## 4 Discussion  
The integration of Building Information Models (BIMs) and Virtual Tours (VTs) in the Architecture, Engineering and Construction (AEC) industry represents a significant advancement, particularly within Computer-Aided Facility Management (CAFM) and Computerized Maintenance Management Systems (CMMSs). The varying levels of detail required in BIMs at different building phases, combined with the potential of VTs to enhance BIMs and IoT-based CAFM, are crucial areas of development. The case study of the CELLS facility provides a practical example of this integration, showcasing flexible monitoring and remote control through IoT devices and VT models. This research aligns with current trends in the field, focusing on CAFM and CMMSs in relation to BIMs and IoT [35,73]. However, the exploration of VT's potential to enhance BIMs in IoT-based CAFM is a relatively new area, laying a strong foundation for future research and developments. In relation to CAFM systems using VR, it can be stated that the VT offers a user-friendly interface based upon a common web application, which can be easily mastered by any CAFM professional, independently of their technical skills. Daily manipulation also seems much simpler, only requiring a computer device connected to the hosting network. In contrast, VR requires sophisticated equipment, including VR helmets, performant graphic cards, and fixed stations. Troubleshooting for VR is also more frequent and often requires the physical presence of technicians [21,22]. In relation to CAFM systems using AR, VTs enable remote control. Most applications using AR evidently exploit the in-site lead of the technology, by superimposing data to the space information, which is being registered by the device's incorporated camera (i.e., a tablet or a smartphone). Access to data using AR is, therefore, only useful if the user is physically present in the implicated space [23,25]. In contrast, VT interfaces can provide full functionalities, both remotely and in-site. In relation to CAFM systems using BIMs, the advantage provided by VTs lies in the realism of their detail and the relative ease with which they can be updated. To save time and machine-power consumption, CAFM users often require AEC professionals to deliver BIMs at LOG 300 or less and LOI 400-500. AEC professionals often use the room entity (i.e., IfcSpace) to associate most related information, including furniture, equipment, and other types of facilities for which no geometrical representation is modelled [1,2,4]. Therefore, a facility manager solely using BIMs will not have visual control of the specificities related to elements such as projectors, fire extinguishers, or window blinds in a given space. In contrast, the VT can provide full visual and realistic information about the different elements of a room. Moreover, if connected to the room element in the BIMs, as proposed in this article, such a layer of visual information can effectively complement the alphanumeric  
Figure 7: VT interface showing entire site orthophoto and spaces under implementation. data stored in the BIMs room (see Figures 5 and 6). In addition, and as discussed earlier, updating a VT can be largely automated, requiring only manual image capturing over time, a task that can be performed by facility managers themselves and requires little training. The methodology yielded successful results for the specific case study. Image capturing and processing remain reasonable for the service a VT may provide for CAFM purposes. The definition of linked elements, if well defined in advance by CAFM requirements, presupposes a more challenging but manageable task. Navigating a VT is smooth and user-friendly. VTs, unlike BIMs, are relatively easy to keep up to date, relying on less qualified personnel to perform the task. This offers considerable efficiency in performing CAFM routine tasks. Table 2 summarises the level of difficulty encountered during the implementation and update of the technical solution and its scale-up potential.