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Unused Non-Parent Objects

asked 2017-01-13 05:42:47 -0500

updated 2017-01-19 06:37:58 -0500

I'm casting about, trying to figure out why:

  • zones are not meeting their setpoint
  • there is apparently no recognized value for the zone node's "System Node Setpoint Temperature" for output:variable (it displays as a large negative value), despite using a normal combination of SetpointManager:SingleZone:Reheat and ZoneControl:Thermostat for my single zone air loops

As I look for clues, I see in the .SVG file that all of the SetpointManager:SingleZone:Reheat objects are identified as "Unused Non-Parent Objects". I'm fairly sure that may have displayed in the past, but I never had good reason to dig into it before. A search of the IO Ref and Engineering Ref does not result in anything...

So, may I please have some ideas about:

  1. what may cause the zone node to have no associated setpoint value?
  2. whether an "unused non-parent object" is a problem?

p.s., In case you're interested and able to take a look, the IDF is here

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Regarding the second question I ran in to the same problem with humidity set point manager, so I used “DOASDXCOIL_wADPBFMethod.idf” example file that comes with EnergyPlus installation. The simulation showed 0 Warnings 0 Severe Errors, but the SVG file showed some Unused Non-Parent Objects. I added “Output:Diagnostics, DisplayUnusedObjects” to the outputs, and got the same results. What I concluded from that and from looking at the xml construction of the SVG file, is the “Unused Non-Parent Objects” refers to objects in the model, but are not shown on the SVG diagram

Saif gravatar image Saif  ( 2019-03-16 12:19:07 -0500 )edit

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answered 2020-12-28 12:45:17 -0500

  1. I would recommend adding the "Zone Thermostat Heating Setpoint Temperature" and "Zone Thermostat Cooling Setpoint Temperature" output variables to confirm that thermostats are defined correctly. The setpoint manager may be controlling the temperature from the outlet node after the reheat coil or terminal, which is technically the inlet node to the zone -- not the air node for the zone itself.

  2. No, the "Unused Non-Parent Object" message in the SVG file shouldn't cause you issues in terms of simulation results or accuracy. @jason_glazer should confirm this since he wrote the HVAC-Diagram auxiliary program that converts the BND file (branches and node connections) into the SVG file that shows HVAC diagrams. The HVAC-Diagram auxiliary program has a preset list of objects that it looks for in order to build the HVAC diagrams (see the table in this link). If an object in your IDF isn't part of that list, then it shows as an "Unused Non-Parent Object" at the bottom of the SVG file (source code for where that message is generated). This message has no impact on the EnergyPlus simulation itself -- just the SVG diagram.

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Asked: 2017-01-13 05:42:47 -0500

Seen: 155 times

Last updated: Dec 28 '20