How to Review Model Geometry

drawing.tool, geometry, loadmodeling.tool, troubleshooting

Patrick Chopson avatar
Written by Patrick Chopson
Updated over a week ago

Occasionally, simulations will encounter errors without the EnergyPlus Troubleshooting panel. This indicates some project geometry conditions are responsible. Example project geometry conditions are listed in this article along with the solution for them.

Check 1: Room or group of rooms are completely enclosed by other room

How to identify:

This condition is typically found with corridors where a room or set of rooms is enclosed by another room. This can error out the simulation because EnergyPlus is unable to set boundary conditions properly.

Steps to correct:

Simply, break the corridor or encircling room so that no single room encloses others. Here is an example using air-walls.

Check 2: Tiny walls or endpoints that are not part of any room

Endpoints without walls can cause the simulation to fail by creating slivers and surfaces that only have two vertexes.

How to identify:

  • To find these types of endpoints turn on the Endpoint Snap

  • Next, turn on the wall mode to display all the endpoints within the project

  • Endpoints that are not associated with a wall will need to be deleted

Steps to correct:

These endpoints can be removed by extending the wall they are trying to create and then deleting them. In order to select these endpoints follow these steps:

  • Turn off the Visibility of Floors

  • Use Shift drag+click to select the area around the extra endpoint

  • Next, select and drag the problem endpoint to create a full wall

  • Delete this wall

Check 3: Internal walls not defining a Room

How to identify:

Wing walls or disconnected walls can cause issues in OpenStudio related to the vertex. Importantly they will have essentially no impact on the loads and for best success should be removed.

Steps to correct:

  • As noted, these walls be removed without impacting the load results

  • Alternatively, if a room is meant to be defined, adding the missing surfaces will also correct the potential issue

Check 4: Look out for overlapping windows

How to identify:

Tap on the '3D' button at the top bar in the drawing.tool. Here's a great article to refer to understand the drawing.tool interface.

User-uploaded Image
User-uploaded Image

Steps to correct:

  • Delete the overlapping windows by simply selecting the window and clicking on the 'delete' keyboard button.

  • Alternatively, the orange windows can be moved until they do not overlap with other windows.

Check 5: Sliver Rooms

How to identify:

Sliver rooms or very thin void rooms cause issues within the EnergyPlus engine due to vertex oddities. These also can impact the load incorrectly as loads that are per area may be over-estimated.

Attached below is an example of a sliver room

Steps to correct:

  • A single wall should separate the two rooms. The corrected sample is provided below

  • This simplified the model to optimize the run time of the simulation.

Check 6: Extra Vertex in Walls

How to identify:

Extra nodes or vertex can be created during an import or while drawing walls within the tool. When drawing the walls and deleting we can sometimes see that a leftover

Steps to correct:

  • Remove the extra vertex to make it a single wall by single-clicking the endpoint icon (blue circle)

Important Note: This case will not always fail, however when it does the warning will be related to vertex mismatch.

Related Articles:

Did this answer your question?