Using OSC (Other Side Coefficients) to create controlled panels¶

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:

\[T = N_2 T_{zone} + N_3 T_{oadb} + N_4 N_5 + N_6 T_{grnd} + N_7 W_{spd} T_{oadb}\]

where:

\(T\) = Outside Air Temperature when N1 (Combined convective/radiative film Coeff) > 0
\(T\) = Exterior Surface Temperature when N1 (Combined convective/radiative film Coeff) \< = 0
\(T_{zone}\) = MAT = Temperature of the zone being simulated (°C)
\(T_{oadb}\) = Dry-bulb temperature of the outdoor air (°C)
\(T_{grnd}\) = Temperature of the ground (°C) Wspd = Outdoor wind speed (m/sec)

The coefficients N\(_{2}\), N\(_{3}\), N\(_{4}\), N\(_{6}\), and N\(_{7}\) scale the contribution of the various terms that follow them. In the case of N\(_{4}\), it is followed by another term N\(_{5}\). 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 N\(_{5}\) 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;