# Interoperability between Building Information Modelling (BIM) and Building Energy Model (BEM)
## 3 Results and Discussion
### gbXML Import Results
#### 3.1.3. Residential Case in Open Studio  
As was mentioned above, Open Studio was also used to import the gbXMI file, and some steps were executed. First, it was verified that the imported data of the materials and the thermal zones were in line with those determined in Revit. Second, with respect  
\begin{table}
\begin{tabular}{p{14.2 pt} p{142.3 pt} p{142.3 pt} p{142.3 pt}} \hline \hline  & & & & \\ \hline \multirow{4}{*}{Dimensions} & 1. External dimensions. & Some walls were 4\% smaller and others were 2\% bigger than BIM & Walls 0.56\% smaller than BIM. \\ \cline{2-5}  & 1. Solution. & Modify the model in Design Builder. & Modify the model in Design Builder. \\ \cline{2-5}  & 2. Thermal zones area. & Some areas were 4\% smaller and other up to 10\% bigger than in the BIM. & Correct. \\ \cline{2-5}  & 2. Solution. & Modify the model in Design Builder. & - \\ \cline{2-5}  & 3. Thermal zones volume. & The volumes are at least 6\% bigger than in the BIM. & Correct. \\ \cline{2-5}  & 3. Solution. & Modify the model in Design Builder. & - \\ \hline \multirow{4}{*}{Geometry} & 4. Zones recognition. & Correct. Total of 13 zones. & Correct. Total of 21 zones. \\ \cline{2-5}  & 4. Solution. & - & - \\ \cline{2-5}  & 5. Building surfaces. & North walls and parts of the roof improperly constructed and presented some gaps. First floor is missing. Parts of the thermal envelope were recognized as shadow elements. & North walls and parts of the roof improperly constructed and presented some gaps. Ground floor is missing. Parts of the thermal envelope were recognized as shadow elements. & Apply parts of the thermal envelope were recognized as shadow elements. & Parts of the thermal envelope were recognized as shadow elements. \\ \cline{2-5}  & 5. Solution. & Modify the model in Design Builder. & Modify the model in Design Builder. \\ \hline \multirow{4}{*}{Materials} & 6. Building materials. & Correct. Two folders called “Imported” were created: One for constructive systems and another for materials.  
to the errors, it was not possible to measure the model facades in Open Studio. Then, the SketchUp 2017 software and the plug-in Open Studio for SketchUp were used to import the Open Studio file, in order to check whether the model dimensions were the same in the BIM and BEM software. However, the building dimensions were between 1% to 6% smaller and the thermal zones were 0.85% to 8% bigger than in Revit. These problems may have occurred because of the transferred data of the wall dimensions, if they were automatically recognized from external to external walls or from the middle of the internal walls. Unfortunately, this recognition cannot be controlled, either in the export of the gbXML or during its import into the BEM software.  
Finally, the geometry was not generated properly: As in Design Builder, the first floor and some parts of the wall of the north facade were recognized as shadow elements. This might have occurred because it is only necessary to model the building surfaces that enclose the thermal zones and the floor is modeled as a unique line in the BEM tool. Therefore, as the model was generated automatically, every space that was left over as a shadow element was recognized. In addition, some walls had gaps that did not appear in Revit (see Figure 7).