How to Generate and View Extra EnergyPlus Outputs

EnergyPlus provides literally thousands of different output report types and DesignBuilder allows you to access the most useful of these through the main Simulation results screen. Sometimes however it can be useful to access some the other reports and this help topic explains how to go about generating and viewing any EnergyPlus outputs. The process is illustrated through a step by step tutorial at the end.

Requesting the Extra Outputs

The first step is to request the extra outputs. Ultimately, this involves adding extra lines of IDF script to the EnergyPlus IDF input file and there are 2 ways to do this:

• The easiest way is by using the Add Output Scripting dialog. This approach requires a licence for the Scripting module.
• Alternatively if you don’t have access to the Scripting module you can use the more basic Include IDF Data option.

These 2 methods are described below in more detail.

Adding Extra Outputs Using the Scripting tools

If you have a licence for the Scripting module then the method below is the easiest way to add extra outputs and ensures that the extra outputs will be generated even if the model is sent to a colleague to simulate.

1. Click on the Scripts toolbar icon to open the Script Manager dialog and then Enable scripts.
2. Add a new EMS script, give it a name, enable the program and click on the blank script page.
3. Click on the Add Output link on the Info panel and, if asked about re-generating the list of available outputs, actuators and sensors, click Yes.
4. There will be a pause while EnergyPlus generates the list of available reports customised for the current model, after which the Add Output dialog is displayed. Here you can enter the object name (use * for all), select the interval and then select the output reports you need by double-clicking on the appropriate items in the list. Note that if your model is not in a state that allows simulations to run at this point, or if it is a large model and you don't want to wait for EnergyPlus to generate the RDD file, you can access the list of available outputs from a RDD file that was manually generated in a previous simulation and copy/paste report names to the script manually. The manual process is outlined in the tip in the Adding Extra Output Reports using “Include IDF Data” section below.
5. Once the required list of outputs has been set up press OK to confirm the settings and to create the script.
6. Press OK on the EMS Script dialog and the selected outputs will be included in the .eso results file after any subsequent simulations.

Note: You can find detailed descriptions on all of the available EnergyPlus outputs from the Input Output Reference document.

Adding Extra Output Reports using “Include IDF Data”

If you don’t have access to the Scripting module you can still request extra output reports using the Include IDF Data Calculation option. In this case you will need to write the IDF script manually, save it to an IDF file and reference that from the Include IDF Data Advanced setting on the Simulation Calculation Options dialog.

In more detail:

1. Generate the full list of EnergyPlus outputs available for your simulation by selecting the RDD/EDD file output option and running a test simulation. Note that if you used the Simulation Manager to run the simulation you must load results to DesignBuilder to be able to access the RDD file in the EnergyPlus folder.

2. After the simulation has completed, access the RDD file from the EnergyPlus Folder and open it.

3. Search within the RDD file for the required variable names and copy them. If you are not sure exactly what a EnergyPlus variable name means, you can copy it and search for it within the relevant version of the EnergyPlus InputOutput manual.

4. Save a text file using the idf extension with a list of all the new required variable names using the required IDF syntax. The IDF file must be saved in the EnergyPlus Folder.

5. Now select your custom IDF file from the Simulation Calculation Options dialog on the Options Tab, under the Advanced header. When you run your next simulation your custom IDF will be included in the input data provided to EnergyPlus.

6. After the simulation has completed, view the results using Results Viewer.

7. Use Results Viewer's filter function to find the custom results of interest.

IDF Report Variable Format

 

The format used by EnergyPlus to define the "reports" (output data) required is described below.

 

A single "report" can be thought of as a single set of output data or alternatively as a line of data on a graph and is defined using a single line of text using this syntax:

 

Output:Variable, <Object name>, <Report Name>, <Interval>

 

• Output:Variable is an IDF keyword which indicates that what follows is a request for output data.
• <Object name> is the name of the object for which data is required, e.g. the zone or the HVAC component name. In some cases it is possible to enter "*" to indicate that the data is required for all relevant objects (e.g. all zones).
• <Report Name> is the name of the report (output data) required. Thousands of reports are available in all and you should refer to the EnergyPlus help file for details on what is available.
• <Interval> should be one of the following keywords:
  

   

  • Monthly
  • Daily
  • Hourly
  • Timestep - corresponds to the sub-hourly interval in DesignBuilder terminology.
  • Detailed - a special interval provided by EnergyPlus where detail down to the level of the HVAC timesteps can be provided. the actual intervals reported will often vary during the simulation, but it can at times provide useful debugging information.

 

For example to generate a new hourly data set for the "Time Heating Setpoint Not Met While Occupied" report for the zone having IDF name "Block1:Zone1" add this line of text to the IDF file:

 

Output:Variable, Block1:Zone1, Time Heating Setpoint Not Met While Occupied, hourly;

 

To generate sub-hourly data on the activity of the ideal loads economiser for all zones use:

 

Output:Variable, *, Ideal Loads Time Economizer Active, timestep;

 

Note the use of the "*" character to mean all objects and the semi-colon at the end of the line. For further clarification on how to specify requests for EnergyPlus outputs you can refer to the Output:Variable data provided by DesignBuilder in previously generated IDF files.

 

The above is just one way of obtaining outputs. Once familiar with EnergyPlus reports you can be creative with use of additional IDF to request further outputs.

Viewing Extra Output Reports

Regardless of the way you used to generate the extra outputs, the method used to view them is the same, namely through DesignBuilder’s standalone Results Viewer application. If you are using the Simulation Manager you can do this by selecting the simulation(s) of interest and clicking on the View results in DesignBuilder Results Viewer toolbar icon. Otherwise you can use the View EnergyPlus results toolbar icon on the Simulation screen to open the most recently simulated results into the Results Viewer. More details on how to load eso results files into the Results Viewer can be found in the Results Viewer help.

Tutorial - Viewing Direct and Diffuse Solar Radiation Incident on a PV Panel

This tutorial provides details on how to view extra outputs for PV panels that are not provided on the standard Simulation results screen. In particular it shows how to generate and view a breakdown of the direct and diffuse solar radiation incident on a PV Panel.

The tutorial assumes that you have access to the Scripting module. If you do not then you can achieve the same results through the Include IDF Data, though in this case the process is a little less convenient.

The screenshot below shows the simple model to be used to illustrate the method in this tutorial. It consists of a 20x10m rectangular block with a single zone and a 5x2m South-facing PV solar collector panel sitting on the roof at an angle of 30° from horizontal. The building is located in London/Gatwick UK.

Add Extra Outputs

1. Start by clicking on the Scripts toolbar icon to open the Script Manager dialog.
2. Check the Enable scripts checkbox and click on the Script selector option to open the list of existing scripts in the Info panel browse list on the right.
3. Click on the Add new item Info panel toolbar icon.
4. On the Edit Script dialog that pops up provide a name for the script, such as "Extra Solar Outputs" and check the Enable program checkbox to ensure that the script will be executed at Simulation run time.
5. Click on the Add Output link in the Info panel .
6. At this point you will see a message to say that no RDD data is stored in the model and would you like to regenerate the list. Answer Yes and there will be a short pause while EnergyPlus generates the list, after which the Add Output dialog is displayed.
7. Enter the object name. You could enter "*" to select all surfaces in the model, or to be more efficient in this case it would be better to enter "Solar collector 1", which is the IDF name of the surface used to represent the PV panel in the model.
8. Select 3-Hourly as the interval.
9. Reading the relevant sections of the EnergyPlus Input Output Reference guide shows that the required outputs are:

   • Surface Outside Face Incident Sky Diffuse Solar Radiation Rate per Area

   • Surface Outside Face Incident Beam Solar Radiation Rate per Area and
10. Add these 2 reports to the list of selected outputs on the Add Output dialog by double-clicking on the appropriate items in the Info panel list. At this stage the Add Outputs dialog should look something like the screenshot below. When you have selected the required outputs press OK to confirm and add the requested script to the main EMS scripting window.
    
11. The script should look like this:
    Output:Variable, Solar Collector 1, Surface Outside Face Incident Beam Solar Radiation Rate per Area, Hourly;
    Output:Variable, Solar Collector 1, Surface Outside Face Incident Sky Diffuse Solar Radiation Rate per Area, Hourly;
12. Press OK to confirm that and then also press OK on the Script Manager dialog to return to the main DesignBuilder window.
13. Run an annual simulation using the Simulation Manager by checking the Use Simulation Manager checkbox on the Simulation Manager tab of the Simulation Calculation Options dialog.
    

If all has gone according to plan you will now have generated the extra outputs.

View the Results

1. If you have not already done so, download and install the latest version of the Results Viewer from the DesignBuilder website.
2. If the Simulation Manager dialog isn't already open from when you ran the simulation, click on the Simulation Manager toolbar icon to open it.
3. Select the simulation you have just run and click on the View results in DesignBuilder Results Viewer toolbar icon as shown in the screenshot below.
   
   
4. In Results Viewer, click on the Hourly tab, select both the 2 extra outputs "Surface Outside Face Incident Beam Solar Radiation Rate per Area" and "Surface Outside Face Incident Sky Diffuse Solar Radiation Rate per Area" (hold the <Ctrl> key down and click with the mouse to select more than 1 report).
   
5. Click on the Add selected variables to new graph toolbar icon .
6. Results similar to those below should be displayed.
   
   Using the zoom tool to check hourly values of the direct and diffuse solar incident radiation on the panel for a summer week: