# 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:

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

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

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

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

• Tgrnd = Temperature of the ground (°C) Wspd = 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
,                        !- 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;