Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page

# EnergyPlus output of heat load

I have 3 different type of buildings simulation. And I have the results in eso file.

I am looking for the heat load (the heat demand/heat need to maintain the set point temperature, the heat gain from solar, people etc are not taking into account)at each time step. I used DesignBuilder, I noticed that they could do DesignDay heating calculation, but this is giving me one number of zone sensible heating (kW).

I am not sure which OUTPUT: VARIABLES OUTPUT:METERS I should looking for. I used EnergyPlus v8.3, since v8.1 they changed some of the output names, such as 'zone/sys heating rate' to 'zone air system sensible heating rate'. It caused me lot of time to figure out. Is there any doc to explain all the output variables and meters? When I type some of the output variables or meters name in google try to figure out its meaning, however, it is not a easy thing. If you guys have some tips please let me know.

What I found here is the 'Heating:EnergyTransfer' = 'Energy Transfer: Building' = total 'zone air system sensible heating rate', and from the definition of the zone air system sensible heating rate is the heating delivered by HVAC system to the zone. From my understanding, this heating rate is the heat demand minus the heat gain from solar, people etc. Please correct me if I am wrong here.

And there is 'Energy Transfer:facility', from my understanding, Facility meters contain all the energy of a fuel type. Building meters contain the sum of each zone’s energy. HVAC meters contain the energy from the air and zone HVAC system components. Plant meters contain the energy from the plant equipment. Facility = building + HVAC + Plant + exterior

I have attached the results. The red line is the energy transfer:facility, the blue line is the energy transfer:building.

Not sure which specific variables or meters I should use to represent the heat load at each time step, I believe there should be, coz the fundamental method of EnergyPlus 'heat balance' is based on the calculated heat load.

And additionally, I found out one ppt explain the output file format of EnergyPlus, and it shows that there is one CSV output file contains all data in the eso file, does anyone know how I could get this CSV file please? I want to use some of the output variables in timestep frequency (not monthly or hourly) to plot the results, such as electricity:facility, electricity generated etc.

edit retag close merge delete

@nancynanxiaodan, a comment about your slides of all things. The term is "stream of consciousness" (awareness). "Conscience" (inner voice of morality) is a different thing. :)

( 2015-12-09 06:48:22 -0600 )edit

( 2015-12-09 17:38:38 -0600 )edit

Sort by » oldest newest most voted

In general, any Output:Variable and Output:Meter objects available to use depend upon what objects are in your E+ model. If you check the X.rdd file after a simulation, you'll see the current list of available VARIABLES that can be reported in the X.csv file ( "X" is the same name as your IDF file, and all output files are all generated in the same directory as your IDF file). Likewise, you can check the X.mdd file after a simulation, you'll see the current list of available METERS that can be reported in the X.mtr file. There are generally more options for variables than meters. The best doc to explain all of the meter and variable options is the Input Output Reference. Each object has separate sections explaining the input fields as well as the outputs.

The Zone Air System Sensible Heating Rate output variable you mention is the energy actually supplied by the system to a zone. Ideally this is equal or close to the heat energy the zone demands, but maybe the HVAC system is CAV or has other operational settings that make it difficult to supply varied amounts of heating energy to exactly match heating demand.

You have two options to report heating demand in zones:

• Check the zone sizing CSV output file, which is generated whenever you have a Sizing:Zone object in your E+ model. For each zone, this CSV output file contains four columns: heating design load and heating design flow rate during heating design day, and cooling design load and cooling design flow during cooling design day. Values are reported hourly. The file is named XZsz.csv and will contain one day of data.
• The two output variables you seem to be interested in are Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate (output variable from the ZoneControl:Thermostat object) for zone-level heating demand and Plant Supply Side Heating Demand Rate (output variable from the PlantLoop object) for plant-level heating demand. Again, these variables will be added to the X.csv file, which contains data for the length of your simulation. You can have these output at whatever time interval you desire (hourly, simulation timestep, daily, etc.).

I hope this helps!

more