# Exploring the Benefits and Limitations of Digital Twin Technology in Building Energy
## 3 Background of BIM and Digital Twin
### Building Information Modelling (BIM)  
Building Information Modelling (BIM) was first proposed in the 1970s as a digital representation of the physical and functional characteristics, including various building data and information, and used throughout the life cycle of the buildings [15]. The initial application of BIM in new construction is mainly about design, visualization, coordination, and throughout project management phases [16]. Since BIM includes all the information of the structure, it is multidimensional from its nature, and each subset containing different information can be called a dimension. BIM can be mainly divided into eight dimensions, which are object model, time, cost, operation, sustainability, and safety [17]. In simple terms, BIM can be both a technology and a process; it provides a visual platform for stakeholders to better collaborate and communicate throughout a project. For traditional project collaboration, project documents, and technical drawings are manually passed between stakeholders, and subjective interpretation can easily lead to misinterpretation during information transformation, negatively affecting collaboration efficiency.  
However, the application of BIM enables stakeholders to communicate and share information through a database with a visualized model. The information-sharing process allows real-time remote communication, supported by cloud computing, significantly increasing collaboration flexibility [18]. Graphical models enable stakeholders to reach a consensus on decisions early in the project life cycle, significantly reducing project costs and improving project quality [19]. For example, converting 2D technical drawings into 3D for sharing between design and construction teams can quickly gain a common understanding of expected deliverables.  
Digital transformation drives the energy sector through the Fourth Industrial Revolution, and BIM is expected to be the core of the \"digital twin\" for actual buildings [20,21]. The application of various digital technologies such as smart meters, advanced control systems, artificial intelligence, and deep learning algorithms positively impact the management of global energy systems, and these new methods of combining different technologies and software with BIM are called Integrated Building Information Modelling (iBIM) [22] BIM has been proven to comprehensively shape digital twins when combined with methods and tools such as Augmented Reality (AR), the Internet of Things (IoT), and Big Data [23,24].  
Building Information Modelling (BIM) has also emerged as a potential solution to improve energy efficiency. Digital representations of construction processes through BIM platforms can facilitate information exchange and interoperability in digital formats. The application of digitalization and BIM can significantly improve the overall efficiency of the energy system, as well as the collaboration, flexibility, and information update throughout the building life cycle. Combining BIM with Building Energy Modelling (BEM) can save energy and costs [25].