## 4 Discussion  
Energy is usually wasted in the subcooling and reheating process in the traditional air conditioning system. The energy recovery wheel integrated system consumed 17.24% less energy than the simple reheat air conditioning system [3]. The primary energy saving of the desiccant-based wheel HVAC systems was up to 20%-25% compared to the conventional HVAC systems when considering the value of chillers with different energy efficiency ratios [25]. The proposed innovative concentrating photovoltaic and thermal system with a desiccant cooling system allowed greater energy savings (74%) in the primary energy required than the conventional system [26]. Our analytical results show that the daily total energy consumption of RDAC system was similar to that of the energy recovery wheel integrated system and less than that of the conventional HVAC system, which was a simple cooling and reheating air conditioning system [25]. Our results indicate that RDAC systems are more energy efficient than either conventional HVAC or LDAC systems. In the past, [PERSON] has recommended immediately improving the operating efficiency of the chilled water unit in an air conditioning system if it exceeded 1 kWh/RT [27]. The operating efficiency of the chilled water unit of all three systems in this study was 0.85 kWh/RT, indicating good equipment quality. In this study, the volume occupied by the RDAC system was the lowest, followed by the conventional HVAC and LDAC systems. As both the RDAC and LDAC systems could meet air quality requirements while achieving energy-saving goals, replacing LDAC systems with RDAC systems would conserve space, which is often an important consideration in hospital infrastructure. Additionally, this study found that the median daily energy consumption of the fan, heat pump, and other equipment in the LDAC system was the highest, followed by the conventional HVAC system and the RDAC system. A possible reason was to have additionally configured in series with the AHU in the LDAC system. To maintain the necessary degree of cleanliness in ORs, ASHRAE/ASHE recommends that the ventilation frequency should be maintained at 20 ACH or above, much higher than the ventilation rates (2-15 ACH) elsewhere in hospitals, and the air conditioning system must be equipped with two filter banks including the first minimum efficiency reporting value (MERV) (7) and the second MERV (14) to ensure the cleanliness of the OR [5]. Besides, the ASHRAE/ASHE Standard 170 indicated that the minimum recommended ventilation frequency of external air is 4 ACH, twice the external air exchange frequency of 2 ACH in other spaces within hospitals [5]. OR temperatures must be carefully controlled as overly high temperatures can cause medical personnel to sweat (which is not conducive to infection control) while too-low temperatures can cause patients undergoing long surgeries to suffer body temperature loss [28; 29]. Most building codes have strict requirements on RH levels as aquatic bacteria such as _Legionella_ spp. are less likely to survive below 35% RH, while many non-bacterial species, such as fungi and viruses, thrive in high humidity environments [30]. In Taiwan, the energy consumption of air conditioning systems accounts for 48%-55% of the total energy consumption in medium and large-sized hospitals [31]. Since Taiwan is located in a subtropical region with a damp-heat climate, Taiwanese hospitals have a particular need to reduce their air conditioning energy consumption while maintaining their ORs' thermal-hygrometric and air quality requirements. The temperature and RH levels of the RDAC and LDAC systems were more in line with the ASHRAE/ASHE Standard 170 (temperature 20-24 \({}^{\circ}\)C, RH 20%-60%) [5], and both met the French RH standard (<65%) set in 2003 [32]. Although the RH level of the conventional HVAC system exceeded these standards, this did not affect the measured airborne bacterial concentrations, similar to the results of [PERSON] et al. [33].