Tips and Tricks for Using EnergyPlus — EnergyPlus 8.3

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Using OSC (Other Side Coefficients) to create controlled panels[LINK]

The Other Side Coefficient (OSC) equation permits setting either the outside surface temperature or the outside air temperature to a constant value or a scheduled value based on the size of the first input parameter, N1. The original temperature equation was:

where:

= Outside Air Temperature when N1 (Combined convective/radiative film Coeff) > 0

= Exterior Surface Temperature when N1 (Combined convective/radiative film Coeff) <= 0

= MAT = Temperature of the zone being simulated (°C)

= Dry-bulb temperature of the outdoor air (°C)

= Temperature of the ground (°C)

= Outdoor wind speed (m/sec)

The coefficients N2, N3, N4, N6, and N7 scale the contribution of the various terms that follow them. In the case of N4, it is followed by another term N5. This is a constant temperature that can also be overridden by a scheduled value. Note that in some EnergyPlus documentation, the N’s are given as C’s.

This object has been changed to permit the outside temperature, T, to be controlled to a set point temperature that is specified as N5 or comes from the schedule A2.

Note that since the surface that contains the panel subsurfaces (that must be called doors in EnergyPlus) receives that same outside temperature as the panels, it should have a construction with a very high thermal resistance to essentially take it out of the room heat balance calculation.

An Example input file object is shown below.

SurfaceProperty:OtherSideCoefficients,
   Zn001:Roof001:OSC, !- Name
   0,   ! (N1) Combined Convective/Radiative Film Coefficient {W/m2-K}
   0,   ! (N5) Constant Temperature {C}
   0.95,!(N4) Constant Temperature Coefficient
   ,    ! (N3)External Dry-Bulb Temperature Coefficient
   ,    ! (N6)Ground Temperature Coefficient
   ,    ! (N7)Wind Speed Coefficient
   -.95,! (N2) Zone Air Temperature Coefficient
   ConstantCooling,     ! (A2) Constant Temperature Schedule Name
   No,  ! (A3)Sinusoidal Variation of Constant Temperature Coefficient
   24,  ! (N8)Period of Sinusoidal Variation {hr}
   1.,  ! (N9)Previous Other Side Temperature Coefficient
   5.,  !(N10) Minimum Other Side Temperature Limit
   25.; ! (N11) Maximum Other Side Temperature Limit

This object results in the following equation for T:

T = 1.0*Tlast +0.95*(Tsetpoint - TzoneAir) (with limits)

The result of this is that the surface temperature, T, will be changed to the temperature that will force the zone air temperature to the setpoint providing the temperature limits are not reached. When the zone air temperature is at the setpoint, T remains at the value it had in the prior time step.

A complete example with all pertinent objects:

Construction,
    PanelConst,              !- Name
    Std Steel_Brown_Regular; !- Outside Layer

  Material,
    Std Steel_Brown_Regular, !- Name
    Smooth,                  !- Roughness
    1.5000000E-03,           !- Thickness {m}
    44.96960,                !- Conductivity {W/m-K}
    7689.000,                !- Density {kg/m3}
    418.0000,                !- Specific Heat {J/kg-K}
    0.9000000,               !- Thermal Absorptance
    0.9200000,               !- Solar Absorptance
    0.92000000;              !- Visible Absorptance

  BuildingSurface:Detailed,
    Zn001:Roof001,           !- Name
    Roof,                    !- Surface Type
    ROOF31,                  !- Construction Name
    ZONE ONE,                !- Zone Name
    OtherSideCoefficients,   !- Outside Boundary Condition
    Zn001:Roof001:OSC,       !- Outside Boundary Condition Object
    NoSun,                   !- Sun Exposure
    NoWind,                  !- Wind Exposure
    0,                       !- View Factor to Ground
    4,                       !- Number of Vertices
    0.000000,15.24000,4.572,  !- X,Y,Z ==> Vertex 1 {m}
    0.000000,0.000000,4.572,  !- X,Y,Z ==> Vertex 2 {m}
    15.24000,0.000000,4.572,  !- X,Y,Z ==> Vertex 3 {m}
    15.24000,15.24000,4.572;  !- X,Y,Z ==> Vertex 4 {m}

  FenestrationSurface:Detailed,
    panel002,                !- Name
    Door,                    !- Surface Type
    PanelConst,              !- Construction Name
    Zn001:Roof001,           !- Building Surface Name
    ,                        !- Outside Boundary Condition Object
    autocalculate,           !- View Factor to Ground
    ,                        !- Shading Control Name
    ,                        !- Frame and Divider Name
    1,                       !- Multiplier
    4,                       !- Number of Vertices
    3,2,4.572,  !- X,Y,Z ==> Vertex 1 {m}
    3,3,4.572,  !- X,Y,Z ==> Vertex 2 {m}
    4,3,4.572,  !- X,Y,Z ==> Vertex 3 {m}
    4,2,4.572;  !- X,Y,Z ==> Vertex 4 {m}

  SurfaceProperty:OtherSideCoefficients,
    Zn001:Roof001:OSC,       !- Name
    0,            !- Combined Convective/Radiative Film Coefficient {W/m2-K}
    0,                       !- Constant Temperature {C}
    0.95,                    !- Constant Temperature Coefficient
    ,                        !- External Dry-Bulb Temperature Coefficient
    ,                        !- Ground Temperature Coefficient
    ,                        !- Wind Speed Coefficient
    -.95,                    !- Zone Air Temperature Coefficient
    ConstantTwentyTwo,       !- Constant Temperature Schedule Name
    No,           !- Sinusoidal Variation of Constant Temperature Coefficient
    24,                      !- Period of Sinusoidal Variation {hr}
    1.,                      !- Previous Other Side Temperature Coefficient
    5.,                      !- Minimum Other Side Temperature Limit {C}
    25.;                     !- Maximum Other Side Temperature Limit {C}

Schedule:Constant,ConstantTwentyTwo,PanelControl,22;