## 4 Methodology
### BIM2 BEM-Flow (2021-Ongoing): Development of the Web-Tool and Revit Plugin  
During the BIM2 IndiLight project, it became evident that merely providing standardized parameters without a functional link to tools limits the usability of the ASI Property Server. Due to the limitations of the existing database system, establishing such a connection was not possible. Consequently, the BIM2 BEM-Flow follow-up project developed a new database system (YAPS) and workflow (PWM and RWM) (Figure 1) that enables easier integration with new tools and developments. Properties from the BIM2 IndiLight project were transferred to the YAPS. BIM2 BEM-Flow aims to establish a workflow-driven toolchain for defining exchange properties between different software tools in the BIM  
Figure 7: Property definition process—method. and BEM environments (e.g., Revit to DALEC). The specified properties are automatically synchronized in the digital building model, allowing for the continued use of properties defined in BIM2 IndiLight (Figure 8). Not only does the standalone provision of standardized parameters without a functional connection to BIM or BEM tools pose a challenge, but the rigid structure of the standard property server can also be a hurdle for users in the AECO industry. Many companies have their own property lists developed over time, and tools have specific requirements for properties, necessitating a more flexible approach [46]. The lack of standardized procedures for integrating BIM and BEM, as well as interoperability issues, further complicates the process, underscoring the need for more flexible and adaptable systems. These challenges underscore the importance of developing more adaptable and user-friendly systems to meet diverse needs [47]. The main challenge for BIM2 BEM-Flow is, therefore, to offer reusable properties while maintaining the flexibility to adapt to changes. As part of BIM2 BEM-Flow, three applications were developed to support a consistent BIM workflow: (I) a web-based platform for creating, describing and managing company- or project-specific properties and their mapping (YAPS); (II) a web-based platform for creating workflows that outline a clear, comprehensive process (BIM tool, BEM tool, phase, use case, parameter library, and responsible parties) (PWM); and (III) a Revit plugin to coordinate this information within the BIM tool (RWM). This study focuses on YAPS (I). Feedback from industry partners in the BIM2 IndiLight project and practical application experience highlighted the need for a functional interface connection to demonstrate the server's practical value. A survey, conducted under the leadership of \"Digital Findet Stadt\" [48], gathered insights from architects, planners, facility managers, BIM consultants, and research offices. The survey participants were also invited to a workshop where the BIM2 BEM-Flow project concept was presented. This approach allowed for the early identification of needs and helped to specify the project requirements. In workshops and in direct discussions with participants, the project concept was well received, and further discussions helped to fine-tune the requirements. In summary, the following needs were mentioned by the industry:  
* Ease of use;
* User-friendly interface;
* Clear documentation of responsibilities (to establish trust in the data). Based on this feedback, the web-based platform for managing company- and project-specific parameters was designed and implemented. The database structure follows the IFC format, which, along with gbXML, is one of the few open exchange formats that support comprehensive building mapping and is compatible with most BIM tools currently available [49; 50]. The objective of the database developed  
Figure 8: Use of property server BIM2 BEM-Flow. in BIM2 BEM-Flow was not to provide a server with standardized parameters, but rather to create a user-friendly application where company- and project-specific parameters can be defined and managed.