picking apart the Google SketchUp minimal file

Now that we've seen the basic content of Google SketchUp .inp file, let's pick it apart and see exactly what the plugin is giving us.



First, the stuff we knew we would need, based on a non-SketchUp minimal file:



VERSION,2.2.0;

This is an important cue to the program... We saw in my first post that the model is executed slightly differently depending on whether this is in the file or not. If it wasn't there, we might see strange problems when running the model in a different version of EnergyPlus. The program would try to run the model expecting it to be compatible with the version of the program being used -- this is often a bad assumption since the EnergyPlus developers are always refining the structure of the information in the file to make it suited to more situations.



BUILDING, Building, 0.0, CITY, 0.04, 0.4, FULLINTERIORANDEXTERIOR, 25;



On comparing the output from the Sketchup plugin to the default output created from the .idf editor, we see this:

• The default name of building for Sketchup is "Building", where it is "NONE" for the .idf editor.


• The orientation is specified by Sketchup as Model North=True North, which is the same as the default value implied by the .idf editor.


• The terrain specified by the Sketchup plugin is CITY, where the .idf editor defaults to Suburbs. This has an effect on the calculation of wind on the building exterior. Interesting that they are different.


• Both programs use 0.04 watts for the Loads Convergence Tolerance Value, which is also the same as the default.


• Also, both programs use 0.4 degrees C as the Temperature Convergence Tolerance Value, which is the same as the default.


• The Sketchup plugin specifies FULLINTERIORANDEXTERIOR for the solar distribution model, but the .idf editor uses FullExterior. The Sketchup setting provides for more accurate simulation, but the documentation states that there are some condititons that must be met to be able to use FULLINTERIORANDEXTERIOR, e.g. the space must be convex (every possible line through the space can intersect only two walls).


• Maximum number of warmup days is 25 in both files as well as the default.

SurfaceGeometry,UPPERLEFTCORNER, COUNTERCLOCKWISE, WORLD;



For the SurfaceGeometry object, we see the following:

• The surface starting position is UPPERLEFTCORNER in both programs. There is no default.


• The vertex entry order is COUNTERCLOCKWISE in both programs. again, no default.


• The Coordinate system is WORLD in the Google Sketchup plugin and relative in the .idf editor. This is important to note if you will be editing geometry in the .idf editor, since the origin will have a large effect on the coordinates to be specified.


• For the daylight reference point coordinate system, the Sketchup plugin leaves it blank (making it default to relative) while the .idf editor explicitly sets it to be relative. I'm wondering if it is wise to position the daylight reference point with relative coordinates when the surface itself is specified with world coordinates... I guess the important thing is to be aware of this, since it could affect daylight sensor performance.

RUNPERIOD,1, !- Begin Month1, !- Begin Day Of Month12, !- End Month31, !- End Day Of MonthSUNDAY; !- Day Of Week For Start Day

RunPeriod, 1, 1, 12, 31, UseWeatherFile, Yes, Yes, No, Yes, Yes, 1;

This post was not completed, and sat waiting to be completed for several months. I've posted it as is, in case it might be helpful to others in the future.