The chillers in the HVAC system are oversized, resulting in low part-load operating efficiency throughout the year.
HVAC systems are the largest energy-consuming and highest-investment subsystem among the mechanical and electrical systems of civil buildings, typically accounting for 40%-60% of total building energy consumption and 30%-45% of total MEP investment. As the core equipment of a central air-conditioning system, the rational selection of chillers directly determines the system's initial investment and operating costs. However, in a large number of engineering practices, oversized chiller installed capacity and unreasonable unit count configuration are common problems, causing units to operate at low load ratios for most of the year, with energy efficiency ratios far below rated values. Analyzing the root causes, designers habitually adopt the worst-case superposition method, i.e., taking the maximum hourly cooling load under extreme summer weather conditions and multiplying it by a safety factor of 1.1-1.2, resulting in calculated results far exceeding the load demand during most of actual operation. According to ASHRAE statistics, the annual air-conditioning load distribution of buildings exhibits a clear skewed characteristic; the time percentage corresponding to the design load typically does not exceed 2%, and the load ratio is below 60% for more than 70% of annual operating hours. From the perspective of codes and standards, GB 50736-2012 "Design Code for Heating Ventilation and Air Conditioning of Civil Buildings" provides detailed provisions on air-conditioning cooling load calculation methods, but most design institutes still use simplified load index estimation methods. From the perspective of operational impact, the consequences of oversized chiller selection are multifaceted. Large-capacity units start and stop frequently at low load ratios, increasing start-stop losses and mechanical wear. The power of chilled water pumps and cooling water pumps for large-capacity units is correspondingly oversized. From cost data, for a 50,000 m² office building project, if the chiller installed capacity is reduced by 15%-20% and a large-small unit combination scheme is adopted, the initial investment can be saved by approximately 800,000-1,200,000 RMB, and annual operating electricity costs can be reduced by approximately 150,000-250,000 RMB. From a maintenance perspective, the large-small unit combination scheme can also improve the system's annual operational reliability. The core measure to solve such problems is to adopt an annual dynamic load simulation method for cooling and heating load calculation, using energy consumption simulation software such as EnergyPlus, eQUEST or DeST, to output the 8760-hour hourly cooling load curve for the full year, thereby determining the chiller installed capacity and unit count configuration scheme. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance. From the systems engineering perspective of engineering management, solving this problem requires the coordinated advancement of four dimensions: institutional design, process control, technical support and cultural development. At the institutional design level, clear responsibility boundaries and operating procedures must be established, translating code requirements into executable job responsibilities and work standards. At the process control level, full-lifecycle quality supervision and dynamic correction must be implemented to ensure that the work results of each stage meet expected objectives. At the technical support level, information-based methods and intelligent tools should be actively introduced to improve management precision and efficiency. At the cultural development level, quality awareness and compliance awareness must be cultivated among all staff to create an organizational atmosphere pursuing excellence. Only by organically combining these four dimensions can the quality common problems and management chronic issues that repeatedly occur in engineering construction be fundamentally solved, achieving continuous improvement and excellence in project management performance.