# An open-BIM Approach to IoT Integration with Incomplete As-Built Data
## 1 Introduction
### Data Integration Management  
AM processes are still managed based on outdated procedures in practice, hindering the innovation and adoption of digital technologies that could strongly support information management and contribute to the integrity, validity and interoperability of the process [19]. DTs for built environments are still in their infancy, and there are few applications that integrate static and dynamic data in AECO, which is a laggard economic sector in terms of adopting innovative digital tools [20].  
The following issues were identified regarding the lack of integration between static and dynamic information in AM:  
* BIM models are often created during the design, manufacturing, and construction phases using unclear procedures, and updated as-built models are hardly accessible or even not available. In addition to the static nature of BIM, outdated and unreliable (i.e., inaccurate and incomplete) building information impedes the full potential of the AM applications during the use phase.
* Even when updated as-built BIM data is available, scarce attention is still paid during the design phase to the information management process across the whole asset life cycle. Consequently, the information requirements (IRs) during the use phase are often not met because of the way information is created and aggregated (e.g., classified), during the design and construction phase. BIM is a flexible modelling approach, which supports the inclusion of geometries, assets and systems as part of the model. However this flexibility may result in chaos if recognisable hierarchies and classification systems are not defined in the design phase and adopted during the assets' life cycle.
* Static and real-time data are managed differently because of their nature. For instance, some asset information is designed to be static (e.g., asset locations and geometries), whereas asset performance is measured in real-time in DTs throughout the use phase. Static data is not updated frequently (or at all) and is stored in passive repositories (e.g., relational data-bases or files to query or in COBie spreadsheets). Real-time data is variable, requiring special storage and management (e.g., actively publishing new data for active subscribers). IRs are clearly different for static and real-time data, leading to AM applications that cannot use both sources of information.  
To the three main issues described above, a fourth can be added, concerning the inaccessibility of proprietary data formats: siloed black box systems that vendors use often make data interoperability impossible.  
Efforts have been made to enable more flexible data integration for AM. On one hand, several studies are currently being conducted to improve the information exchange during the lifecycle of the assets within the openBIM approach [21]. OpenBIM indicates the use of BIM based on open standards and workflows to improve the openness, reliability and sustainability of life-long data and enable flexible collaboration between all stakeholders. An example is ongoing standardisation efforts by the International Organisation for Standardisation (ISO), on the 19650 series of standards [4; 5; 6]. On the other hand, quality AM processes are being investigated using incomplete and inaccurate information, particularly on existing assets.