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Energy consumption does not change with different wall construction

asked 2018-12-09 21:18:53 -0500

wendigoZ's avatar

updated 2018-12-27 10:08:36 -0500

I assigned three thermal zones and set up all the building construction in OpenStudio. when I run the simulation, I found the U-value of wall, roof and floor do not affect the total energy consumption of my model. No matter what U-value I use, the model output stays the same.

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It's possible that either constructions are not assigned correctly, or HVAC is not set up correctly so that it is not being affected by envelope (like missing thermostats).

egillmor's avatar egillmor  ( 2018-12-10 09:19:27 -0500 )edit

Can you send your files? Especially the E+ IDF file and the errors and warnings file.

Ehsank's avatar Ehsank  ( 2018-12-10 11:29:55 -0500 )edit

Thank you both of egillmor and Ehsank for replying. here is my model:

also, when I export the model to IDF file, it says two of the spaces cannot be converted as they do not have a thermal zone. These two spaces are the overall layout of the building so I did not assign any thermal zone to them. Is it a problem?


Warnings occurred on translation to EnergyPlus

Warning: Space Space 101 is not associated with a ThermalZone, it will not be translated.

Warning: Space Space 1 is not associated with a ThermalZone, it wi

wendigoZ's avatar wendigoZ  ( 2018-12-10 12:28:20 -0500 )edit

I don't have the software to open a .rar file on this machine, but yes that is a problem.
This is an old tutorial but I think it's still valid.

egillmor's avatar egillmor  ( 2018-12-10 12:39:53 -0500 )edit

Dear egillmor,

here is the link for all the file:

Done, I have set up all the thermal states and thermal zone. thank you. my result of energy consumption is double now. is it normal?

wendigoZ's avatar wendigoZ  ( 2018-12-10 12:50:33 -0500 )edit

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answered 2018-12-11 00:06:54 -0500

I checked your model. There was no thermal zone, construction set, and schedule set assigned to two of the spaces you had. After applying some values from your library (I picked them randomly since I don't have enough info about your model's properties), I increased the thermal conductivity of your "Netzero wall", which is the main wall assembly in your model and the total energy consumption bumped up accordingly. So, you should double check all the spaces you have and make sure correct properties are assigned to them. The rest of the model seems to be correct.

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Asked: 2018-12-09 21:18:53 -0500

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Last updated: Dec 09 '18