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Autosizing requires input for operating conditions. Sizing:Zone objects are required and Sizing:System objects will be required to size air loop equipment. The best way to tell which example files have a specific object is to look at the ExampleFiles-ObjectsLink.html file.

To autosize your model, turn on the appropriate Do * Sizing Calculation input by entering Yes. Each of these fields will also require a Sizing:Zone, Sizing:System, or Sizing:Plant object, respectively. Look at the InputOutputReference document for a description of these objects.

SimulationControl,
  Yes,                     !- Do Zone Sizing Calculation
  Yes,                     !- Do System Sizing Calculation
  Yes,                     !- Do Plant Sizing Calculation
  Yes,                     !- Run Simulation for Sizing Periods
  Yes;                     !- Run Simulation for Weather File Run Periods

Then add the appropriate sizing object. For example, for zone sizing, use a Sizing:Zone object:

Sizing:Zone,
  SPACE1-1,                !- Zone or ZoneList Name
  SupplyAirTemperature,    !- Zone Cooling Design Supply Air Temperature Input Method
  14.,                     !- Zone Cooling Design Supply Air Temperature {C}
  ,                        !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
  SupplyAirTemperature,    !- Zone Heating Design Supply Air Temperature Input Method
  50.,                     !- Zone Heating Design Supply Air Temperature {C}
  ,                        !- Zone Heating Design Supply Air Temperature Difference {deltaC}
  0.009,                   !- Zone Cooling Design Supply Air Humidity Ratio {kgWater/kgDryAir}
  0.004,                   !- Zone Heating Design Supply Air Humidity Ratio {kgWater/kgDryAir}
  SZ DSOA SPACE1-1,        !- 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 Floor Area {m3/s-m2}
  ,                        !- Cooling Minimum Air Flow {m3/s}
  ,                        !- Cooling Minimum Air Flow Fraction
  DesignDay,               !- Heating Design Air Flow Method
  ,                        !- Heating Design Air Flow Rate {m3/s}
  ,                        !- Heating Maximum Air Flow per Zone Floor Area {m3/s-m2}
  ,                        !- Heating Maximum Air Flow {m3/s}
  ;                        !- Heating Maximum Air Flow Fraction

The DesignSpecification:OutdoorAir object is used to specify how much outdoor air and by what method you will supply to each zone. You can also adjust the sizing factor for cooling and/or heating if needed.

DesignSpecification:OutdoorAir,
  SZ DSOA SPACE1-1,        !- Name
  sum,                     !- Outdoor Air Method
  0.00236,                 !- Outdoor Air Flow per Person {m3/s-person}
  0.000305,                !- Outdoor Air Flow per Zone Floor Area {m3/s-m2}
  0.0;                     !- Outdoor Air Flow per Zone {m3/s}

Sizing:Parameters,
  1.0,                     !- Heating Sizing Factor
  1.0,                     !- Cooling Sizing Factor
  ;                        !- Timesteps in Averaging Window

Autosizing requires input for operating conditions. Sizing:Zone objects are required and Sizing:System objects will be required to size air loop equipment. The best way to tell which example files have a specific object is to look at the ExampleFiles-ObjectsLink.html file.

To autosize your model, turn on the appropriate Do * Sizing Calculation input by entering Yes. Each of these fields will also require a Sizing:Zone, Sizing:System, or Sizing:Plant object, respectively. If you are using ZoneHVAC equipment (baseboard, PTAC, etc.) you will need to add the Sizing:Zone object. If you are using AirloopHVAC you will need both the Sizing:Zone and Sizing:System objects. If you have a plant loop, all three sizing objects are needed. Look at the InputOutputReference document for a description of these objects.

SimulationControl,
  Yes,                     !- Do Zone Sizing Calculation
  Yes,                     !- Do System Sizing Calculation
  Yes,                     !- Do Plant Sizing Calculation
  Yes,                     !- Run Simulation for Sizing Periods
  Yes;                     !- Run Simulation for Weather File Run Periods

Then add the appropriate sizing object. For example, for zone sizing, use a Sizing:Zone object:

Sizing:Zone,
  SPACE1-1,                !- Zone or ZoneList Name
  SupplyAirTemperature,    !- Zone Cooling Design Supply Air Temperature Input Method
  14.,                     !- Zone Cooling Design Supply Air Temperature {C}
  ,                        !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
  SupplyAirTemperature,    !- Zone Heating Design Supply Air Temperature Input Method
  50.,                     !- Zone Heating Design Supply Air Temperature {C}
  ,                        !- Zone Heating Design Supply Air Temperature Difference {deltaC}
  0.009,                   !- Zone Cooling Design Supply Air Humidity Ratio {kgWater/kgDryAir}
  0.004,                   !- Zone Heating Design Supply Air Humidity Ratio {kgWater/kgDryAir}
  SZ DSOA SPACE1-1,        !- 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 Floor Area {m3/s-m2}
  ,                        !- Cooling Minimum Air Flow {m3/s}
  ,                        !- Cooling Minimum Air Flow Fraction
  DesignDay,               !- Heating Design Air Flow Method
  ,                        !- Heating Design Air Flow Rate {m3/s}
  ,                        !- Heating Maximum Air Flow per Zone Floor Area {m3/s-m2}
  ,                        !- Heating Maximum Air Flow {m3/s}
  ;                        !- Heating Maximum Air Flow Fraction

The DesignSpecification:OutdoorAir object is used to specify how much outdoor air and by what method you will supply to each zone. You can also adjust the sizing factor for cooling and/or heating if needed.

DesignSpecification:OutdoorAir,
  SZ DSOA SPACE1-1,        !- Name
  sum,                     !- Outdoor Air Method
  0.00236,                 !- Outdoor Air Flow per Person {m3/s-person}
  0.000305,                !- Outdoor Air Flow per Zone Floor Area {m3/s-m2}
  0.0;                     !- Outdoor Air Flow per Zone {m3/s}

Sizing:Parameters,
  1.0,                     !- Heating Sizing Factor
  1.0,                     !- Cooling Sizing Factor
  ;                        !- Timesteps in Averaging Window