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You can force the simulation to average sizing results by using the Sizing:Parameters object. In the PNNL medium office model the averaging window is 2 hours. At times when the Tstat temperature is setup, the zone airflow will spike to meet the increased load. Since real systems cannot meet this load immediately, you do not want the simulated system to be sized to meet that load. A workaround to this method is to use constant temperature setpoints during the design days so zone airflow calculations only include the loads and not the change in Tstat set point temperature. If you would like to test this theory, change the Timesteps in Averaging Window to 1 and reevaluate the component sizes.

Timestep,4;

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

!    HTGSETP_SCH_PACU_VAV_bot,             
Schedule:Compact,
 HTGSETP_SCH_PACU_VAV_bot,!- Name
 Temperature,             !- Schedule Type Limits Name
 Through: 12/31,          !- Field 1
 For: WinterDesignDay,    !- Field 2
 Until: 05:00,15.6,       !- Field 3
 Until: 06:00,17.6,       !- Field 5
 Until: 07:00,19.6,       !- Field 7
 Until: 22:00,21.0,       !- Field 9
 Until: 24:00,15.6,       !- Field 11
 For SummerDesignDay,     !- Field 24
 Until: 24:00,15.6,       !- Field 25

!    CLGSETP_SCH_NO_SETBACK,             
  Schedule:Compact,
  CLGSETP_SCH_NO_SETBACK,  !- Name
  Temperature,             !- Schedule Type Limits Name
  Through: 12/31,          !- Field 1
  For: SummerDesignDay,    !- Field 2
  Until: 05:00,26.7,       !- Field 3
  Until: 06:00,25.7,       !- Field 5
  Until: 07:00,25.0,       !- Field 7
  Until: 22:00,24.0,       !- Field 9
  Until: 24:00,26.7,       !- Field 11
  For WinterDesignDay,     !- Field 35
  Until: 24:00,24.0,       !- Field 36