Energy saving potential of ceiling fan-assisted air conditioning in tropical climates

Abstract

The cost of air conditioning in tropical climates makes the biggest contribution to the energy bill in most domestic, commercial, and industrial settings. Improving the air circulation and thereby enhancing the thermal comfort of occupants pave the way to running the air conditioners (AC) at a higher temperature setting, which leads to lower power consumption. Accordingly, this research examines whether ceiling fan-assisted air conditioning systems can reduce the energy required for cooling in tropical environments. The research is primarily based on field studies and was conducted in a typical office space in Kankesanturei, Sri Lanka, which has a year-round tropical climate with high temperatures and high levels of humidity. The office room is air-conditioned with a window-type AC, and air circulation is provided by a ceiling fan. 50 participants with almost identical clothing were selected. Testing was conducted for different AC temperature settings and different speed settings of the ceiling fan. Wind speed, temperature profiles within the room, and corresponding energy consumptions were recorded. Thermal sensation feedback from participants was also obtained via a questionnaire for each operating condition. Measurements and participant feedback were analyzed, using established ASHRAE standards to rate the thermal comfort level. According to the findings, utilizing ceiling fan-assisted AC can result in a reduction in energy usage of up to 40% (depending on the AC type, temperature setting, and the nature of the occupants). As a result of the improved airflow generated by the ceiling fans, the hybrid system provides superior thermal comfort at moderate fan speeds. This is because the increased air movement improves air circulation and reduces temperature stratification within the room. Accordingly, this research highlights the potential benefits of adding this combined system to building design and HVAC system selection, providing significant information for building designers. Keywords: Fan assisted AC, Thermal Comfort, Air Conditioner, Ceiling Fan, Office buildings.