For thermal models containing more than one thermal zone, it is essential to know the topological structure of the zones. This especially means that internal thermal boundaries and their relations to the correnponding thermal zones need to be identified.
Energy ADE 1.0 represent an internal thermal boundary by one object ThermalBoundary (with thermalBoundaryType interiorWall, intermediaryFloor, ...), being related with two objects ThermalZone. This sounds good, but in fact is incorrect. In reality, thermal boundaries are oriented surfaces bounding the volume of the different thermal zones. The normal convention is that the orientation of a thermal boundary- in the Energy ADE either represented by the attributes azimuth / inclination or by an explicit surface (attribute surfaceGeometry ) - points out of the zone volume. In consequence, an internal thermal boundary cannont be correctly represented by only one ThermalBoundary object.
In the process of transforming an Energy ADE 1.0 model into a specifc simulation model like EnergyPlus IFD-file, it might principally be possible to correct this unavoidably error and switch the surface orientation for one of the two adjacent zones, but this is very difficult to implement. Therefore, a new concept is proposed to specify the topological structure in multi-zone models:
Each ThermalBoundary object belongs to exactly one ThermalZone object. In consequence, internal thermal boundaries (and if necessary also internal thermal openings) are represented by two ThermalBoundary / ThermalOpening objects, refering each other by a relation isAdjacentTo of cardinality 0..1.