Experimental study on the application of a Passive Displacement Dual Coil Cooling System in a tropical climate

Passive cooling strategies have become increasingly crucial in promoting sustainable energy use, as they minimize reliance on energy-intensive mechanical components, reduce greenhouse gas emissions, and enhance energy efficiency in building cooling systems. This study investigates the performance of a novel dual coil passive cooling system, i.e., Passive Displacement Dual Coil Cooling (PDDCC) system in a commercial hotel setting within a tropical climate. The primary motivation of the research is to quantify and compare the thermal comfort level assessment and the energy performance of the PDDCC system as opposed to the existing active cooling system, i.e., conventional Fan Coil Unit (FCU) system. The experimental study consisted of three main phases: Objective study, Subjective study, and Comparative analysis. The experiments were conducted across two hotel rooms in a commercial hotel situated in Singapore. In Phase 1, The Predictive Mean Vote (PMV) was used to characterise the thermal stratification and airflow measurements gathered from the hotel rooms in the objective study. Phase 2 consisted of a comprehensive thermal comfort survey with 35 participants to assess both cooling systems. The subjective study revealed that 80% of participants found humidity levels acceptable, and 70% reported room temperatures within their preferred range of 24–26°C, demonstrating the PDDCC system’s ability to meet or exceed comfort expectations, particularly after an acclimatisation period. The thermal performance data highlighted the PDDCC system's capability to maintain more consistent and cooler indoor conditions than the FCU system. The comparative energy analysis conducted in Phase 3 of this research revealed that the PDDCC system reduces energy consumption by 26.6% compared to the FCU system, attributed to the elimination of mechanical components such as fans. These results underscore the energy efficiency advantages of passive cooling strategies in reducing the energy footprint of building cooling systems. However, the study also identified limitations, including the PDDCC system’s dependency on precise environmental conditions and higher water-side energy consumption, suggesting areas for further improvement in design and operation. Overall, the findings position the PDDCC system as a viable and energy-efficient alternative to conventional cooling methods, offering significant potential for enhancing sustainability in tropical commercial buildings.