## 3 Results Analysis
### Planning and Design Stage
#### 3.6.1 Specific Analysis of the Planning and Design Stage  
As the assembly process is not uniform across the country, there is a contradiction between standardization and customization, often with different standards between different provinces and cities and inconsistent customer demand for customization [52]. Therefore, inconsistent standards and specifications are a challenge. This requires projects to adhere to all applicable standards for consistency and compliance [53]. Therefore, designers should focus on the standardization of components at the design stage [54]. However, this task becomes more complex when multiple objectives, constraints, many pipe segments and their accessories, and changes in design requirements need to be considered [55]. In addition, space design is also a great challenge when planning and designing, and suitable access must be reserved for subsequent installation, maintenance, and other services. Crowded construction space can lead to low productivity [56], so it is essential to integrate space and construction projects. Creating a flexible schedule for space usage [57], applying 4D building information modeling solutions [58], proposing a new space planning framework [3], and developing a computational framework for optimizing the creation of piping spools [3], to improve the performance of the MEP construction process. Another issue that has to be paid attention to is control in the design planning process. Thus, [PERSON] et al. [59] proposed a model for planning and controlling the delivery and assembly of engineering orders. Additionally, a predictive model for prefabrication feasibility [60] found that prefabrication feasibility depends mainly on industry-related determinants. This informs the design of planning and control systems. Studies have shown that a system's optimal degree of modularity is closely related to module size and module division points [61], which requires careful planning and coordination between multiple parties in the planning and design. It is an informative and rigorous process, and the accuracy and timeliness of information transfer are critical. Collaboration among multiple stakeholders is also vital [53], so enhancing collaboration among all parties is a critical factor in problem-solving [62]. An integrated project delivery approach has been found to enable project participants to collaborate early in the lifecycle [63], and the development of a collaborative design platform using knowledge-based MEP information modeling and automated analysis improves collaborative design [64]. BIM/VDC (Virtual Design and Construction) is applied to install MEP components collaboratively [65]. The use of BIM technology promotes collaborative design [66]. It optimizes blueprints through automated fine-tuning [67], which can significantly reduce waste in the design, and also optimizes the design of MEP systems through MEP energy consumption analysis [67]. Ensure the project proceeds as planned and achieves the desired goals [53]. Cost issues have also been present in the planning and design processes, where cost and budget constraints are often an issue. Projects may be subject to tight budgetary constraints [68], which may compromise M&E system performance or sustainability [69]. As a result, [PERSON] et al. [70] investigated the main factors affecting costs related to co-design practices for MEP systems. Also, insufficient consideration of environmental sustainability is an issue. With the advancement of time, it is required that projects' carbon emissions and environmental pollution be effectively controlled [71]. As a result, [PERSON] et al. [61] proposed a broad framework for optimizing the construction of environmental protection systems to optimize the environmental impact. Finally, MEP systems are critical to the functionality of the building, so they must meet performance expectations in terms of comfort and safety.