## 5 Discussion
### Primary Parameters  
Cooling load, or cooling demand, is the primary parameter since it directly influences a chiller's energy consumption and TCO, as the amount of cooling energy consumed is based on the required cooling demand [110]. A higher cooling load often necessitates larger or more robust chiller units to meet this demand, thereby increasing the capital costs associated with equipment purchases and installations [118]. Additionally, operating a chiller at maximum capacity or beyond its optimal range due to a high cooling load can result in higher energy consumption, operating costs, and maintenance costs over time [6].  
Energy consumption and electricity price/tariff are also primary parameters that directly impact the operational costs and TCO of CWPs [20]. As CWPs are energy-intensive systems, fluctuations in energy usage or prices significantly affect the TCO [3]. Energy consumption is influenced by various factors, such as cooling load, system cooling capacity, PLR, COP, and outside temperature, which exhibit high correlations and causations with each other [52]. Higher energy consumption increases utility costs [118], thus affecting the TCO. To effectively predict TCO, it is crucial to collect detailed energy data at high temporal resolution (e.g., every second or minute) [118; 122] and over an extended period (e.g., several years) to capture seasonal changes, unusual patterns, and related costs to energy use [30; 86]. Understanding energy usage patterns helps identify inefficiencies and facilitate TCO prediction [123]. Moreover, considering pricing strategies, such as peak pricing or demand rates, and implementing solutions like thermal energy storage can optimize cooling system operations and result in cost savings [48; 127].  
Chiller capacity/size is another primary parameter influencing both CAPEX and OPEX [6; 30; 48; 98; 113]. Larger chillers have higher initial costs, while improperly sized chillers, either too large or too small, operate inefficiently, leading to increased energy consumption and maintenance and operational costs [6; 98]. An oversized chiller can result in higher energy consumption from cycling losses. In contrast, an undersized one may force the system to operate continuously, accelerating wear and tear and elevating maintenance costs and the TCO [6]. Accurately determining a building's cooling capacity involves a detailed analysis of its characteristics, hourly or seasonal variations in cooling demand and usage, peak cooling load, and environment, often requiring professional tools and expertise [30]. Larger capacity systems can handle future demand increases but may incur higher upfront and energy costs due to inefficiencies. Properly sizing a system optimizes lifespan, efficiency, and regulatory compliance, impacting both short-term and long-term expenses [52]. Therefore, chiller capacity/size is also a critical factor in determining the TCO of CWPs.  
Another primary parameter is COP, which indicates the chiller's efficiency in converting electrical energy to cooling output [1]. Higher COP values indicate better energy efficiency, making the system more cost-effective [3; 30; 52; 126]. For example, a chiller system incurs its highest total cost when COP drops, and the tariff increases [3]. This parameter can help in the decision-making process for TCO prediction [11].