# Integrated Digital-Twin-Based Decision Support System for
## 2 Literature Review  
### The Specific Features and Characteristics of RMBs  
Over the past decade, the construction industry has experienced a substantial shift toward modular and prefabricated construction techniques. This evolution is driven by the numerous benefits MC offers, including reduced construction waste [16; 17], cost reduction [18], improved construction speed [19], reshaping traditional building practices, and introducing efficient, environmentally friendly methods. MC not only improves productivity but also mitigates urban disturbance [20], improves worker health and safety [21; 22], minimizes environmental impact, and fosters safer, cleaner construction environments [23]. According to the Modular Building Institute [24], modular buildings can be categorized into two main types: permanent modular buildings and RMBs. Permanent modular buildings are designed to be permanently installed at a specific site, whereas RMBs are engineered for flexibility and reusability, allowing them to be relocated and reconfigured across multiple projects [25]. This high degree of relocatability and reusability makes RMBs ideal solutions for temporary structures, such as disaster relief shelters, construction site offices, or educational facilities [26; 27]. Furthermore, with 80-90% of their components prefabricated in a factory setting, RMBs exhibit an exceptional building performance, ensuring both quality control and waste reduction [28].  
One of the most significant sustainability benefits of RMBs is their alignment with circular economy principles, particularly regarding material reuse, lifecycle extension, and waste reduction [29; 30]. Studies indicate that RMBs contribute to sustainability by reducing embodied carbon emissions [31] and minimizing raw material extraction through multiple reuse cycles [32]. For example, a study by [PERSON] and [PERSON] [33] found that MC could reduce construction waste by up to 80% compared to traditional methods, primarily due to precise factory-controlled manufacturing and the reusability of components. Similarly, [PERSON], [PERSON] [34] reported annual cost savings of approximately 23% for RMBs when modules were reused across multiple projects, as the need for new material production and on-site construction was significantly minimized.  
According to the construction process of RMBs (Figure 1), it is significant to consider the continuous loop of the reuse and relocation of RMB module units. Module lifecycle management typically follows two key pathways after initial occupancy: (1) direct relocation and reconfiguration and (2) storage for maintenance and future use. In the first scenario, the building can be dismantled and reassembled at a new site in a different configuration to suit specific project needs. The modular design enables straightforward disassembly, minimizing labor and downtime. Alternatively, in the second scenario, modules can be returned to storage for maintenance, upgrades, or standby until redeployment is required. Routine maintenance ensures their long-term usability while refurbishing extends their lifecycle. At the end of an RMB's lifecycle, modules that are no longer reusable can be recycled, further reducing the environmental impact. These practices not only optimize resource utilization but also contribute to reducing raw material consumption and waste generation.