For best results with Energy Evaluation, follow these conventions of building energy modeling in ArchiCAD:
•Use the Mesh tool to model the building site’s grade level, especially if it is uneven.
•Do not use multiple separate parallel walls (or slabs or roofs) to model composite structures. If such constructions exist in the building model, make sure that only one of the parallel structures is visible in the energy model, and that the adjacent Internal Space Zones touch that structure.
•Use fills consistently within your project: a particular fill should always indicate the same single building material or composite.
See Direct BIM to BEM for more details on modeling guidelines.