EnergyPlus9.2 OA Control for PTHP System

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Hi I'm trying to simulate a conditioned zone using ZoneHVAC:PackagedTerminalHeatPump with outdoor air fed into its OA mixer. I'd like to apply control to the OA rates based on the design occupancy, so I set up a Controller:OutdoorAir object, linked with Controller:MechanicalVentilation object (set with Demand Control Ventilation to "Yes").

In my mind this should allow for the OA rate to ramp down when there is less than 100% design occupancy in the zone. However, Looking into the Zone Mechanical Ventilation Standard Density Volume Flow Rate output variable, it appears the system always allows for design OA flow rate (i.e. maximum for 100% occupancy), during all occupied hour. No variation at all.

I am quite new to working with Open Studio & Energy Plus. Would appreciate your thoughts & help on the above.

Cheers!

!- =========== ALL OBJECTS IN CLASS: CONTROLLER:OUTDOORAIR ===========

Controller:OutdoorAir,

OAController-Court,      !- Name
PTHP-Court Relief Air Node,  !- Relief Air Outlet Node Name
Node 8,                  !- Return Air Node Name
PTHP-Court Mixed Air Node,  !- Mixed Air Node Name
PTHP-Court OA Node,      !- Actuator Node Name
autosize,                !- Minimum Outdoor Air Flow Rate {m3/s}
autosize,                !- Maximum Outdoor Air Flow Rate {m3/s}
NoEconomizer,            !- Economizer Control Type
ModulateFlow,            !- Economizer Control Action Type
,                        !- Economizer Maximum Limit Dry-Bulb Temperature {C}
,                        !- Economizer Maximum Limit Enthalpy {J/kg}
,                        !- Economizer Maximum Limit Dewpoint Temperature {C}
,                        !- Electronic Enthalpy Limit Curve Name
,                        !- Economizer Minimum Limit Dry-Bulb Temperature {C}
NoLockout,               !- Lockout Type
ProportionalMinimum,     !- Minimum Limit Type
,                        !- Minimum Outdoor Air Schedule Name
,                        !- Minimum Fraction of Outdoor Air Schedule Name
,                        !- Maximum Fraction of Outdoor Air Schedule Name
MechVentControl,         !- Mechanical Ventilation Controller Name
,                        !- Time of Day Economizer Control Schedule Name
No,                      !- High Humidity Control
,                        !- Humidistat Control Zone Name
1,                       !- High Humidity Outdoor Air Flow Ratio
Yes,                     !- Control High Indoor Humidity Based on Outdoor Humidity Ratio
BypassWhenWithinEconomizerLimits;  !- Heat Recovery Bypass Control Type

!- =========== ALL OBJECTS IN CLASS: CONTROLLER:MECHANICALVENTILATION ===========

Controller:MechanicalVentilation,

MechVentControl,         !- Name
BCA CL9b School AC,      !- Availability Schedule Name
Yes,                     !- Demand Controlled Ventilation
ProportionalControlBasedOnDesignOccupancy,  !- System Outdoor Air Method
1,                       !- Zone Maximum Outdoor Air Fraction {dimensionless}
Z-Court,                 !- Zone 1 Name
AS1668.2 10Ls/p,         !- Design Specification Outdoor Air Object Name 1
Z-Court Design Spec Zone Air Dist;  !- Design Specification Zone Air Distribution Object Name 1

!- =========== ALL OBJECTS IN CLASS: OUTDOORAIR:MIXER ===========

OutdoorAir:Mixer,

PTHP-Court OA Mixer,     !- Name
PTHP-Court Mixed Air Node,  !- Mixed Air Node Name
PTHP-Court OA Node,      !- Outdoor Air Stream Node Name
PTHP-Court Relief Air Node,  !- Relief Air Stream Node Name
Node 8;                  !- Return Air Stream Node Name

!- =========== ALL OBJECTS IN CLASS: NODELIST ===========

NodeList,

Z-Court Inlet Node List, !- Name
Node 9;                  !- Node 1 Name

NodeList,

Z-Court Exhaust Node List,  !- Name
Node 8;                  !- Node 1 Name

!- =========== ALL OBJECTS IN CLASS: OUTDOORAIR:NODE ===========

OutdoorAir:Node,

Model Outdoor Air Node;  !- Name

!- =========== ALL OBJECTS IN CLASS: OUTDOORAIR:NODELIST ===========

OutdoorAir:NodeList,

PTHP-Court OA Node;      !- Node or NodeList Name 1