AdjacentSpaceId

ID for a space that is bounded by this surface. First AdjacentSpaceId entered will determine how the referenced construction layers are ordered with the first construction layer being in contact with the outside or 2nd space listed and the last layer in contact with the first space listed. The outward normal of the surface, as defined by the right hand rule of the coordinates in the planar geometry element, is always pointing away from the first AdjacentSpaceID listed.

With interior horizontal surfaces, this attribute can distinguish between ceiling and floor surfaces to avoid double-counting of floor areas, etc. If not present, the surface type can be assumed based on the description of the surface type enums. When the surfaceTypeEnum is provided and the surface attributes (i.e. adjacency, tilt angle) do not match the enumeration's description, the enumeration should have precedence.