EnergyPlus is the whole building energy simulation engine used by the loadmodeling.tool. Several methods, routines, and features of the platform help to ensure models run successfully every time. When simulations do not, warnings are provided by the engine to help us modify the model and produce a successful run.

Viewing the warnings

When a model runs into issues, warnings direct from EnergyPlus will be reported to the EnergyPlus Warnings panel on the Results Page. Two types of warnings are reported: Severe and Fatal.

Severe warnings are displayed in orange and typically the warnings that taken together produce the fatal simulation. These will have details on the specific components in the model that need to be modified

Fatal warnings are displayed in bold orange and point toward the most important warnings that caused a simulation failure. Occasionally EnergyPlus can overcome some of the severe warnings, and this fatal warning denotes issues EnergyPlus was not able to overcome.

The full warning report from EnergyPlus can also be downloaded via the Export Warnings Report button. The exported file will be called eplusout.err and can be opened with any text editor such as Notepad or TextEdit.

Resolving Warnings

Here is a list of warnings and steps to resolve on the platform.

  • Heating Coil - Rated inlet water temperature must be greater than outlet water temperature

    • Review fluid temperature inputs of the Air System noted. For heating coils, the entering fluid temperature must be higher than the leaving fluid temperature. This is one of the many physics checks in the engine to ensure fundamental equations can resolve.

  • Cooling Coil - Rated inlet air temperature must be greater than the outlet air temperature

    • Review the entering and leaving air temperature inputs of the Air System noted. For cooling coils, the entering air temperature must be higher than the leaving air temperature. This is one of many physics checks in the engine to ensure fundamental equations can resolve.

  • Severe-DuelSetPointwithDeadBand: Effective heating set point higher than the effective cooling set point

    • Check the cooling and heating set points for the thermal zone/zones listed in the error. Any part of the cooling setpoint/setback should not be lower than any part of the heating setpoint/setback values. Once corrected, this error will be resolved.

  • Severe-Temperature (high) Out of Bounds for a zone or zones: Diagnostic Details: .Internal Heat Gain [] W/m2.

    • Check for the internal gains of the room templates for indicated thermal zone/zones in the error. There would be an additional template that needs to be deleted or an unreasonable value might have been entered in the internal zone prompts (people, lights, and equipment). Once fixed, the simulation will run successfully.

  • Severe- <root> [FenestrationSurface:Detailed] [Sub Surface xyz] - Missing required property 'construction_name'.

    • [Scenario 1] Check if there are any windows associated with Internal Walls. If the windows are inside a building, then you can delete the internal windows and re-run the simulation.

    • [Scenario 2] If by mistake, an exterior wall property is set to an interior wall and it has a window then this error will be seen as well. Upon properly setting the wall type to an exterior wall, this error will be resolved.

  • Severe- SetupEnclosuresAndAirBoundaries: Surface 'xyz' uses Construction:AirBoundary in a non-interzone surface

    • Air Walls should not be used as a part of the exterior envelope. The heat loss from that will result in the EnergyPlus simulation error noted above. Simply convert that air wall to an exterior wall within drawing.tool to resolve the error. Please re-export from the drawing.tool before rerunning the loadmodeling.tool simulation.

Also, EnergyPlus provides in-depth information on these messages in the official Tips and Tricks Using EnergyPlus guide. Chapter 14 includes a series of examples of warnings along with suggested resolutions.

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