Input Output Reference — EnergyPlus 22.1

Input Output Reference

EnergyPlus produces several output files as shown in the section on “Running EnergyPlus”. This section will discuss the data contained in the “standard” output files (eplusout.eso, eplusout.mtr). They, too, have data dictionaries but unlike the input files, the output data dictionary is contained within the output file. Thus, the basic structure of the standard output file is:

Data Dictionary Information
End of Data Dictionary
Data
...
Data
End of Data

As with the IDF structure, there are rules associated with the interpretation of the standard output data dictionary. These rules are summarized as follows:

• The first item on each line is an integer which represents the “report code”. This “report code” will be listed in the data section where it will also be the first item on each line, identifying the data. Only 2 lines in the output file will not have an integer as the first item (“End of Data Dictionary” and “End of Data” lines).

• The second item on each line is also an integer. This integer corresponds to the number of items left on the dictionary line. Each string consists of a variable name and units in square brackets. Square brackets are required for all strings. If there are no units associated with a particular variable, then there are no characters between the brackets.

Six standard items appear at the start of every EnergyPlus Standard Output File Data Dictionary:

Program Version,EnergyPlus <version number indicated>
1,5,Environment Title[],Latitude[degrees],Longitude[degrees],Time Zone[],Elevation[m]
2,6,Day of Simulation[],Month[],Day of Month[],DST Indicator[1 = yes 0 = no],Hour[],StartMinute[],EndMinute[],DayType
3,3,Cumulative Day of Simulation[],Month[],Day of Month[],DST Indicator[1 = yes 0 = no],DayType  ! When Daily Output variables Requested
4,2,Cumulative Days of Simulation[],Month[]  ! When Monthly Output variables Requested
5,1,Cumulative Days of Simulation[] ! When Run Period Output variables Requested
• Item 0 is the program version statement.

• Item 1 is produced at the beginning of each new “environment” (design day, run period).

• Item 2 is produced prior to any variable reported at the timestep or hourly intervals. Hourly intervals will be shown with a start minute of 0.0 and an end minute of 60.0. Timestep intervals will show the appropriate start and end minutes.

• Item 3 is produced prior to any variable reported at the daily interval.

• Item 4 is produced prior to any variable reported at the monthly interval.

• Item 5 is produced prior to any variable reported at the end of the “environment”.

Following these five standard lines will be the variables requested for reporting from the input file (ref. Output:Variable object). For example:

6,1,Environment,Site Outdoor Air Drybulb Temperature [C] !Hourly
40,1,ZONE ONE,Zone Total Internal Latent Gain Energy [J] !Hourly
68,1,ZONE ONE,Zone Mean Radiant Temperature [C] !Hourly
69,1,ZONE ONE,Zone Mean Air Temperature [C] !Hourly
70,1,ZONE ONE,Zone Air Heat Balance Surface Convection Rate [W] !Hourly
71,1,ZONE ONE,Zone Air Heat Balance Air Energy Storage Rate [W] !Hourly

This example illustrates the non-consecutive nature of the “report codes”. Internally, EnergyPlus counts each variable that could be reported. This is the assigned “report code”. However, the user may not request each possible variable for reporting. Note that, currently, the requested reporting frequency is shown as a comment (!) line in the standard output file.

The data is produced when the actual simulation is performed (after the warmup days unless the Output:Diagnostics requesting ReportDuringWarmup is used). Data output is simpler in format than the data dictionary lines. From the dictionary above:

1,DENVER STAPLETON INTL ARPT ANN HTG 99% CONDNS DB,  39.74,-105.18,  -7.00,1829.00
2,1,12,21, 0, 1, 0.00,60.00,WinterDesignDay
6,-16.
40,0.0
68,-19.8183039170649
69,-19.8220899203323
70,-3.175272922406513E-002
71,-3.181520440307718E-002

This output file can be easily turned into a form that is read into commonly used spreadsheet programs where it can be further analyzed, graphed, etc.

More details including graphs are shown in the Output Details and Examples Document under the file eplusout.eso.