## 2 Methodology for Defining a Workflow
### Step 1: Definition of IDM OpenBIM Workflows through BPMN  
The IDM OpenBIM standard was considered to digitalize and systematize the building renovation process, as presented on the right side of Figure 1. In this regard, to streamline the digitalization of the renovation process, the Business Process Modelling Notation (BPMN 2.0) was leveraged for modelling the envisaged Use Cases. The BPMN [68] is a standard from the Object Management Group (OMG) that promotes the modelling of business processes. It provides a set of graphical elements for describing business processesbased on flowcharts that resemble the activity diagrams from the Unified Modelling Language (UML). The BPMN Version 2.0 of the standard was developed in 2010, and the current revision of the specification was published in 2013.The BPMN is meant to bring together business process design and process implementation, by providing a standard model executable in software workflow engines [69] and standard notation. This notation can be easily understood by all stakeholders, where business analysts (e.g., designers) are devoted to creating and refining the processes, technical developers (e.g., contractors, suppliers, and BIM technical experts) to the implementation, and business managers (e.g., tenants) to monitoring the business processes. These processes can be ideally driven with the support of workflow engines. The BPMN models are comprised of diagrams built from a limited set of graphical elements. They simplify the understanding of business activities and processes for both business users and technical users. The five basic BPMN element categories are [43]:  
* Flow objects: These are the main elements consisting of three core elements: Events, activities, and gateways (see Figure 2). An event is represented by a circle and denotes something that happens, compared with an activity, which is something that is to be carried out. As such, an activity is represented by a rounded-corner rectangle and describes the kind of work that must be conducted. An activity is a generic term for work that a company performs, and it can be atomic or compound, manual or automated. To finish, a gateway is represented by a diamond shape and determines the forking and merging of paths, depending on the workflow conditions expressed as variables. * Connecting objects: These are used to connect flow objects to each other. There are three types of connecting objects: Sequences, messages, and associations (see Figure 3). * Swim lanes: These are placeholders for organizing activities. There are two types of swim lanes: Pools and lanes (see Figure 4). A pool represents major participants in a process, separating different actors. A pool contains one or more lanes, which are used to categorize activities within a pool according to the function or role. * Artifacts: These are used to provide additional information about the process, as seen in Figure 5. There are two standardized artifacts, but modelers or modeling tools are free to add as many artifacts as necessary. * Data: This is represented with the four elements data objects, data inputs, data outputs, and data stores (see Figure 6). Data objects provide information about what activities are required to be performed and/or what they produce, and can represent a singular object or a collection of objects. Data input and data output provide the same information for processes. Thus, data objects show the reader which data are required or produced in an activity or task, such as the EIR needed to enable efficient exchange of information, i.e., interoperability capabilities, between stakeholders during the collaborative process. Figure 4: BPMN pool and lanes. Figure 5: BPMN group and text annotation artifacts. Figure 3: BPMN connectors. Figure 2: BPMN events (**left**), gateways (**right**), and tasks (**under**). Accordingly, the creation of the renovation workflows was accelerated by the leverage of these standard building blocks.