## 2 BIM and DT Idea and Applications  
For many years, the construction industry has been convinced that BIM is an approach and tool that primarily improves the design processes and effective implementation of mod \begin{table}
\begin{tabular}{c c} \hline \hline
**Abbreviation** & **Extension** \\ \hline AI & Artificial intelligence \\ BaaS & Building as a service \\ BACS & Building automation and control system \\ BAS & Building automation system \\ BIM & Building information modeling \\ BMS & Building management system \\ CMMS & Computerized maintenance management system \\ DSM & Demand-side management \\ DSR & Demand-side response \\ DT & Digital twin \\ DTaaS & Digital twin as a service \\ FM & Facility management \\ HVAC & Heating, ventilation, air conditioning \\ ICT & Information and communications technology \\ IFCs & Industry Foundation Classes \\ IoT & Internet of Things \\ ML & Machine learning \\ RES & Renewable energy sources \\ SRI & Smart Readiness Indicator \\ TBM & Technical building management \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Important abbreviations used to write this article that appear in the text. ern buildings. The utilization of digital models of building structures, their installations, and their system infrastructure facilitate the collaboration of designers and contractors from various industries, thereby reducing the time required for completion of the project while simultaneously enhancing the quality of the final product [29; 30]. Nevertheless, the technological advancements that have occurred over the past decade or so, encompassing the evolution of computer techniques, the development of advanced engineering software, and innovative technologies of building infrastructure systems, have led to the expansion of the areas of BIM applications also during the period of buildings' operation. At present, numerous industry experts and engineering teams emphasize that BIM can be used at any stage in the life cycle of a building or infrastructure, from design to operation, as indicated in both [30; 31], summarized in Figure 1.  
The results of these research studies indicate that modern building design, and in particular smart building design, comprises the following stages where a BIM approach can be implemented:  
1. The planning and design: This stage determines the purpose of the building, its functions, and how smart technologies can be integrated. At the design stage, the following aspects are typically considered in depth: a thorough analysis of the shape, geometric shape, and appearance of the building to assess the strength and stability of the building components. By designing heating, ventilation, air conditioning (HVAC), plumbing, and electrical systems, it ensures optimal use conditions and energy efficiency. The assessment of the environmental and energy impact of a building allows for the minimization of such impact. Considering building orientation, window-wall ratio and additional analyses, BIM allows engineers to create buildings that are not only functional and aesthetic but also sustainable and energy-efficient [31]. 2. The production and transportation of material: The necessary building materials, including those specific to smart building systems, are manufactured and delivered to the site. 3. The construction: This stage involves the physical construction of the facility and the installation and integration of intelligent building technology and systems. The implementation of BIM at the construction stage encompasses monitoring of construction progress and occupational safety and health issues [32]. 4. The operation and maintenance: Once completed, the building is used. This phase encompasses regular maintenance and maintenance of both the design itself and the intelligent systems. BIM after construction involves monitoring the functioning of a building, usually with a DT, and using the IoT with machine learning (ML) [33].