# What output variable will show a difference between a model with convex vs. non-convex surfaces

I have a model with some non-convex surfaces and I receive this warning

```
** Warning ** DetermineShadowingCombinations: There are 12 surfaces which are receiving surfaces and are non-convex.
** ~~~ ** ...Shadowing values may be inaccurate. Check .shd report file for more surface shading details
** ~~~ ** ...Add Output:Diagnostics,DisplayExtraWarnings; to see individual warnings for each surface.
```

I have changed the non-convex surfaces to convex surfaces in the model. What output from Energyplus will show a difference in the simulation, if any, between the model with non-convex surfaces and the model with all surfaces converted to convex shapes?

I want to use the model with the non-convex surfaces since it runs faster, but not at the expense of incorrect results, so I want to compare the output of the two simulations.

UPDATE:

I split up 2 of the 12 non-convex surfaces into multiple convex surfaces. One surface I split was interior to the building and it added about 0.02 GJ to the energy usage. The other surface I split was a flat roof which, strangely, decreased the energy used by about 0.7 GJ. I thought changing the roof would have no effect because it is a horizontal roof that is not being shaded.

@Julien Marrec I am unaware of which solar distribution I am using. The field is blank. What is the default?