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Simulating a single room + radiator in EnergyPlus

asked 2016-02-15 01:13:10 -0600

updated 2016-02-15 10:29:23 -0600

Hi there,

I want to simulate a single room with a simple radiator. To do so, I have applied "ZoneHVAC:Baseboard:Convective:Water" + boiler in a loop. The simulation doesn't have any problem, however, in the reported outputs the variable "Zone Air System Sensible Heating Energy" is not zero!!!! Does it mean that another heat supplier (with air flow) in addition to the radiator is considered in the simulation???

Thanks in advance

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Where do you see the "Zone Air System Sensible Heating Energy"? HTML table, CSV, ?

Aaron Boranian gravatar imageAaron Boranian ( 2016-02-15 11:20:22 -0600 )edit

"Zone Air System Sensible Heating Energy" is a variable in Output:Variable, and I saw the value of this variable in the released spreadsheet.

Misagh Ebrahimpour gravatar imageMisagh Ebrahimpour ( 2016-02-15 11:47:52 -0600 )edit

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answered 2016-02-15 12:25:12 -0600

Sounds like you are including the Zone object's output for "Zone Air System Sensible Heating Energy". According to the documentation, this output:

Reports the heating or cooling delivered by the HVAC system to a zone. These values are calculated by multiplying the supply air mass flow rate by the difference between the supply air temperature and the zone air temperature. This does not always indicate the operation of heating or cooling coils. For example, cooling will be reported if the supply air is cooled due to the introduction of outside air, even if all coils are off.

In other words, even if you model an air loop without central heating or terminal reheat, when the air terminal delivers supply air that is hotter than the zone's air, this will be reported as positive sensible heating for this output variable.

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I have considered "ZoneHVAC:Baseboard:Convective:Water" and a boiler in a loop because I just want to have the radiator as the heat supplier. I have not considered anything related to Air supply. I dont know why this Air supply is added to the system. It might be due to the zone autosizing, but I am not sure about it.

Misagh Ebrahimpour gravatar imageMisagh Ebrahimpour ( 2016-02-15 12:57:45 -0600 )edit

It doesn't have to be a central air supply, it could be zone-level HVAC (window AC, FCU, etc.) or possibly Ideal Loads Air System. Set the first 5 input fields of the "SimulationControl" object to 'Yes', then set the 'Reporting Frequency' field of the Output:Variable object to "Hourly" or "Detailed". Run a simulation, then check the times where the output CSV file report non-zero sensible heating. This is how you determine whether it occurs for sizing periods, the entire simulation with the weather file, or both.

Aaron Boranian gravatar imageAaron Boranian ( 2016-02-15 14:16:08 -0600 )edit

The value of "Zone Air System Sensible Heating Energy" is not zero in sizing and run period. There isnt any central air supply nor any other air supplier. Can I send you the idf file in a way?

Misagh Ebrahimpour gravatar imageMisagh Ebrahimpour ( 2016-02-15 15:56:09 -0600 )edit

Sure, can you put it on Dropbox so that I can download it? If not, my email is aaron.boranian@bigladdersoftware.com. If there are any files that the IDF references (schedule, ground temperatures, etc.) I will need those as well to run a simulation.

Aaron Boranian gravatar imageAaron Boranian ( 2016-02-15 16:24:02 -0600 )edit

I sent an email.

Misagh Ebrahimpour gravatar imageMisagh Ebrahimpour ( 2016-02-15 23:28:22 -0600 )edit

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Asked: 2016-02-15 01:13:10 -0600

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Last updated: Feb 15 '16