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Preventive maintenance for mechanical, electrical, and plumbing (MEP) systems is a complex task for facility managers since each system have different requirements and their tasks involve a huge amount of data regarding location and components, as well as historical inspection and operation data. Despite the use of modern facility management systems, there are still limitations due to the lack of features required to enable data collection, data retrieval and on-site visualization. Moreover, it is necessary to establish an efficient maintenance strategy to keep building systems under a proper service level and reduce the probability of failures.
Because of this, building information modeling (BIM) has emerged as a platform to assist operational tasks by providing a digital model combining geometry and parametric information. However, BIM has limitations when accessing model information on-site. Also, the possibility to send and retrieve data in real time is limited. To overcome these limitations, emerging technologies like augmented reality (AR), combined with BIM, have been used in the operations and maintenance field providing access to information on-site.
Therefore, an augmented reality application for preventive maintenance of MEP systems is developed in this research. The aim of this augmented reality development is to aid facility engineers and personnel by providing a fully featured application needed to support the performance of their tasks efficiently and quickly. The system components and requirements are analysed to establish a preventive maintenance approach that combines predetermined and condition-based strategies. BIM model geometry is imported into an augmented reality game engine (Unity) to build the application. The user interface functions are developed using C# scripts created in Visual Studio. In addition, the MEP systems information extracted from the BIM model is stored in a cloud database. The AR system is linked to this database, allowing for real-time data exchange.
The augmented reality application is tested using the MEP systems of a university building where the functions developed improve operating tasks by overlaying a 3D model to enhance spatial analysis, highlighting an element selected by changing its color, retrieving parameters of the element selected, access to inspection and maintenance records, and automatically scheduling the next date for these tasks. It also provides a remote assistant with an instant chat connected to multiple users and presents a schedule with past, current, and future tasks that are updated in real time, as well as the possibility to report an unplanned activity or emergency. Because of these functions, the current framework could improve facility managers and staff to perform their tasks related to the maintenance of MEP systems.

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