Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page

# How to override surface temperaure

I want to override the temperature of surfaces (BuildingSurface:Detailed) with Schedule:File. I won't detail the reason here, but it's just for modelling simplification of high-rise buildings with conditioned floors and unconditioned floors.

It's easy to set the floor/ceiling surfaces of the Typical floor as Adiabatic, but I want to do a little more accurate modeling.

When I look at the edd file, the Component Type "Surface" has only the following Control Types. I can't choose the surface temperature as Actuator.

• Construction State,[ ]
• ExteriorSurface Convection Heat Transfer Coefficient,[W/m2-K]
• Interior Surface Convection Heat Transfer Coefficient,[W/m2-K]
• View Factor To Ground,[ ]
• Outdoor Air Drybulb Temperature,[C]
• Outdoor Air Wetbulb Temperature,[C]
• Outdoor Air Wind Speed,[m/s]
• Outdoor Air Wind Direction,[degree]

Therefore, I came up with the following workaround.

I decided to override Outdoor Air Drybulb Temperature of the surface. Outside Boundary Condition of the surface was set to Outdoors (NoSun and NoWind). However, the surface temperature is different from the outdoor air temperature.

In order to minimize the effect of the outside Air Film, Outside Convection Coefficient of the surface was set to 1000W/m2-K which is the maximum value that can be entered.

BuildingSurface:Detailed,
2to50F_Office_1_Floor,  !- Name
FLOOR,                   !- Surface Type
Interior_Floor,   !- Construction Name
2to50F_Office_1,  !- Zone Name
,                        !- Space Name
Outdoors,                !- Outside Boundary Condition
,                        !- Outside Boundary Condition Object
NoSun,                   !- Sun Exposure
NoWind,                  !- Wind Exposure
autocalculate,           !- View Factor to Ground
4,                       !- Number of Vertices
-154.48095703125,        !- Vertex 1 X-coordinate {m}
-66.984489440917969,     !- Vertex 1 Y-coordinate {m}
123.80000305175781,      !- Vertex 1 Z-coordinate {m}
-155.17350769042969,     !- Vertex 2 X-coordinate {m}
-64.064559936523438,     !- Vertex 2 Y-coordinate {m}
123.80000305175781,      !- Vertex 2 Z-coordinate {m}
-150.95506286621094,     !- Vertex 3 X-coordinate {m}
-63.064018249511719,     !- Vertex 3 Y-coordinate {m}
123.80000305175781,      !- Vertex 3 Z-coordinate {m}
-150.26249694824219,     !- Vertex 4 X-coordinate {m}
-65.983940124511719,     !- Vertex 4 Y-coordinate {m}
123.80000305175781;      !- Vertex 4 Z-coordinate {m}

SurfaceProperty:ConvectionCoefficients,
2to50F_Office_1_Floor,  !- Surface Name
Outside,                 !- Convection Coefficient 1 Location
Value,                   !- Convection Coefficient 1 Type
1000;                    !- Convection Coefficient 1 {W/m2-K}


After that, I wrote a small EMS program to override the Outdoor Air Drybulb Temperature. The simulation result looks ok. The surface temperature became almost the same value as the temperature in Schedule:File.

Is there a better way to override the surface temperature?

edit retag close merge delete

1

Hey @Keigo. Did you consider OtherSideCoefficients as an option? From what you describe, I think it could be easier - no need to bring in EMS. Maybe I'm missing something.

( 2023-09-16 15:29:22 -0500 )edit

@Denis Bourgeois I want all the conditioned floors on the left side of the atachetd image to be represented by one typical floor with multiplier on the right. It is very difficult to properly adjust the heat transfer coefficient of the floor/ceiling of the typical floor on the right because the typical floor is adjacent to outdoors while the actual conditioned floors on the left are not exposed to outdoors. There is heat transfer between the conditioned floor and the unconditioned floor. I want to take the heat transfer into account with one typical floor model.

( 2023-09-16 18:57:48 -0500 )edit
1

@Keigo the OtherSideCoefficients object type has a constant temperature field for "...either of the surface or outside air temperature." This can also be defined via schedule. The tricky part is knowing what value to apply to all the other heat transfer parameters of the object.

( 2023-09-18 09:35:22 -0500 )edit

Also, wouldn't you want an unmultiplied top and bottom floor surrounding the multiplied typical floor in the middle? The typical floor should be adjacent to outdoors only at the walls, not the floor or ceiling surfaces.

( 2023-09-18 09:36:34 -0500 )edit
1

@Denis Bourgeois@Aaron Boranian You guys are right. I didn't know SurfaceProperty:OtherSideCoefficients could specify the surface temperature, given its class name. Thank you for your answer!

( 2023-09-25 22:13:37 -0500 )edit

Sort by ยป oldest newest most voted

@Denis Bourgeois and @Aaron Boranian answered my question. Below is just a memorandum of how to use SurfaceProperty:OtherSideCoefficients actually.

Only Name, Constant Temperature Schedule Name and Combined Convective/Radiative Film Coefficient should be input. Combined Convective/Radiative Film Coefficient should be 0. Other fields can be the default values.

SurfaceProperty:OtherSideCoefficients,
SurfaceProperty_FloorTemp,  !- Name
0,                       !- Combined Convective/Radiative Film Coefficient {W/m2-K}
,                        !- Constant Temperature {C}
1,                       !- Constant Temperature Coefficient
,                        !- External Dry-Bulb Temperature Coefficient
,                        !- Ground Temperature Coefficient
,                        !- Wind Speed Coefficient
,                        !- Zone Air Temperature Coefficient
ScheduleFile_HourlyFloorSurfaceTemp,  !- Constant Temperature Schedule Name
No,                      !- Sinusoidal Variation of Constant Temperature Coefficient
24;                      !- Period of Sinusoidal Variation {hr}

Schedule:File,
ScheduleFile_HourlyFloorSurfaceTemp,  !- Name
,                        !- Schedule Type Limits Name
C:\Project\XXXXX\ScheduleFile_HourlyFloorSurfaceTemp.csv,  !- File Name
2,                       !- Column Number
1,                       !- Rows to Skip at Top
8760,                    !- Number of Hours of Data
Comma,                   !- Column Separator
No,                      !- Interpolate to Timestep
60;                      !- Minutes per Item


Change Outside Boundary Condition of the relevant surfaces in BuildingSurface:Detailed to OtherSideCoefficients, and input the Name of SurfaceProperty:OtherSideCoefficients to Outside Boundary Condition Object.

BuildingSurface:Detailed,
2to50F_Office_1_Floor,  !- Name
FLOOR,                   !- Surface Type
Interior_Floor,   !- Construction Name
2to50F_Office_1,  !- Zone Name
,                        !- Space Name
OtherSideCoefficients,   !- Outside Boundary Condition
SurfaceProperty_FloorTemp,  !- Outside Boundary Condition Object
NoSun,                   !- Sun Exposure
NoWind,                  !- Wind Exposure
autocalculate,           !- View Factor to Ground
4,                       !- Number of Vertices
-154.48095703125,        !- Vertex 1 X-coordinate {m}
-66.984489440917969,     !- Vertex 1 Y-coordinate {m}
123.80000305175781,      !- Vertex 1 Z-coordinate {m}
-155.17350769042969,     !- Vertex 2 X-coordinate {m}
-64.064559936523438,     !- Vertex 2 Y-coordinate {m}
123.80000305175781,      !- Vertex 2 Z-coordinate {m}
-150.95506286621094,     !- Vertex 3 X-coordinate {m}
-63.064018249511719,     !- Vertex 3 Y-coordinate {m}
123.80000305175781,      !- Vertex 3 Z-coordinate {m}
-150.26249694824219,     !- Vertex 4 X-coordinate {m}
-65.983940124511719,     !- Vertex 4 Y-coordinate {m}
123.80000305175781;      !- Vertex 4 Z-coordinate {m}


EMS is necessary only for overriding Schedule:File during SummerDesignDay and WinterDesignDay.

more

Please start posting anonymously - your entry will be published after you log in or create a new account.