Program options - EnergyPlus

EnergyPlus tab of the Program options dialog

EnergyPlus

You can select the version of EnergyPlus to use in your simulations. This can be useful to target a specific DOE version you may wish to use or when a new version becomes available which might provide new functionality or address previous problems.

You should generally select the recommended DLL option as it is more tightly integrated within DesignBuilder and provides progress feedback.

DesignBuilder comes with 2 internal versions of EnergyPlus:

• DLL - the default option, runs the internal version of EnergyPlus supplied with the program asynchronously giving visual feedback of progress and allowing interaction with the computer during the simulation.
• Executable - an executable version of the program running in a command window.

Alternatively you can select an executable version of EnergyPlus supplied by DOE. If you are exporting IDF data for use outside DesignBuilder you should select the appropriate DOE version to avoid incompatibilities.

Note: the EnergyPlus version selected here is used for simulations within DesignBuilder but also as the target version when exporting IDF data for use outside DesignBuilder.

Mode

If you select an executable version (internal or DOE) there are four options available to control the way EnergyPlus is executed when simulating within DesignBuilder:

• 1-Executable (minimised) - runs the executable invisibly - you will just see a minimised window on the Task bar but not the EnergyPlus command window.
• 2-Executable (visible) - runs the executable showing EnergyPlus screen output in a command window.
• 3-Executable (debug) - runs the executable showing EnergyPlus screen output in a command window and pauses after simulation - intended for advanced EnergyPlus users who may want to see the stack dump following a crash.
• 4-Executable (EP-Launch) - runs the DOE-supplied EP-Launch program, waiting until this is closed before loading results. This option is only possible if you have selected a DOE-supplied version of the EnergyPlus executable. This option can be useful for making quick minor changes to the IDF data prior to simulation.  Any changes made to the IDF data from within EP-Launch will be included in the simulation but will not be retained for future simulations. Info on the EP-Launch option.

   

  The screenshot below shows EP-Launch being used to control EnergyPlus simulations from DesignBuilder.

   

  

   

  Note 1: If you use this method you must make sure to set the correct weather file manually.

  Note 2: Any changes you make to the IDF data, either in the IDF Editor or using a text editor, will be saved in a file called ip.inp in the EnergyPlus folder. This file will be overwritten the next time a simulation is requested so if you wish to save the any changes you make to IDF data you should use the File > Export option and edit the data and make simulations outside DesignBuilder.

  Note 3: If you want to run EnergyPlus without DesignBuilder then use the File > Export > Export EnergyPlus IDf file > Simulation option to generate the idf file and load this using EP-Launch outside DesignBuilder.

EnergyPlus export folder

When using a DOE EnergyPlus executable version you must also select the folder where the selected version is installed. You can scan the disk for DOE installations by clicking on the link in the Info help panel..

When you select any option other than the default DLL option, the necessary EnergyPlus files are downloaded seamlessly prior to the first simulation following the change.

Note: If you wish to install a different DLL version of EnergyPlus to that which is recommended, you must have administrative rights on the computer.

DesignBuilder are licensed distributors of EnergyPlus.   All versions of EnergyPlus supplied by DesignBuilder have been compiled by the DOE.

Program control

Maximum number of threads

You can control the number of threads to be used per EnergyPlus simulation. The default is 1 thread. In cases where a larger number of threads is entered, you may find that the computer becomes less response when EnergyPlus simulations are running. If this becomes a problem you should enter a lower value here.

Output file

Save ESO simulation output

You can generate ESO output files containing Heating design, Cooling design and Simulation results. The files can be loaded later using the File > Load results file menu option, provided the model hasn't changed too much.

Rules:

1. The DesignBuilder model must still have same zones and surfaces it had at the time the simulation data was generated
2. If you have modified these files and carried out further simulations in EnergyPlus you should find that the results will read in OK provided you haven't changed zone or surface names in the IDF data.
3. You cannot read in ESO files generated from IDF data which was entered by hand (or by other software) because the zone and surface references will be different.
4. Results must be loaded to the correct screen - you can't for example read Heating design results into the Simulation screen.
5. Simulation only: the results to be read in must have been generated using the same simulation period and number of timesteps currently set in the Simulation options.

If you choose to Save ESO simulation output then you can also select options to Prompt for filename and Auto load ESO described below.

Prompt for filename

Tell DesignBuilder whether you wish to be prompted for a filename after each simulation.  If you choose not to be prompted then DesignBuilder will automatically generate output filenames based on the name of the dsb file, the calculation type, the calculation description and the date. It places the file in the EnergyPlus folder.  If you choose to be prompted the file can be stored anywhere on your computer system.

Auto load ESO

Check this option to automatically load the ESO results file after simulations. If you have been warned that there will be a lot of data and the program may crash on reading results you may wish to switch this option off and reload the results later. It is often possible to read in very large ESO files after DesignBuilder has restarted following a simulation and this can be a useful for avoiding a crash due to too much data. You may also wish to switch the option off to avoid waiting for the results to read in when carrying out parametric simulations.

This option only refers to Simulation results no Heating/Cooling Design results.

IDF Options

Display extra warnings

Requesting Display extra warnings causes the statement:

Diagnostics,DisplayExtraWarnings;

to be included in the IDF data. This option is for experienced EnergyPlus users who understand the significance of the extra warning messages generated.

IDF Formatting

The IDF data can be formatted using the options:

• 1-Full - indentation and comments are included in the IDF data
• 2-Basic - just indentation and comments required to reference the IDF objects with data in the DesignBuilder model.
• 3-Compressed - the IDF data is fully compressed. Choose this option if your model is very large and you wish to reduce the amount of IDF text being processed. When the IDF data uses more than about 10MB of disk space DesignBuilder is unable to process the quantity of text involved and if this happens when the 1-Full or 2-Basic options are set it will attempt to regenerate the IDF data using the 3-Compressed option to reduce the memory requirement. If IDF data is being generated twice before your simulations you can speed the process by selecting this option from the start ensuring that IDF data is only generated once.