Minimum Indoor Temperature in ZoneVentilation:WindandStackOpenArea does not work

asked 2022-01-25 22:17:45 -0500

Keigo's avatar

updated 2022-10-12 20:56:20 -0500

The problem is as per the title. My energy model is a office building located in a subtropical climate. Air-conditioning is cooling for most of the year with little heating. HVAC sytem is VAV:Reheat.

The purpose of using ZoneVentilation:WindandStackOpenArea is to roughly estimate the cooling energy saving by natural ventilation. My input is as follows:

ZoneVentilation:WindandStackOpenArea,
    WSOA_19F_Office_E,    !- Name
    19F_Office_E,         !- Zone Name
    6.068,                   !- Opening Area {m2}
    ALWAYS ON,               !- Opening Area Fraction Schedule Name
    autocalculate,           !- Opening Effectiveness {dimensionless}
    43.384,                  !- Effective Angle {deg}
    0,                       !- Height Difference {m}
    autocalculate,           !- Discharge Coefficient for Opening
    21,                      !- Minimum Indoor Temperature {C}
    ,                        !- Minimum Indoor Temperature Schedule Name
    100,                     !- Maximum Indoor Temperature {C}
    ,                        !- Maximum Indoor Temperature Schedule Name
    -100,                    !- Delta Temperature {deltaC}
    ,                        !- Delta Temperature Schedule Name
    12,                      !- Minimum Outdoor Temperature {C}
    ,                        !- Minimum Outdoor Temperature Schedule Name
    23,                      !- Maximum Outdoor Temperature {C}
    ,                        !- Maximum Outdoor Temperature Schedule Name
    40;                      !- Maximum Wind Speed {m/s}

Opening Area Fraction Schedule cannot be left blank. So, I put "ALWAYS ON" (always "1").

Indoor Cooling Setpoint is 23°C and Indoor Heating Setpoint is 20°C. Thus, the indoor temperature between 20°C to 23°C is a dead band.

I set Minimum Indoor Temperature 21°C in order to prevent natural ventilation while Zones are heated by reheat coil. However, Minimum Indoor Temperature doesn't work. Natural ventilation is not turned off even when the indoor temperature is below 21°C. Cold outdoor air comes in and reheat coils keep heating zones, which result in incredibly large heating end use.

Below charts are just examples of one zone in different seasons. image description

image description

In the first chart "Winter", Zone Ventilation is On and the zone has large ACH even when indoor temperature is below 21°C. The reheat coil tries to keep indoor setpoint 20°C and heats the zone. I confirmed that other temperature settings such asMinimum Outdoor Temperature and Maximum Outdoor Temperature work fine, but Minimum Indoor Temperature does not work. Is this a bug?

Or should I use AvailabilityManager:HybridVentilation? But accrding to I/O Reference, AvailabilityManager:HybridVentilation is not for ZoneVentilation:WindandStackOpenArea.

The model was created by EnergyPlus 8.9.0, but I couldn't find any "Defects Repaired" about ZoneVentilation:WindandStackOpenArea for newer versions.

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Comments

I did find a bugfix related to this, but it suggests it was fixed prior to EnergyPlus 8.9.

shorowit's avatar shorowit  ( 2022-01-26 09:07:25 -0500 )edit

Oh it's true, the bug was found 8 years ago! But I still have this bug in EnergyPlus 8.9.0...

Keigo's avatar Keigo  ( 2022-01-26 20:33:17 -0500 )edit

Any update on this? I face the same problem using EnergyPlus v.9. 4

Ricardo Gomes's avatar Ricardo Gomes  ( 2022-08-02 10:39:42 -0500 )edit

Unfortunately, no update.

Keigo's avatar Keigo  ( 2022-08-03 21:11:11 -0500 )edit

@Keigo indeed, it appears this is still a problem. I simulated a simple, single zone with electric heat. The window is opening below the minimum indoor temperature.

Ski90Moo's avatar Ski90Moo  ( 2023-02-25 21:33:53 -0500 )edit