# Exploring the Benefits and Limitations of Digital Twin Technology in Building Energy
## 1 Introduction
### The Importance and Applications of Building Energy Management  
The application of digital twin technology has contributed positively to this. The industrial process sector accounts for 35.2% of global CO2 equivalent emissions, and 69% of these are directly related to industrial energy use, highlighting the need for immediate action to reduce industrial energy consumption and emissions. Digital twin technology has great potential to provide the best physical solution to support plant operations and asset management to effectively address the energy emissions challenge [9].  
Digital twin technology has become increasingly crucial for managing buildings' energy consumption in recent years. This innovative technology allows managers to monitor the energy usage of building facilities, including lighting, plug loads (already accounting for 33% of total energy use in commercial buildings, [10] and HVAC systems. In this way, they can understand and optimize building energy consumption patterns in detail. It is worth mentioning that the commercial and office sector accounts for 71% of total global energy consumption, of which at least 18% is used for lighting, accounting for 20% of global energy consumption [11].  
As a result, the annual energy use of an office building is influenced by many factors, including location, equipment uses, hours of operation, HVAC systems, and lighting technology, which makes improving the energy efficiency of lighting systems, while ensuring lighting quality and illumination, a key area for green building energy efficiency research [12].  
In addition, digital twin technology can simulate the operating state of devices and systems to optimize their operation in real time, thus improving energy efficiency. This feature makes the digital twin powerful technical support for energy-saving efforts. In addition, the predictive maintenance function of digital twins can anticipate and deal with possible equipment problems in advance, avoiding energy waste due to equipment failure and thus saving maintenance and repair costs.  
Digital twin technology can simulate the energy performance of different design options during the planning, design, and construction phases of a building, providing designers with a basis for making more energy-efficient decisions. It can also generate comprehensive energy usage reports and forecasts, which provide an important reference for developing energy management strategies. For example, during the construction phase, the digital twin can simulate the characteristics of utilities to enhance the operation, maintenance, and lifetime of facilities, and combine real-time data such as building information and building automation systems to accurately reflect the actual performance and energy consumption of the building [13].  
Combined with an intelligent building management system, digital twin (DT) technology automates a building's energy use, thereby achieving energy savings and reducing carbon emissions. At the same time, DT technology helps reduce operating costs by improving energy efficiency and reducing maintenance costs, which in turn improves the economic efficiency of buildings. In addition, the advantages of DT technology are reflected in ensuring low-carbon production, mitigating the impact of economic activities on carbon emissions, testing energy strategies online, monitoring abnormal energy consumption, and warning of high-emission behaviour. Together, these benefits and applications highlight the key role of DT technology in driving environmental goals and improving energy efficiency [14].  
Overall, the role of the digital twin in building energy management is indispensable. It not only helps us understand and manage the energy use of buildings in greater depth, driving energy efficiency, and environmental goals but also significantly improves the economic efficiency of buildings. Therefore, we should fully utilize and develop digital twin technology to achieve more efficient and environmentally friendly building energy management.