- heating max air flow per zone area {m3/s-m2}
,                        !- heating max air flow {m3/s}
,                        !- fraction of the cooling design air flow rate
DSZADO1;                 !- Design Specification Zone Air Distribution Object Name

DesignSpecification:OutdoorAir,
DSOA1,                   !- Name
SUM,                     !- Outdoor Air Method
0.00236,                 !- Outdoor Air Flow per Person
0.000305,                !- Outdoor Air Flow per Zone Floor Area
0.0,                     !- Outdoor Air Flow per Zone
0.0,                     !- Outdoor Air Flow Air Changes per Hour
;                        !- Outdoor Air Flow Rate Fraction Schedule Name

DesignSpecification:ZoneAirDistribution,
1.0,                     !- Zone Air Distribution Effectiveness in Cooling Mode
1.0,                     !- Zone Air Distribution Effectiveness in Heating Mode
,                        !- Zone Air Distribution Effectiveness Schedule Name
0.3;                     !- Zone Secondary Recirculation Fraction

The zone design air flow rates and loads are output onto the local file “epluszsz.” where is the extension from the sizing style object (default is csv - a comma separated file epluszsz.csv). The columns are clearly labeled. It will easily import into Excel or other spreadsheet program that accepts delimited files. All of these values are design air flow rates and loads calculated by the program. No sizing factors have been applied.

The calculated zone design air flow rates and the user input or altered zone design air flow rates are also reported on the eplusout.eio file. The values are printed out for each zone as comma separated records beginning with Zone Sizing. Items output on the eio file are: zone name, load type (heating or cooling), design load, calculated design air flow rate, user design air flow rate, design day name, time of peak, outside temperature at peak, outside humidity ratio at peak.

The Sizing:System object contains the input needed to perform a central forced air system design air flow, heating capacity, and cooling capacity calculation for a system serving one or more zones. The information needed consists of the outside environmental conditions and the design supply air temperatures, outdoor air flow rate, and minimum system air flow ratio.

The outside conditions come from the design days in the input. A system sizing calculation is performed for every design day in the input file and the resulting maximum heating and cooling air flow rates and capacities are saved for use in the component sizing calculations.

Supply air conditions are specified by inputting a supply air temperature for cooling, a supply air temperature for heating, and a preheat temperature.

The system sizing calculation sums the zone design air flow rates to obtain a system supply air flow rate. The design conditions and the outdoor air flow rate are used to calculate a design mixed air temperature. The temperature plus the design supply air temperatures allows the calculation of system design heating and cooling capacities.

The name of the AirLoopHVAC corresponding to this Sizing:System object. This is the air system for which the design calculation will be made using the input data of this Sizing:System Object.

The user specified type of load on which to size the central system. The choices are Sensible, Total and VentilationRequirement. Sensible means that the central system supply air flow rate will be determined by combining the zone design air flow rates, which have been calculated to meet the zone sensible loads from the design days. VentilationRequirement means that the central system supply air flow rate will be determined by the system ventilation requirement. In addition Sensible tells the program to size the central cooling coil using entering air flow rate and air conditions at the sensible load peak; Total indicates that the program should size the central cooling coil at the air flow rate and conditions at the total load peak. The central heating coil is always sized at the conditions at the peak sensible heating load.

#### Field: Design Outdoor Air Flow Rate[LINK]

The design outdoor air flow rate in cubic meters per second. Generally this should be the minimum outdoor air flow. It is used for both heating and cooling design calculations. The assumption for cooling is that any outdoor air economizer will be closed. If Autosize is input the outdoor air flow rate will be taken from the sum of the zone outdoor air flow rates or calculated based on the System Outdoor Air Method selection (field below).

#### Field: Central Heating Maximum System Air Flow Ratio[LINK]

The ratio of the maximum system air flow rate for heating to the maximum system air flow rate. The value must be between 0 and 1. For constant volume systems the ratio should be set to 1. This ratio should be set to reflect what the user expects the system flow rate to be when maximum heating demand occurs. This ratio is used in calculating the central system heating capacity. Thus if the system is VAV with the zone VAV dampers held at minimum flow when there is a zone heating demand, this ratio should be set to the minimum flow ratio. If the zone VAV dampers are reverse action and can open to full flow to meet heating demand, this ratio should be set to 1. The default is set to 0.5, reflecting the fact that VAV dampers are typically not allowed to fully open during heating.

The design air temperature exiting the preheat coil (if any) in degrees Celsius.

#### Field: Preheat Design Humidity Ratio[LINK]

The design humidity ratio exiting the preheat coil (if any) in kilograms of water per kilogram of dry air. (kgWater/kgDryAir)

The design air temperature exiting the precooling coil (if any) in degrees Celsius.

#### Field: Precool Design Humidity Ratio[LINK]

The design humidity ratio exiting the precooling coil (if any) in kilograms of water per kilogram of dry air. (kgWater/kgDryAir)

#### Field: Central Cooling Design Supply Air Temperature[LINK]

The design supply air temperature for cooling in degrees Celsius. This should be the temperature of the air exiting the central cooling coil.

#### Field: Central Heating Design Supply Air Temperature[LINK]

The design supply air temperature for heating in degrees Celsius. This can be either the reset temperature for a single duct system or the actual hot duct supply air temperature for dual duct systems. It should be the temperature at the exit of the main heating coil.

#### Field: Type of Zone Sum to Use[LINK]

If the input is coincident the central system air flow rate will be sized on the sum of the coincident zone air flow rates. If the input is noncoincident the central system air flow rate will be sized on the sum of the noncoincident zone air flow rates. The default is noncoincident.

#### Field: 100% Outdoor Air in Cooling[LINK]

Entering Yes means the system will be sized for cooling using 100% outdoor air. Entering No means the system will be sized for cooling using minimum outside air (the default).

#### Field: 100% Outdoor Air in Heating[LINK]

Entering Yes means the system will be sized for heating using 100% outdoor air. Entering No means the system will be sized for heating using minimum outside air (the default).

#### Field: Central Cooling Design Supply Air Humidity Ratio[LINK]

The design humidity ratio in kilograms of water per kilogram of dry air at the exit of the central cooling coil. (kgWater/kgDryAir) The default is .008.

#### Field: Central Heating Design Supply Air Humidity Ratio[LINK]

The design humidity ratio in kilograms of water per kilogram of dry air at the exit of the central heating coil. (kgWater/kgDryAir) The default is .008.

#### Field: Cooling Supply Air Flow Rate Method[LINK]

The input of this field must be the method used to determine the airloop cooling supply air volume flow rate. The input must be either, DesignDay, Flow/System, FlowPerFloorArea, FractionOfAutosizedCoolingAirflow, or FlowPerCoolingCapacity. DesignDay means the program will calculate the system design cooling supply air volume flow rate using the System Sizing input data and a design day simulation. Flow/System means that the program will use the input of the field Cooling Design Air Flow Rate as the system design cooling supply air volume flow rate. FlowPerFloorArea means the program calculates the cooling supply air volume flow rate from zone floor area served by the airloop and user specified Flow Per Floor Area value. FractionOfAutosizedCoolingAirflow means the program calculates the cooling supply air volume flow rate from user specified fraction and the autosized design cooling supply air volume flow rate value determined by the simulation. FlowPerCoolingCapacity means the supply air volume is calculated from user specified flow per cooling capacity and design cooling capacity determined by the simulation. The default method is DesignDay: i.e., the program uses the calculated design values.

#### Field: Cooling Supply Air Flow Rate[LINK]

The design system cooling air flow rate in cubic meters per second. This input is an alternative to using the program autocalculated value. This input is used if Coolingi Supply Air Flow Rate Method is Flow/System. This value will not be multiplied by any sizing factor or by zone multipliers. If using zone multipliers, this value must be large enough to serve the multiplied zones.

#### Field: Cooling Supply Air Flow Rate Per Floor Area {m3/s-m2}[LINK]

Enter the cooling supply air volume flow rate per zone conditioned floor area in m3/s-m2. This field is required field when the Cooling Supply Air Flow Rate Method is FlowPerFloorArea. This field may be left blank if a cooling coil is not included in the airloop or the Cooling Supply Air Flow Rate Method is not FlowPerFloorArea. The program calculates the cooling supply air volume flow rate from the cooled floor area served by the air loop and the Flow Per Unit Area value specified by the user.

#### Field: Cooling Fraction of Autosized Cooling Design Supply Air Flow Rate[LINK]

Enter the cooling supply air volume flow rate as a fraction of the airloop autosized cooling supply air flow rate. This input field is required when the Cooling Supply Air Flow Rate Method is FractionOfAutosizedCoolingAirflow. This input field may be left blank if a cooling coil is not included in the airloop or the Cooling Supply Air Flow Rate Method is not FractionOfAutosizedCoolingAirflow. The program calculates the cooling supply air volume flow rate from the design autosized cooling supply air flow rate and user specified fraction.

#### Field: Cooling Supply Air Flow Rate Per Unit Cooling Capacity {m3/s-W}[LINK]

Enter the cooling supply air volume flow rate per unit cooling capacity in m3/s-W. This input field is required when the Cooling Supply Air Flow Rate Method is FlowPerCoolingCapacity. This field may be left blank if a cooling coil is not included in the airloop or the Cooling Supply Air Flow Rate Method is not FlowPerCoolingCapacity. The program calculates the airloop cooling supply air volume flow rate from the design autosized cooling capacity and user specified Flow Per Cooling Capacity value.

#### Field: Heating Supply Air Flow Rate Method[LINK]

The input of this field must be the method used to determine the airloop heating supply air volume flow rate. The input must be either, DesignDay, Flow/System, FlowPerFloorArea, FractionOfAutosizedHeatingAirflow, FractionOfAutosizedCoolingAirflow or FlowPerHeatingCapacity. DesignDay means the program will calculate the system design heating supply air volume flow rate using the System Sizing input data and a design day simulation. Flow/System means that the program will use the input of the field Heating Design Air Flow Rate as the system design heating supply air volume flow rate. FlowPerFloorArea means the program calculates the system heating supply air volume flow rate from zone floor area served by the airloop and user specified Flow Per Floor Area value. FractionOfAutosizedHeatingAirflow means the program calculates the system heating supply air volume flow rate from user specified fraction and the autosized system design heating supply air volume flow rate value determined by the simulation. FractionOfAutosizedCoolingAirflow means the program calculates the system heating supply air volume flow rate from user specified fraction and the autosized system design cooling supply air volume flow rate value determined by the simulation. FlowPerHeatingCapacity means the system heating supply air volume is calculated from user specified flow per heating capacity and design heating capacity determined by the simulation. The default method is DesignDay: i.e., the program uses the calculated design values.

#### Field: Heating Supply Air Flow Rate[LINK]

The design system heating air flow rate in cubic meters per second. This input is an alternative to using the program autocalculated value. This input is used if Heating Supply Air Flow Rate Method is Flow/System. This value will not be multiplied by any sizing factor or by zone multipliers. If using zone multipliers, this value must be large enough to serve the multiplied zones.

#### Field: Heating Supply Air Flow Rate Per Floor Area {m3/s-m2}[LINK]

Enter the heating supply air volume flow rate per zone conditioned floor area in m3/s-m2. This field is required field when the Heating Supply Air Flow Rate Method is FlowPerFloorArea. This field may be left blank if a heating coil is not included in the airloop or the Heating Supply Air Flow Rate Method is not FlowPerFloorArea. The program calculates the heating supply air volume flow rate from the heated or cooled floor area served by the air loop and the Flow Per Unit Area value specified by the user.

#### Field: Heating Fraction of Autosized Heating Supply Air Flow Rate[LINK]

Enter the heating supply air volume flow rate as a fraction of the airloop autosized heating supply air flow rate. This input field is required when the Heating Supply Air Flow Rate Method is FractionOfAutosizedHeatingAirflow. This input field may be left blank if heating coil is not included in the airloop or the Heating Supply Air Flow Rate Method is not FractionOfAutosizedHeatingAirflow. The program calculates the heating supply air volume flow rate from the design autosized heating supply air flow rate and user specified fraction.

#### Field: Heating Fraction of Autosized Cooling Supply Air Flow Rate[LINK]

Enter the heating supply air volume flow rate as a fraction of the airloop autosized cooling supply air flow rate. This input field is required when the Heating Supply Air Flow Rate Method is FractionOfAutosizedCoolingAirflow. This input field may be left blank if heating coil is not included in the airloop or the Heating Supply Air Flow Rate Method is not FractionOfAutosizedCoolingAirflow. The program calculates the heating supply air volume flow rate from the design autosized cooling supply air flow rate and user specified fraction.

#### Field: Heating Design Supply Air Flow Rate Per Unit Heating Capacity {m3/s-W}[LINK]

Enter the heating supply air volume flow rate per unit heating capacity in m3/s-W. This input field is required when the Heating Design air Flow Method is FlowPerCoolingCapacity. This field may be left blank if a heating coil is not included in the airloop or the Heating Design air Flow Method is not FlowPerHeatingCapacity. The program calculates the airloop heating supply air volume flow rate from the design autosized heating capacity and user specified Flow Per Heating Capacity value.

#### Field: System Outdoor Air Method[LINK]

The method used to calculate the system minimum outdoor air flow. The two choices are ZoneSum and VentilationRateProcedure (VRP). ZoneSum sums the outdoor air flows across all zones served by the system. VRP uses the multi-zone equations defined in 62.1-2007 to calculate the system outdoor air flow. VRP considers zone air distribution effectiveness and zone diversification of outdoor air fractions.

#### Field: Zone Maximum Outdoor Air Fraction[LINK]

This positive numeric input is the zone maximum outdoor air fraction. For an air loop, when a zone requires outdoor air higher than the user specified Zone Maximum Outdoor Air Fraction, the zone supply air flow will be increased to cap the outdoor air fraction at the maximum value. This allows the system level outdoor air flow to be reduced while the total supply air flow increases. Valid values are from 0 to 1.0. Default is 1.0 which indicates zones can have 100% outdoor air maintaining backward compatibility. This inputs work for constant volume air systems, single and dual duct VAV systems.

#### Field Cooling Design Capacity Method[LINK]

Enter the method used to determine the cooling design capacity for scalable sizing. Input allowed is either None, CoolingDesignCapacity, CapacityPerFloorArea, and FractionOfAutosizedCoolingCapacity. None is used when a cooling coil is not included in the airloop. If this input field is left blank, or None is specified, then the autosized design cooling capacity determined by the program is used. CoolingDesignCapacity means user specifies the magnitude of cooling capacity or the program calculates the design cooling capacity if autosize is specified. CapacityPerFloorArea means the program calculates the design cooling capacity from user specified cooling capacity per floor area and floor area of the zones served by the airloop. FractionOfAutosizedCoolingCapacity means the program calculates the design cooling capacity from user specified fraction and the auto-sized design cooling capacity. If the value this input field is blank or specified as None, then the next three input fields are not required. The default method is CoolingDesignCapacity.

#### Field: Cooling Design Capacity {W}[LINK]

Enter the magnitude of the cooling capacity in Watts. This input is an alternative to using the program auto-calculated cooling capacity value. This input is a required field when the Cooling Design Capacity Method is CoolingDesignCapacity. This field may be left blank if a cooling coil is not included in the air loop or alternative method is specified. This input field is autosizable.

#### Field: Cooling Design Capacity Per Floor Area {W/m2}[LINK]

Enter the cooling capacity per unit floor area in m3/s-m2. This field is required field when the Cooling Design Capacity Method is CapacityPerFloorArea. This field may be left blank if a cooling coil is not included in the airloop or the Cooling Design Capacity Method is not CapacityPerFloorArea. The program calculates the cooling capacity from floor area of the zones served by the airloop and the cooling capacity per unit floor area value specified by the user.

#### Field: Fraction of Autosized Cooling Design Capacity[LINK]

Enter the cooling capacity as a fraction of the autosized cooling capacity. This input field is required when the Cooling Design Capacity Method is FractionOfAutosizedCoolingCapacity. This input field may be left blank if a cooling coil is not included in the zone HVAC equipment or the Cooling Design Capacity Method is not FractionOfAutosizedCoolingCapacity. The program calculates the cooling capacity from the design autosized cooling capacity and user specified fraction. Design day sizing run must be specified.

#### Field: Heating Design Capacity Method[LINK]

Enter the method used to determine the heating design capacity for scalable sizing. Input allowed is either None, HeatingDesignCapacity, CapacityPerFloorArea, and FractionOfAutosizedHeatingCapacity. None is used when a heating coil is not included in the airloop. If this input field is left blank, then the autosized design heating capacity determined by the program is used. HeatingDesignCapacity means user specifies the magnitude of heating capacity or the program calculates the design heating capacity if autosize is specified. CapacityPerFloorArea means the program calculates the design heating capacity from user specified heating capacity per floor area and floor area of the zones served by the airllop. FractionOfAutosizedHeatingCapacity means the program calculates the design heating capacity from user specified fraction and the auto-sized design heating capacity. If the value this input field is blank or specified as None, then the next three input fields are not required. The default method is HeatingDesignCapacity.

#### Field: Heating Design Capacity {W}[LINK]

Enter the magnitude of the heating capacity in Watts. This input is an alternative to using the program auto-calculated heating capacity value. This input is a required field when the Heating Design Capacity Method is HeatingDesignCapacity. This field may be left blank if a heating coil is not included in the airloop or alternative method is specified. This input field is autosizable.

#### Field: Heating Design Capacity Per Floor Area {W/m2}[LINK]

Enter the heating capacity per unit floor area in m3/s-m2. This field is required field when the Heating Design Capacity Method is CapacityPerFloorArea. This field may be left blank if a heating coil is not included in the airloop or the Heating Design Capacity Method is not CapacityPerFloorArea. The program calculates the heating capacity from floor area of the zones served by the airloop and the heating capacity per unit floor area value specified by the user.

#### Field: Fraction of Autosized Heating Design Capacity[LINK]

Enter the heating capacity as a fraction of the autosized heating capacity. This input field is required when the Heating Design Capacity Method is FractionOfAutosizedHeatingCapacity. This input field may be left blank if heating coil is not included in the airloop or the Heating Design Capacity Method is not FractionOfAutosizedHeatingCapacity. The program calculates the heating capacity from the design autosized cooling capacity and user specified fraction.

#### Field: Central Cooling Capacity Control Method[LINK]

Specifies how the central cooling coil will be controlled, which affects the coil sizing calculation. There are 4 choices: VAV, Bypass, VT, and OnOff. Choose VAV if the cooling output is controlled by varying the air flow. Bypass should be chosen if the capacity is controlled by bypassing a variable fraction of the mixed air around the coil face. VT indicates that cooling coil output is controlled by varying the coil exit temperature while the flow rate is constant. And OnOff means that the cooling output is controlled by cycling the air flow.

An IDF example:

Sizing:System,
VAV Sys 1,               !- AirLoop Name
sensible,                !- Type of Load to Size On
autosize,                !- Design Outdoor Air Flow Rate {m3/s}
0.3,                     !- Minimum System Air Flow Ratio
4.5,                     !- Preheat Design Temperature {C}
.008,                    !- Preheat Design Humidity Ratio {kgWater/kgDryAir}
11.0,                    !- Precool Design Temperature {C}
.008,                    !- Precool Design Humidity Ratio {kgWater/kgDryAir}
12.8,                    !- Central Cooling Design Supply Air Temperature {C}
16.7,                    !- Central Heating Design Supply Air Temperature {C}
noncoincident,           !- Sizing Option
no,                      !- 100% Outdoor Air in Cooling
no,                      !- 100% Outdoor Air in Heating
0.008,                   !- Central Cooling Design Supply Air Humidity Ratio {kgWater/kgDryAir}
0.008,                   !- Central Heating Design Supply Air Humidity Ratio {kgWater/kgDryAir}
designday,               !- Cooling Supply Air Flow Rate Method
0,                       !- Cooling Supply Air Flow Rate {m3/s}
,                        !- Cooling Supply Air Flow Rate Per Floor Area {m3/s-m2}
,                        !- Cooling Fraction of Autosized Cooling Supply Air Flow Rate {-}
,                        !- Cooling Supply Air Flow Rate Per Unit Cooling Capacity {m3/s-W}
designday,               !- Heating Supply Air Flow Rate Method
0,                       !- Heating Supply Air Flow Rate {m3/s}
,                        !- Heating Supply Air Flow Rate Per Floor Area {m3/s-m2}
,                        !- Heating Fraction of Autosized Heating Supply Air Flow Rate {-}
,                        !- Heating Fraction of Autosized Cooling Supply Air Flow Rate {-}
,                        !- Heating Supply Air Flow Rate Per Unit Heating Capacity {m3/s-W}
ZoneSum,                 !- System Outdoor Air Method
0.5,                     !- Zone Maximum Outdoor Air Fraction
CoolingDesignCapacity,   !- Cooling Design Capacity Method
autosize,                !- Cooling Design Capacity {W}
,                        !- Cooling Design Capacity Per Floor Area {W/m2}
,                        !- Fraction of Autosized Cooling Design Capacity {-}
HeatingDesignCapacity,   !- Heating Design Capacity Method
autosize,                !- Heating Design Capacity {W}
,                        !- Heating Design Capacity Per Floor Area {W/m2}
;                        !- Fraction of Autosized Cooling Design Capacity {-}

The system design air flow rates and heating and cooling capacities are output onto the local file “eplusssz.<ext>” where <ext> is the extension from the sizing style object (default is csv – a comma separated file eplusssz.csv). The columns are clearly labeled. It will easily import into Excel or other spreadsheet program that accepts delimited files. The results are calculated values and do not include any user input system flow rates.

The calculated system design air flow rates and the user input system design air flow rates are also reported on the eplusout.eio file. The values are printed out for each system as comma separated records beginning with System Sizing. An example is:

! <System Sizing Information>c++, System Name, Field Description, Value
System Sizing, VAV SYS 1, Calculated Cooling Design Air Flow Rate [m3/s],   1.3194
System Sizing, VAV SYS 1, User Cooling Design Air Flow Rate [m3/s],   1.5000
System Sizing, VAV SYS 1, Calculated Heating Design Air Flow Rate [m3/s],  0.90363
System Sizing, VAV SYS 1, User Heating Design Air Flow Rate [m3/s],   1.0000

The Sizing:Plant object contains the input needed for the program to calculate plant loop flow rates and equipment capacities when autosizing. This information is initially used by components that use water for heating or cooling such as hot or chilled water coils to calculate their maximum water flow rates. These flow rates are then summed for use in calculating the Plant Loop flow rates.

The program will size any number of chilled water, hot water, condenser water and other plant loops. There should be one Sizing:Plant object for each plant loop that is to be autosized.

#### Field: Plant or Condenser Loop Name[LINK]

The name of a Plant Loop or Condenser Loop object corresponding to this Sizing:Plant object. This is the plant loop for which this data will be used for calculating the loop flow rate.

The possible inputs are Heating, Steam, Cooling, or Condenser.

#### Field: Design Loop Exit Temperature[LINK]

The water temperature in degrees Celsius at the exit of the supply side of the plant loop, Thus this is the temperature of the water supplied to the inlet of chilled or hot water coils and other equipment that places loads on a plant loop.

#### Field: Loop Design Temperature Difference[LINK]

The design temperature rise (for cooling or condenser loops) or fall (for heating loops) in degrees Celsius across the demand side of a plant loop. This temperature difference is used by component models to determine flow rates required to meet design capacities. Larger values lead to smaller design flow rates.

This field is optional. This field controls how concurrence issues impact the plant loop design flow rate. If it is not used then the program uses noncoincident method, which is the historical behavior prior to version 8.3. There are two choices, noncoincident and coincident. The use of Coincident sizing option requires that the SimulationControl object be set to YES for the input field called Do HVAC Sizing Simulation for Sizing Periods.

#### Field: Zone Timesteps in Averaging Window[LINK]

This field is optional and is only used if the preceding field is set to Coincident. This is the number of zone timesteps used in a moving average to determine the design flow rate from HVAC Sizing Simulation approach. This allows using a broader average over time when using coincident plant sizing. This is similar in concept to the similar field in Sizing:Parameters which specifies the averaging window for zone loads. The default is 1.

#### Field: Coincident Sizing Factor Mode[LINK]

This field is only used if the sizing option is set to Coincident. This field controls the behavior of coincident sizing with respect to what, if any, sizing factor should be applied to further modify the flow rate measured while running HVAC Sizing Simulations. There are four options. Enter the keyword None to use the raw value for flow rate without modification. Enter the keyword GlobalHeatingSizingFactor to modify the flow by the sizing factor entered in the object called Sizing:Parameters for heating. Enter the keyword GlobalCoolingSizingFactor to modify the flow by the sizing factor entered in the object called Sizing:Parameters for cooling. Enter the keyword LoopComponentSizingFactor to modify the flow by a sizing factor determined from the combination of component-level sizing factors in the associated plant loop.

An IDF example:

Sizing:Plant,
Chilled Water Loop, ! name of loop
Cooling,            ! type of loop
7.22,               ! chilled water supply temperature
6.67,               ! chilled water delta T
NonCoincident,      !- Sizing Option
1,                  !- Zone Timesteps in Averaging Window
GlobalCoolingSizingFactor; !- Coincident Sizing Factor Mode