1. A cloud-based platform for IFC file enrichment with
second-level space boundary topology
July 7th, 2017
Georgios N. Lilis1, Kyriakos Katsigarakis1, Georgios Giannakis1
and Dimitrios Rovas1,2
(1Technical University of Crete, Chania, Greece;
2 University College London, London, United Kingdom);
Lean & Computing in Construction Congress 1

2. OUTLINE OptEEmAL project
Building Information Model to Building Energy Performance Simulation transformation
Platform
Concept
Software Architecture
Design Errors
Examples
Achievements
Features
Conclusions
MCDA: Multi-Criteria Decision Analysis 2 2

3. OPTEEMAL
Cloud-based platform for district retrofitting
implementing a 3-steps process:
Diagnosis (using input data) and formulation of scenarios.
Evaluation and optimization.
Best scenario selection and data exportation to stakeholders.
IFC 1
IFC 3
IFC 2 3

4. BIM – BEPS Building data in IFC STEP files (IFC4, DTV).
For evaluation of district retrofitting scenarios a fast and reliable method is required to use IFC data for setting up of building energy performance simulation inputs such as EnergyPlus (idf files).
Two major geometric requirements:
Geometric content of the IFC file should be “error free.”
The IFC geometric content should include 2nd level space boundaries[1].
2nd level space boundaries: Surfaces through which thermal energy flows either among building spaces or among a space and its environment (air/ground).
IFC 1
IFC 3
IFC 2
[1] Bazjanac, V. (2010). Space boundary requirements for modeling of building geometry for energy and other performance simulation. 27th CIB W78. Cairo 4

5. PLATFORM - CONCEPT
2nd level space boundary information is often wrong or missing. 5

6. PLATFORM - CONCEPT Input Enhanced IFC +
An online web-platform has been developed (accessible at which enriches IFC geometry with the 2nd-level space boundary information.
The enriched IFC files contain required geometric information required in building energy performance simulation (BEPS) tools.
Enhanced
IFC
Input +
Illustration of the platform’s main functionality. 6

7. PLATFORM – SOFTWARE ARCHITECTURE
Three operational stages:
IFC data extraction and xml string formation. The input IFC file is deserialized and the required geometric content is extracted (geometric representation of architectural elements: walls, slabs,…).
CBIP algorithm execution. This information is used as input to the CBIP algorithm[1] which produces the 2nd level space boundary topology.
IFC data enrichment. The surfaces of the 2nd level space boundary topology are used to enhance the input IFC data and the final IFC file is serialized with these data.
Three docker images are used hosted on dedicated servers (one for every operational stage) and multiple instances are activated.
[1] Lilis, G.N., Giannakis. G.I., Rovas D. (2017). Automatic generation of second-level space boundary topology from IFC geometry inputs. Automation in Construction, 76, 7

8. PLATFORM – SOFTWARE ARCHITECTURE
The user uploads the IFC file in a web-based User Interface.
Asynchronous communication between the different platform components is established using an Enterprise Service Bus architecture.
For every uploaded IFC file, a process stream is initiated with specific id tag #... .
Both original and enhanced IFC files can be downloaded.
Appropriate info button provides information about the process execution and, if detected, design errors on the input file.
Yellow process ends design errors exist in original IFC.
Green process ends no design errors exist in original IFC.
Red process does not end original IFC is not according to schema. 8

9. PLATFORM – DESIGN ERRORS
A yellow progress bar appears when design errors[1] exist in the original IFC file. The accuracy of the space boundaries in the enhanced IFC file cannot be guaranteed.
Space definition errors (error code 1001) One or more internal building space volumes is not surrounded by other building constructions (A) or a clash exists between a building space and a neighbor building element (B).
Site definition errors (error code 1002) Either the building site is not defined geometrically in the original IFC file (A), or the site surfaces are not attached other building elements (B). In such cases the surfaces of the building’s ground boundary conditions cannot be generated in the BEPS model.
[1] Lilis, G.N., Giannakis. G.I., Rovas D. (2017). Detection and semi-automatic correction of geometric inaccuracies in IFC files. Proc. of Building Simulation IBPSA conference 2015 Hyderabad, India, pp 9

10. PLATFORM – EXAMPLES
Simple case: IFC file of a two story demo building (<2sec time).
# SBs = 93 (Walls: 34, Plates: 32, Slabs: 21, Doors: 4, Windows: 2)
Results of space boundaries (Solibri Model Viewer). 1 2 1 2 1 2 3 3 3 3 3 10

11. PLATFORM – EXAMPLES
Complex case: TURINA torre OptEEmAL demo site building (11-story) (~2min 22sec time).
# SBs = 3798 (Walls: 2052, Slabs: 820, Doors: 653, Windows: 196, Openings: 45, Air: 32).
Results of space boundaries of basement (Solibri Model Viewer). 11

12. Achievements 1 2 3 Full support of IFC4.
Handling of Curtain Walls and their embedded items (Doors, Plates, Windows).
Embedded in walls
Not embedded in walls 1 2 3 12

13. ACHIEVEMENTS
3. Support for virtual space partitions (Air - space boundaries).
4. Support for external shading surfaces.
Building external shading surfaces formed by extended building architectural elements (slabs,…) beyond the building’s envelope, are identified by CBIP algorithm.
Proper enhancement of the IFC file with the geometric data of these surfaces is currently under development. 13

14. FEATURES
When input IFC4 files are corrupted, the operation of the platform terminates and the original input IFC file is not be enhanced.
If design errors are present (clashes, space incorrect definitions, …) the quality of the space boundaries might be affected depending on the nature of the design errors.
IFC MVD checking is being developed and will be integrated.
Error detection (model checking) tool has been developed and will be added informing the user about the presence of errors (e.g. BCF).
A final BEPS model export will be also added (idf EnergyPlus file).
A modified version of the Revit IFC Exporter has been created, which allows proper IFC exportation of material properties, curtain walls, schedules. 14

15. CONCLUSIONS
A web platform for the enhancement of IFC files with the necessary building 2nd level space boundary topology for BEPS model generation is presented.
The platforms’ operation is a three stage process which involves:
Extracting the necessary data from the IFC file.
Calculating the 2nd level space boundary topology using CBIP algorithm.
Enhancing the input IFC with the space boundary topology.
The platform has been demonstrated on simple and complex geometries.
The contribution of the platform is twofold:
Accelerates the process of estimation of the energy efficiency of buildings by automating the link between BIM and building energy performance simulation models.
Supports work in the OptEEmAL project towards realization of a retrofitting decision support tool. 15

16. (Please contact me if you need access)
Thank you !
(Please contact me if you need access) 16