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Can you access autosized values from PythonPlugin?

asked 2021-11-05 10:54:15 -0500

Vasek's avatar

updated 2022-02-18 16:57:00 -0500

Hi all,

I am wondering if it is possible to access autosized values from PythonPlugin, for example is it possible to access maximum water flow rate of coils? If so, how pls?

I read, that sizing values should be available as internal variables but I cannot find list of internal variables which can be queried from python plugin... I looked into *.edd file, there are some sizing values, but I have not found anything close to maximum water flow rate there...

Thank you!

    Basement VAV Box Reheat Coil,  !- Name
    ALWAYS_ON,               !- Availability Schedule Name
    AUTOSIZE,                !- U-Factor Times Area Value {W/K}
    AUTOSIZE,                !- Maximum Water Flow Rate {m3/s}
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answered 2021-11-05 11:31:40 -0500

updated 2021-11-05 14:48:21 -0500

Similar to actuators, internal variables in EMS are part of a pre-defined list -- you can only access the items that the development team has defined as a potential internal variable. This is why the EDD output file is generated based on the Output:EnergyManagementSystem object to include what actuators and internal variables are available for your IDF. You can read more in this post.

Most internal variables for HVAC systems are related to sizing or nominal rating conditions. In the case of water heating coils, it looks like there are no internal variables available at all.

An alternative to using EMS to get this information is to review the EIO output file. The EIO file has different sections, and the Component Sizing Information is where you can find the maximum water flow rate through a hot water coil. If you're already using the Python Plugin, you may be able to write a script to automate the process of parsing the EIO file for this information to then use somewhere else in your modeling workflow.

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To add on to this, if there are additional internal variables that you would find helpful, you can request them for a future EnergyPlus release at

shorowit's avatar shorowit  ( 2021-11-05 15:34:09 -0500 )edit

answered 2021-11-11 14:03:32 -0500

updated 2021-11-11 14:04:27 -0500

No, not during the simulation where it's being sized. However, after completing an initial simulation, the maximum water flow rate is listed in the output reports, including the database/SQL file (if requested). You can then run the simulation a second time, and this time you can query the sql file from the first simulation (assuming you saved a copy) in your Python script to pull the sized capacities/flow rates.

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The sizing values won't be internal variables, but you can make a new EMS variable and assign it the sized value. You wouldn't be able to adjust the sized value/flow rate of the coil, but you could use that value in your EMS program if needed.

ericmartinpe's avatar ericmartinpe  ( 2021-11-11 14:10:48 -0500 )edit

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Asked: 2021-11-05 10:54:15 -0500

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Last updated: Nov 11 '21