## 3 Materials and Methods  
This study analyses and categorises existing studies on BIM and IoT integration for FM according to the methodology shown in Figure 1. To review BIM-IoT integration comprehensively in the Facility Management context, two electronic databases of peer-reviewed literature have been taken into consideration: Scopus and Web of Science (WoS). The bibliometric analysis presented here aims to analyse academic publications and trends to evaluate the existing research performance and understand patterns. As the first step, keywords to select articles on BIM-IoT integration for FM functions are defined. Table 1 highlights the keywords used to find publications on BIM and IoT. Table 2 shows the set of keywords for each FM core competence. \begin{table}
\begin{tabular}{c c} \hline
**Tools** & **Keywords** \\ \hline \multirow{2}{*}{BIM} & BIM or “Building Information Modelling” or “Building Information Modeling” or IFC\({}^{*}\) or “industry foundation classes” \\ \hline \multirow{2}{*}{IoT} & IoT or “Internet of things” or sensor\({}^{*}\) or WSN or “Wireless Sensor\({}^{*}\) Network\({}^{*}\)” or “Real Time Data” or “Real-Time Data” \\ \hline \end{tabular}
\end{table} 
Table 1: Keywords used for research in the two electronic databases of peer-reviewed literature Scopus and Web of Science (WoS). The asterisk “*” after the keywords tells the search engine to look for all the words beginning with that keywords, i.e., “sensor” tells the search engine to look for the words “sensor”, “sensors”, “sensoring”, etc... The quotations marks surrounding two or more words tell the search engine to look for the phrase and not the words, i.e., “industry foundation classes” is use to search for the phrase and not for the words industry or foundation or classes. After the keywords selection, Scopus and WoS databases were queried, using the keywords shown in Table 1, to find publications dealing with: (a) BIM; (b) IoT; and (c) BIM and IoT at the same time. This first-level query investigated how much these topics have been explored by researchers, even outside the FM field. In a second-level query on the two databases, BIM and IoT keywords (Table 1) were coupled with FM core competencies (Table 2) to measure how deep BIM and IoT permeate FM core competencies. Figure 1: Research methodology. A set of filters was applied to the various searches to limit the large number of results. To perform this selection in the WoS database, results were as follows:  
* Refined, considering the following WoS categories: \"architecture\", \"computer science interdisciplinary applications\", \"construction building technology\", \"engineering civil\", \"engineering multidisciplinary\", \"environmental sciences\", \"engineering environmental\" and \"economics\" (because of Finance and Business FM core function). * Refined, considering only the following research areas: \"architecture\", \"construction building technology\" and \"engineering\". * Refined, considering only documents in English. * Refined, considering only articles and reviews as document types to acquire higher-quality documents. Articles from \"computer science interdisciplinary applications\" and \"engineering multidisciplinary\" domains were included in the review to ensure a comprehensive review of BIM and IoT device integration. Finally, the results were further filtered (by title, abstract and author's keywords) to remove articles not relevant for the research scope. To perform a similar selection in the Scopus database, results were as follows:
* Refined, considering the following subject area: \"engineering\", \"business, management and accounting\", \"energy\" and \"environmental science\". * Refined, considering only documents in English. * Refined, considering only articles and reviews as document types to acquire higher-quality documents. * Filtered, excluding irrelevant topics (e.g., medicine, chemistry, biology).