Knowledgebase: Output
Reporting options in EnergyPlus
Posted by Richard Raustad, Last modified by Richard Raustad on 18 June 2009 01:15 PM
Question:

I´m trying to size a boiler with a fan coil system. I would like to know the power of the boiler. Where can i find this data? Which output should i use in order to get it?

Answer:

There are many report variables in EnergyPlus. The ones available for a specific simulaiton are listed in the report data dictionary (rdd) file. These report variables may be generated automatically if the following is included in the input file.

Output:VariableDictionary,
Regular; !- Key Field

When the object above is included in an input file, the rdd file is available for review AFTER the simulation has completed. If this object is not inculded in the input file, the user may still use report variables, but must select them based on the objects inlcuded in the simulation. The Input Output Reference document describes all report variables available for each EnergyPlus object.

There are several choices on format with this object. You can specify "Regular" as the key field and the rdd will show all report variables along with the variable description as shown below.

HVAC,Average,Boiler Heating Output Rate [W]
HVAC,Sum,Boiler Heating Output Energy [J]
HVAC,Average,Boiler Gas Consumption Rate [W]
HVAC,Sum,Boiler Gas Consumption [J]
HVAC,Average,Boiler Water Inlet Temp [C]
HVAC,Average,Boiler Water Outlet Temp [C]
HVAC,Average,Boiler Water Mass Flow Rate [kg/s]
HVAC,Average,Boiler Parasitic Electric Consumption Rate [W]
HVAC,Sum,Boiler Parasitic Electric Consumption [J]
HVAC,Average,Boiler Part-Load Ratio []

As an alternative, the key field "IDF" may also be used.

Output:VariableDictionary,
IDF; !- Key Field

With this option the rdd will format the report variable so that they may be copied directly into the input file using a text editor.

Output:Variable,*,Boiler Heating Output Rate,hourly; !- HVAC Average [W]
Output:Variable,*,Boiler Heating Output Energy,hourly; !- HVAC Sum [J]
Output:Variable,*,Boiler Gas Consumption Rate,hourly; !- HVAC Average [W]
Output:Variable,*,Boiler Gas Consumption,hourly; !- HVAC Sum [J]
Output:Variable,*,Boiler Water Inlet Temp,hourly; !- HVAC Average [C]
Output:Variable,*,Boiler Water Outlet Temp,hourly; !- HVAC Average [C]
Output:Variable,*,Boiler Water Mass Flow Rate,hourly; !- HVAC Average [kg/s]
Output:Variable,*,Boiler Parasitic Electric Consumption Rate,hourly; !- HVAC Average [W]
Output:Variable,*,Boiler Parasitic Electric Consumption,hourly; !- HVAC Sum [J]
Output:Variable,*,Boiler Part-Load Ratio,hourly; !- HVAC Average []

The expanded version of the output variable object is shown below.

Output:Variable,
*, !- Key Value
Boiler Heating Output Rate, !- Variable Name
hourly, !- Reporting Frequency
MyReportVarSchedule; !- Schedule Name

Schedule:Compact,
MyReportVarSchedule, !- Name
On/Off, !- Schedule Type Limits Name
Through: 1/20, !- Field 1
For: AllDays, !- Field 2
Until: 24:00, 0.0, !- Field 4
Through: 12/31, !- Field 5
For: AllDays, !- Field 6
Until: 24:00, 1.0; !- Field 8

ScheduleTypeLimits,
On/Off, !- Name
0:1, !- Range
DISCRETE; !- Numeric Type

This allows several options for reporting. First the key value may be an asteric (*) where all report variables of this type are reported (for all boilers). Or the key value could be specified such that only a single output will be generated. For example if the key value was specified as "My Boiler" and a boiler object with the name My Boiler was included in the input, only the Boiler Heating Output Rate for this specific boiler will be in the output file (.csv). The reporting output for all other boilers in the simulation will not be included in the csv file.

The reporting frequency is also another option and may be one of several choices (e.g., Timestep, Hourly, Daily, Monthly, RunPeriod, Environment, Annual or Detailed).

The detailed reporting frequency reports the data for every simulation time step (HVAC variable time steps). This choice is useful for detailed troubleshooting and reporting.
The other choices average or sum the data over the selected interval. Timestep refers to the zone Timestep/Number of Timesteps in hour value and reports the data at regular intervals. Using RunPeriod, Environment, or Annual will have the same affect on the reporting frequency and refer to the length of the simulaiton as specified in the RunPeriod object.

Timestep,
4; !- Number of Timesteps per Hour

RunPeriod,
1, !- Begin Month
1, !- Begin Day of Month
12, !- End Month
31, !- End Day of Month
Tuesday, !- Day of Week for Start Day
Yes, !- Use Weather File Holidays and Special Days
Yes, !- Use Weather File Daylight Saving Period
No, !- Apply Weekend Holiday Rule
Yes, !- Use Weather File Rain Indicators
Yes; !- Use Weather File Snow Indicators

A schedule may also be used to turn on or off report variable at selected intervals.

Table reports and meters are also available as reporting options. See the Input Output and Engineering Reference manuals for further details.
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