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# How can I connect to adjacent zones to have an Heat Transfer?

Hello EnergyPlus-Users,

I use the IDF Editor and I don't understand how I can connect two adjacent zones to have an heat Transfer. My Building is quite simple, it has just two zones. One living room and one attic. I already red the documentation, but I didn’t understood it well. It would be very nice if anyone can help me. I think the Problem is not that hard actually, but I am a beginner and do my Bachelor in Building Simulation. Thank you and Kind regards,

Arne Hübner

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The heat transfer between your 2 zones is in the surface objects. These 2 surfaces separate the zone and the plenum above that zone. Notice the Outside Boundary Condition in each object = surface. Also note that the Outside Boundary Condition Object input (e.g., CPFloor 05) points to the name of the other surface. These 2 surfaces are mirror images of each other and each constitute one of the walls in their respective zones. The Zone Name input shows which zone the surface is part of. The heat transfer will be through these surfaces.

BuildingSurface:Detailed,
Ceiling 05,                             !- Name
Ceiling,                                !- Surface Type
Acoustic Tile,                          !- Construction Name
Zone_00_05,                             !- Zone Name
Surface,                                !- Outside Boundary Condition
CPFloor 05,                             !- Outside Boundary Condition Object
NoSun,                                  !- Sun Exposure
NoWind,                                 !- Wind Exposure
autocalculate,                          !- View Factor to Ground
4,                                      !- Number of Vertices
47, 3, 3,                               !- X,Y,Z Vertex 1 {m}
47, 47, 3,                              !- X,Y,Z Vertex 2 {m}
3, 47, 3,                               !- X,Y,Z Vertex 3 {m}
3, 3, 3;                                !- X,Y,Z Vertex 4 {m}

BuildingSurface:Detailed,
CPFloor 05,                             !- Name
Floor,                                  !- Surface Type
Rev - Acoustic Tile,                    !- Construction Name
Ceiling_Plenum_Zone_00_05,              !- Zone Name
Surface,                                !- Outside Boundary Condition
Ceiling 05,                             !- Outside Boundary Condition Object
NoSun,                                  !- Sun Exposure
NoWind,                                 !- Wind Exposure
autocalculate,                          !- View Factor to Ground
4,                                      !- Number of Vertices
3, 3, 3,                                !- X,Y,Z Vertex 1 {m}
3, 47, 3,                               !- X,Y,Z Vertex 2 {m}
47, 47, 3,                              !- X,Y,Z Vertex 3 {m}
47, 3, 3;                               !- X,Y,Z Vertex 4 {m}


After you run your simulation look in the rdd (report data dictionary) file for available reports specific to your simulation. You must include the Output:VariableDictionary, Regular; You will see reports related to surfaces. There are many different reports for surface temperature, heat transfer rate, gain, and loss, etc. This is the standard syntax for the rdd file contents.

Zone,Average,Surface Inside Face Temperature [C]
Zone,Average,Surface Outside Face Temperature [C]

Zone,Average,Surface Inside Face Conduction Heat Transfer Rate [W]
Zone,Average,Surface Inside Face Conduction Heat Gain Rate [W]
Zone,Average,Surface Inside Face Conduction Heat Loss Rate [W]
Zone,Average,Surface Inside Face Conduction Heat Transfer Rate per Area [W/m2]
Zone,Sum,Surface Inside Face Conduction Heat Transfer Energy [J]

Zone,Average,Surface Outside Face Conduction Heat Transfer Rate [W]
Zone,Average,Surface Outside Face Conduction Heat Gain Rate [W]
Zone,Average,Surface Outside Face Conduction Heat Loss Rate [W]
Zone,Average,Surface Outside Face Conduction Heat Transfer Rate per Area [W/m2]


If you turn on output formatting for the rdd file you will get reports already set up for your input file. Use Output:VariableDictionary, IDF; and you will get reports that look like this.

Output:Variable,*,Surface Inside Face Temperature, Hourly;


You can change the report frequency to detailed, timestep, hourly, daily, monthly, runperiod, environment or annual.

Use these reports to view the heat transfer through these surfaces.

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Thank you rraustad! I don't get any errors anymore. But if I use the Output "Surface Inside Face Conduction Heat Loss Rate [W]" I have 0 values in the surface Floor and just values in the surface Ceiling.

( 2019-10-01 09:03:04 -0600 )edit

Check the Outside Boundary Condition for the floor surface to see if it is set as Adiabatic. If so, you can change it to Ground and then you should see heat transfer. You will also need to set proper ground temperatures for your geography. Do an advanced search for "ground temperature" in all the pdf's in the documentation folder.

( 2019-10-01 09:12:56 -0600 )edit

Okay but the floor of the attic doesn't touch the ground.

( 2019-10-01 09:15:21 -0600 )edit

Right now the Outside Boundary Conditions for both surfaces are set on "Surfaces".

( 2019-10-01 09:16:50 -0600 )edit

When you say floor you mean the attic zone surface? I thought you were talking about the floor in the zone next to the ground. Match the name of the surface output reports to your building model surface names, is the ceiling surface name = "Floor"?

( 2019-10-01 14:44:20 -0600 )edit