# The surface has an edge that is either not an edge on another surface or is an edge on three or more surfaces

Can anyone help me understand why I'm encountering these warnings?

I defined two zones, one within the another one.

```
Program Version,EnergyPlus, Version 9.2.0-921312fa1d, YMD=2024.02.04 20:05,
** Warning ** CalculateZoneVolume: The Zone="OUTER ZONE" is not fully enclosed. To be fully enclosed, each edge of a surface must also be an edge on one other surface.
** ~~~ ** The zone volume was calculated using the opposite wall area times the distance between them method
** ~~~ ** The surface "iz-INNERZONE WALL 1" has an edge that is either not an edge on another surface or is an edge on three or more surfaces:
** ~~~ ** Vertex start { 1.0000, 1.0000, 0.0000}
** ~~~ ** Vertex end { 1.0000, 4.5000, 0.0000}
** ~~~ ** The surface "iz-INNERZONE WALL 2" has an edge that is either not an edge on another surface or is an edge on three or more surfaces:
** ~~~ ** Vertex start { 5.0000, 1.0000, 0.0000}
** ~~~ ** Vertex end { 1.0000, 1.0000, 0.0000}
** ~~~ ** The surface "iz-INNERZONE WALL 3" has an edge that is either not an edge on another surface or is an edge on three or more surfaces:
** ~~~ ** Vertex start { 5.0000, 4.5000, 0.0000}
** ~~~ ** Vertex end { 5.0000, 1.0000, 0.0000}
** ~~~ ** The surface "iz-INNERZONE WALL 4" has an edge that is either not an edge on another surface or is an edge on three or more surfaces:
** ~~~ ** Vertex start { 1.0000, 4.5000, 0.0000}
** ~~~ ** Vertex end { 5.0000, 4.5000, 0.0000}
```

See https://unmethours.com/question/33919...