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RE: [EnergyPlus_Support] Re: AFN - Nat Vent Too much during cold / warm days
The opening factor can be modulated only. The flow rates are calculated
based on opening factor, pressure difference, wind speed and direction.
If ACH is too large through windows, it is possible to reduce the values of
the Window/Door Opening Factor, or Crack Factor {dimensionless} field in the
AirflowNetwork:MultiZone:Surface object.
Hope this helps.
Lixing
-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
Sent: Friday, August 05, 2011 6:44 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: AFN - Nat Vent Too much during cold / warm
days
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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