## 6 Conclusions  
Although still in its infancy, the construction sector's digitisation process is underway, aiming to create an ever-larger network of cyber-physical connections, supported by the abundance of sensorized and networked elements. The analysis of data generated by sensorized building components and systems will allow using connected digital models to improve future design and increase the environmental, safety and financial performance of the digitally built environment. This document provides an overview of BIM and IoT integration in FM. From a query on Scopus and Web of Science with more than 900 results, 99 articles were identified and reviewed as the most relevant references. Existing gaps and future research directions were outlined. BIM now supports many technological advances that the industry is witnessing, albeit with some limitations. Although BIM is widely used in the building design phase, there is still much to do for its use in Facility Management. Nevertheless, BIM can be considered a natural interface for IoT/real-time data implementation. Several researchers have begun to explore the potential synergy between these two environments. From the literature review, it emerges that the BIM and IoT integration research is in an early phase. Most research works are still in the conceptual stage, even though some studies are quite thorough and propose solutions tested in real-world applications. The main obstacles preventing the uptake of these new technologies include (1) in most cases, the lack of a BIM approach that meets the information requirements and fully exploits the potential of the digital model; (2) the fragmented nature of the AEC sector; and (3) shortage of real-life use cases demonstrating potential benefits. General remarks found on BIM for FM are related to the need to  
1. enhance the interoperability of data from as-designed to as-built for FM purposes;
2. review and improve IFC open standards and data specifications to satisfy data and information required for FM. Furthermore, one of the main challenges in BIM-IoT integration is coupling dynamic real-time data to the model database. In this context, future studies are needed to  
1. find a standardised way to integrate and manage data;
2. enhance further exploration in cloud computing;
3. improve other digital technologies such as Augmented, Virtual and Mixed Reality and their application in the AEC sector, integrating them with BIM  
BIM-IoT data integration has a new added value in the market: the physical object is a product that carries information throughout its life cycle. This will significantly help the construction industry, which, mimicking more industrialised sectors, has just begun its journey from being product-oriented to service-oriented. However, to take advantage of this transformation, the integration of data into BIM models needs to be managed in the best possible way. BIM and IoT studies are often based on proprietary files and closed ecosystems, where information is not yet shared openly among stakeholders. Hence, subsequent studies within the BIM-IoT integration domain should focus their attention on open data and open communication standards. On the other hand, WSN could be considered the IoT solution for monitoring and recording the physical condition of buildings and environmental monitoring management. Research has proved that both high costs and ineffectiveness of WSN devices can be avoided if information requirements (data types, data frequencies, WSN devices' location, etc.) are appropriately set at the very beginning of the asset lifecycle. The major problems encountered in the use of WSN concern:  
1. signal transmission: the number of devices necessary for the correct transmission of data and information can influence costs or be limited by the type of construction;
2. powering devices: batteries may not be efficient enough in continuously monitored devices, and the main power supply cannot always reach all devices. In conclusion, this review highlights four key areas to be further studied:  
1.