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[EnergyPlus_Support] Re: AFN - Nat Vent Too much during cold / warm days
Hi Jean,
You can modulate the opening factor using any variable by writing your own EMS control code. I've done this before (modulating based on m3/s) and have pasted an example below if you want to copy it. I'll expect royalties.
However, high ACH shouldn't be a problem unless it affects occupant comfort in some way. Two ways it can do this are high air speeds (in excess of ~1m/s) or letting in too much cold air and cooling the space.
If you are letting in too much cold air, you might want to refine your zone dT modulation parameters. Yours look reasonable however, unless maybe your windows are large compared to your zone.
If your air speeds are too high [you can get a rough approximation of the jet speed at the window by dividing the volumetric flow rate (m3/s) by the opening area of the window (m2)] then you might consider adding an EMS controller like I've pasted below. This example modulates two windows separately.
Hope this helps.
Sam
!- =========== ALL OBJECTS IN CLASS: ENERGYMANAGEMENTSYSTEM:SENSOR ===========
EnergyManagementSystem:Sensor,
FlowIn288, !- Name
Win_288, !- Output:Variable or Output:Meter Index Key Name
AirflowNetwork Volume Flow Rate from Node 2 to 1; !- Output:Variable or Output:Meter Name
EnergyManagementSystem:Sensor,
FlowOut288, !- Name
Win_288, !- Output:Variable or Output:Meter Index Key Name
AirflowNetwork Volume Flow Rate from Node 1 to 2; !- Output:Variable or Output:Meter Name
EnergyManagementSystem:Sensor,
FlowIn289, !- Name
Win_289, !- Output:Variable or Output:Meter Index Key Name
AirflowNetwork Volume Flow Rate from Node 2 to 1; !- Output:Variable or Output:Meter Name
EnergyManagementSystem:Sensor,
FlowOut289, !- Name
Win_289, !- Output:Variable or Output:Meter Index Key Name
AirflowNetwork Volume Flow Rate from Node 1 to 2; !- Output:Variable or Output:Meter Name
!- =========== ALL OBJECTS IN CLASS: ENERGYMANAGEMENTSYSTEM:ACTUATOR ===========
EnergyManagementSystem:Actuator,
OpenFactor288, !- Name
Win_288, !- Actuated Component Unique Name
AirFlow Network Window/Door Opening, !- Actuated Component Type
Venting Opening Factor; !- Actuated Component Control Type
EnergyManagementSystem:Actuator,
OpenFactor289, !- Name
Win_289, !- Actuated Component Unique Name
AirFlow Network Window/Door Opening, !- Actuated Component Type
Venting Opening Factor; !- Actuated Component Control Type
!- =========== ALL OBJECTS IN CLASS: ENERGYMANAGEMENTSYSTEM:PROGRAMCALLINGMANAGER ===========
EnergyManagementSystem:ProgramCallingManager,
ProgramCallingManager1, !- Name
BeginTimestepBeforePredictor, !- EnergyPlus Model Calling Point
FlowRateLimitProgram; !- Program Name 1
!- =========== ALL OBJECTS IN CLASS: ENERGYMANAGEMENTSYSTEM:PROGRAM ===========
EnergyManagementSystem:Program,
FlowRateLimitProgram, !- Name
set FlowrateIn288=FlowIn288, !- Program Line 1
set FlowrateOut288=FlowOut288, !- Program Line 2
If (FlowrateIn288 > 15.0),!- A4
Set OpenFactor288 = 0,!- A5
ElseIf (FlowrateIn288 > 3.0),!- A4
Set OpenFactor288 = 0.7,!- A5
ElseIf (FlowrateIn288 > 2.5) && (FlowrateIn288<= 3.0), !- A6
Set OpenFactor288 = 0.75, !- A7
ElseIf (FlowrateIn288 > 2.0) && (FlowrateIn288<= 2.5), !- A8
Set OpenFactor288 = 0.8,!- A9
ElseIf (FlowrateOut288 > 3.0), !- A10
Set OpenFactor288 = 0.7,!- A11
ElseIf (FlowrateOut288 > 2.5) && (FlowrateOut288<= 3.0), !- A12
Set OpenFactor288 = 0.75, !- A13
ElseIf (FlowrateOut288 > 2.0) && (FlowrateOut288<= 2.5), !- A14
Set OpenFactor288 = 0.8,!- A15
Else,
Set OpenFactor288 = null,
Endif, !- A16
set FlowrateIn289=FlowIn289, !- A17
set FlowrateOut289=FlowOut289, !- A18
If (FlowrateIn289 > 15.0),!- A4
Set OpenFactor289 = 0,!- A5
ElseIf (FlowrateIn289 > 3.0),!- A19
Set OpenFactor289 = 0.7,!- A20
ElseIf (FlowrateIn289 > 2.5) && (FlowrateIn289<= 3.0), !- A21
Set OpenFactor289 = 0.75, !- A22
ElseIf (FlowrateIn289 > 2.0) && (FlowrateIn289<= 2.5), !- A23
Set OpenFactor289 = 0.8,!- A24
ElseIf (FlowrateOut289 > 3.0), !- A25
Set OpenFactor289 = 0.7,!- A26
ElseIf (FlowrateOut289 > 2.5) && (FlowrateOut289<= 3.0), !- A27
Set OpenFactor289 = 0.75, !- A28
ElseIf (FlowrateOut289 > 2.0) && (FlowrateOut289<= 2.5), !- A29
Set OpenFactor289 = 0.8,!- A30
Else,
Set OpenFactor288 = null,
EndIf; !- A31
!- =========== ALL OBJECTS IN CLASS: ENERGYMANAGEMENTSYSTEM:GLOBALVARIABLE ===========
EnergyManagementSystem:GlobalVariable,
FlowrateIn288, !- Erl Variable 1 Name
FlowrateOut288, !- Erl Variable 2 Name
FlowrateIn289, !- Erl Variable 3 Name
FlowrateOut289; !- A4
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
> Hi Sam, I got that working nicely, but can one somehow also modulate with m3/s or ACH? I still get very hi ACH, where the occupant would close the window.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "samuel.brunswick" <samuel.brunswick@> wrote:
> >
> > Hi Jean,
> >
> > You may be seeing high ACH because your surface control is set to 'Constant'. Constant means that the window is open all the way (ie open factor = 1 or no modulation), whenver the availability schedule is non-zero. If you want the window open area to modulate based on dT you have two options. First, if you set the surface control type to 'ZoneLevel' it will modulate the window open area based on the modulation logic described in your AirflowNetwork:MultiZone:Zone object. Second, if you set the surface control type to 'Temperature' it will follow the modulation logic described in your AirflowNetwork:MultiZone:Surface object. You might have to adjust your dT's for minimum and maximum opening factors (for instance, 15degC for minimum venting factor may be a little large).
> >
> > It might be useful to output the open factor for the window so you can see whether it is modulating or not:
> >
> > Output:Variable,
> > *, !- Key Value
> > Window/Door Venting Opening Factor , !- Variable Name
> > hourly; !- Reporting Frequency
> >
> > Hope this helps,
> >
> > Sam
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@> wrote:
> > >
> > > hi All, I'm seeing large air change rates (10-20 ACH) when the outdoor temp is at 7 degC and indoor temp is at 21 degC. The "Zone" level control is set for dT of 5 degC and the "surface" level control is set for "constant". See below...please advise.
> > >
> > > AirflowNetwork:MultiZone:Zone,
> > > 118129, !- Zone Name
> > > Temperature, !- Ventilation Control Mode
> > > 20001, !- Ventilation Control Zone Temperature Setpoint Schedule Name
> > > 0, !- Minimum Venting Open Factor {dimensionless}
> > > 0, !- Indoor and Outdoor Temperature Difference Lower Limit For Maximum Venting Open Factor {deltaC}
> > > 5, !- Indoor and Outdoor Temperature Difference Upper Limit for Minimun Venting Open Factor {deltaC}
> > > , !- Indoor and Outdoor Enthalpy Difference Lower Limit For Maximum Venting Open Factor {deltaJ/kg}
> > > , !- Indoor and Outdoor Enthalpy Difference Upper Limit for Minimun Venting Open Factor {deltaJ/kg}
> > > 12345; !- Venting Availability Schedule Name
> > >
> > > AirflowNetwork:MultiZone:Surface,
> > > P_118129_1_0_0_0_0_0_Win,!- Surface Name
> > > P_118129_1_0_0_0_0_0_Win,!- Leakage Component Name
> > > P_118129_1_0_0_0_0_0_Win,!- External Node Name
> > > 1, !- Window/Door Opening Factor, or Crack Factor {dimensionless}
> > > Constant, !- Ventilation Control Mode
> > > 20001, !- Ventilation Control Zone Temperature Setpoint Schedule Name
> > > .01, !- Minimum Venting Open Factor {dimensionless}
> > > 0, !- Indoor and Outdoor Temperature Difference Lower Limit For Maximum Venting Open Factor {deltaC}
> > > 15, !- Indoor and Outdoor Temperature Difference Upper Limit for Minimun Venting Open Factor {deltaC}
> > > , !- Indoor and Outdoor Enthalpy Difference Lower Limit For Maximum Venting Open Factor {deltaJ/kg}
> > > , !- Indoor and Outdoor Enthalpy Difference Upper Limit for Minimun Venting Open Factor {deltaJ/kg}
> > > 2; !- Venting Availability Schedule Name
> > >
> >
>
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