Program options - EnergyPlus

EnergyPlus tab of the Program options dialog

EnergyPlus

EnergyPlus version

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

Tip: You should generally use the recommended DLL option as it is tightly integrated with 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.

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.

Running a DOE Version of EnergyPlus

To run a version of EnergyPlus downloaded from the DOE website you should create a new EnergyPlus version using the Custom category and make the appropriate settings. The screenshot below shows the EnergyPlus tab on Program options in this case.

When doing this it is important to consider that the only versions officially supported by DesignBuilder are the ones in the DLL list, and of those, the only one that has been fully tested is the default DLL option. The other options provided should generally work but no guarantees are provided. You may also be able to create and use new custom EnergyPlus versions not listed under the DLL category if the IDF /ESO file input/output formats are the same as one of the options provided by DesignBuilder. In this case you should look out for possible problems with simulations not running or results not loading correctly.

Output file

Output file format

This option allows you to define the format of the EnergyPlus Summary "CSV" output file. Select from:

• 1-Auto - the default option where DesignBuilder selects either the appropriate option based on the machine locale. Normally it will use the tab format for machines using
• 2-Tab - ensures that EnergyPlus generates a file called eplustbl.tab in which the tab character is used to separate the values, regardless of the machine locale.
• 3-CSV - ensures that EnergyPlus generates a file called eplustbl.csv in which the comma (,) character is used to separate the values, regardless of the machine locale.

Save ESO simulation output

The ESO file is the primary output from EnergyPlus used by DesignBuilder to access simulation results. ESO output files will be generated by EnergyPlus following Heating design, Cooling design and Simulation calculations. You should normally leave this option checked to ensure that results are generated.

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

The ESO files can be loaded later using the File > Load results file menu option, provided the model hasn't changed too much. In this case the rules are as follows:

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.

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 not to Heating/Cooling Design results.

IDF Options

Store IDF files

When this option is checked the EnergyPlus IDF input file associated with the simulation is stored with model and can be accessed later even after the file in the EnergyPlus folder has been overwritten. This option is off by default to help conserve memory for other operations.

Display extra warnings

Requesting Display extra warnings causes the statement:

Diagnostics,DisplayExtraWarnings;

to be included in the IDF data. This option is intended for use by 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.

IDF Object Naming

IDF name type

Normally DesignBuilder uses human readable names in the IDF based on the names used in the model. However you can override this behaviour by changing this option. Select from:

• 1-User-defined - the default option where human readable user-defined names are used wherever possible in the IDF data.
• 2-Numeric - where machine-generated numeric Ids are used instead of readable names used in the model.

Note: If you are using an evaluation licence then the software behaves as if the 2-Numeric setting has been selected, regardless of the selection here.

Use material, construction and zone name names in IDF

You can override the overall way that IDF names are written specifically for materials, constructions and zones by checking/unchecking this checkbox.

Distance Between Site Location and Weather File

Check distance between site location and weather file

The locations defined by the site location (latitude and longitude) should match with that of the Hourly weather file. If you would like DesignBuilder to enforce a minimum distance then check this option.

Maximum allowed distance

If the above Check distance between site location and weather file option is checked then enter the maximum distance allowed between the location defined by the site latitude/longitude and the latitude/longitude set for the Hourly weather file here (in m or ft). The default setting is 200,000m i.e. 200km.

Using Custom versions of EnergyPlus

If you have compiled a special version of EnergyPlus you can use it to run simulations from within DesignBuilder by following the instructions below. Note that the custom version must be based on one of the versions supported by DesignBuilder and ideally the default version. The instructions are easiest if the version number of your custom compilation is the exactly the same as that of a version that is supported by DesignBuilder.

When the custom version has the same version number as a supported version

1. Recompile your new version of EnergyPlus into EXE form (not DLL)
2. Select the EXE option from the EnergyPlus program options corresponding to the custom version.
3. This downloads and installs the appropriate standard version of EnergyPlus from the DesignBuilder servers to the DesignBuilder EnergyPlus folder (if it hasn't already been downloaded).
4. Copy your custom EnergyPlus.exe (and Eplus+.idd if this has changed) to the DesignBuilder EnergyPlus folder overwriting the standard the files downloaded by DesignBuilder.
5. Test by running simulations from within DesignBuilder to ensure that your custom version is being run.

When the custom version has a new version number

1. Follow instructions 1-3 above selecting the standard version most similar to your custom version. This ensures that all standard files are installed ready to be overwritten with custom files.
2. Create a new version component from the EnergyPlus tab on the Program options dialog and enter the custom version on the dialog. See below.
   
   
   
   
3. Copy all of the EnergyPlus files which have changed typically EnergyPlus.exe and Energy+.idd to the DesignBuilder EnergyPlus folder.

4. Test by running simulations from within DesignBuilder to ensure that your custom version is being run.