In order to plan and develop effective Building Information Models, it is important to consider the different uses that each discipline model should perform during the entire lifecycle, through design, construction, operation and maintenance (O&M) and decommissioning.
In BIM projects, geometric and alphanumeric information are usually defined for different objects at different project stages. However, these requirements do not necessarily align with defined BIM Uses leading to either under-creation of data or more detrimentally the over-creation of data. This can create potential issues as for different purposes, information requirements might change. For example, the information required for a wall in order to perform energy analysis is different from the one required for structural analysis. In addition, in common practice, the so called ‘LOD’ (e.g. 100-500) is defined but it is not easy to effectively check it.
The aim of this research project is to use Solibri Model Checker (SMC) to automatically verify the objects within Building Information Models against agreed requirements related to different project stages taking into account specific purposes (BIM/Model Uses). In this work the terms BIM Uses and Model Uses are used as synonyms.
The link between required information and their purpose is a key element of the work that is being undertaken at CEN level where members of 12 countries are working under the coordination of Marzia Bolpagni, a PhD candidate at the Politecnico di Milano. At ISO and CEN level, a new term is being discussed to describe the required information: Level of Information Need (LOIN). ISO and CEN standards are still under development, however Switzerland has already incorporated the term into the national BIM standard.
Harpaceas Team together with Marzia Bolpagni presented this work in Oslo in December 2017 to the European Committee for Standardization (CEN/TC 442 WG2 TG1) that is currently working on Building Information Modelling standardisation. Harpaceas has been joining workgroup tables at UNI, the Italian Standardization Body, since 2014 and is actively following the European work at CEN.
In Building Information Models, each model element should contain required properties closely connected to the chosen BIM Uses.
Example BIM Uses are:
1 Accessibility Analysis
2 Acoustic Analysis
3 Augmented Reality Simulation
4 Clash Detection
5 Code Checking and Validation
A comprehensive list of BIM Uses (Model Uses) has been developed by the BIM Excellence (BIMe) Initiative and it has been used as a reference in this work. BIMe Initiative is a unique research-based approach to digital innovation in the construction industry. It provides an integrated methodology and a modular language for performance assessment, learning and process optimisation. The BIMe Initiative offers several free contents beside as a list of Model Uses including an online BIM Dictionary available in 14 languages and a BIM Maturity Matrix.
In order to perform an effective checking process, a workflow has been defined. The following diagram shows the main steps that are undertaken using SMC.
IFC models are generated from the native authoring software. They are then loaded into SMC and assigned to an appropriate discipline. This one federated model then contains all the appropriate discipline models. It is also possible to assign an author to each model.
Classifications are then created within SMC to identify each model element. Thanks to the Classification function within SMC, it is possible to use pre-defined classifications, such as Omniclass, Masterclass and Uniclass, or customised work-breakdown structures.
In the BIM documentation, for example client’s requirements and/or BIM Execution Plans, it is important to specify specific BIM Uses based on specific needs. An excel table defining these uses can be included in BIM documentation and then imported into the classification tool within SMC. Thanks to this procedure, SMC will automatically check only rulesets related to specific BIM Uses avoiding a manual selection. In this research, BIM Uses reported in Bimexcellence.org were included as a reference.
For this case study, the “BIM Use 4050 – Code Checking &Validation” has been selected. Each BIM Use contains elements that should be checked against specific needs.
The requirements for each element use are listed in a separate Excel file that can be included in project BIM documentation.
The requirements can be divided into Geometric Requirements (LOG - Level of Geometry) and Alphanumeric Requirements (LOI - Level of Information). Currently there are several classifications (Bolpagni, 2016; www.bimthinkspace.com/2016/07/the-many-faces-of-lod.html). In the proposed workflow, it is possible to use customised levels following national or project specific needs (e.g. 100-500 as in the USA or 1-7 as in the UK or 0-6 as in Denmark). During this research, a customised scale for the Levels, with an alphabetic reference system (A to G) was used according to the Italian BIM specification (UNI 11337:2017-2).
In order to check the Level of Information Need, it is important to define the information needed for each element. The file can be uploaded into a classification in SMC and it is possible to link each element (wall, window, space…) to its specific requirements that can be grouped in different levels. For example Spaces (IfcSpace) have to comply with properties included in level B while Windows (IfcWindows) with level C properties. Different levels (e.g. A, B, C, D, E, F and G) need to be detailed in the rulesets. The use of levels can be helpful as a generic reference, however in order to check the LOIN, specific requirements must be defined. Only requiring a generic level (e.g. B) without defining specific requirements (e.g. a space should have a name and number), does not make sense.
Excel tables with properties are user-specific and their content can be amended to match project specific requirements (e.g. included in the BIM Execution Plan or Employer’s Information Requirements). Thanks to the use of these tables in the classification tool, only required levels will be activated during the check.
Several rulesets are run that automatically check the elements against their chosen BIM Uses. The elements would be checked according to the following diagram:
As shown in the following picture (Ruleset Folders), each ruleset has been divided into LOG and LOI: these two levels include all the requirements for every LOIN and for each of the model elements.
First the rulesets check that the property exists for each appropriate element related to that specific LOI or LOG. The following example shows a ‘pass’ for a rule checking that a use has been assigned to each space. Additional rules can be run to check that the value of the property is correct. Currently the check of the Level of the Geometry has not be performed in this work.
At the end of the check, elements with missing (undefined) LOIN Requirements will be highlighted as issues and properly listed in a report including images and comments. Image 10 shows an example of an incorrect value in the use of a space, detected by the specific rule. This error is easily identified in the results panel with a red triangle and could then be included as a slide in a presentation and then sent to the model author for correction.
Tasks can be included in the rulesets to guide users through the process.
After checking that all relevant properties are present and valid, it is possible to perform the last check on a specific BIM use. As mentioned before, this test deals with the BIM Use “4050 – Code Checking & Validation”.
Finally, slides for all detected issues can be created, and it is possible to export the complete report to PDF/XLS/BCF formats and send it to the model author/person responsible for inputting the information in order to resolve the outstanding errors.
This research illustrates a new way of checking information within Building Information Models against a specific BIM Use. Using SMC, this work shows that an automatic check of specific parameters is possible. In order to check the Level of Information Need, it is essential to specify the requirements in detail (e.g. all doors should have Fire Rating property), general levels such as 100-500 or A-G are not enough.
SMC allows for a powerful quality assurance process, enabling an automatic and smart check that ensures the compliance between Building Information Models and selected BIM Uses.
SMC can be effectively used to automatize the control of models against BIM requirements included in standards such as the Italian standard UNI 11337:2017 that defines specific element progression levels.
The authors would like to thank Mark Thompson from Mace for his proofreading and suggestions to the article and Solibri Inc. for providing initial materials on LOD rulesets.