Thermal and perceived air quality responses between a dedicated outdoor air system with ceiling fans and conventional air-conditioning system

Abstract

Field surveys were carried out to evaluate the thermal comfort, perceived air quality (PAQ) of occupants and energy consumption in two different spaces of an actual university building, one of which is equipped with a Dedicated Outdoor Air System integrated with ceiling fans (DOAS-CF) and the other equipped with a conventional Fan Coil Unit (FCU). A total of 244 subjects (65 males and 179 females) responded to questionnaires in a design studio operated with DOAS-CF at a warmer setpoint temperature of 27 °C and a computer lab operated with FCU at a setpoint temperature of 24 °C (which is common for the Tropics). Occupants under DOAS-CF at 27 °C felt more thermally comfortable and expressed higher thermal acceptability than those under FCU at 24 °C through their behavioral adjustment in choosing their sitting location based on their thermal and air movement preferences. With DOAS-CF, the cooling experienced by the nose has favorably inclined the olfactory sense towards PAQ; however, there is a small percentage who felt the PAQ was unacceptable as they were also thermally uncomfortably warm. Energy consumption of DOAS-CF was 27.7% lower than that of FCU due to warmer setpoint temperature. Despite creating a wide range of effective temperatures, DOAS-CF system can achieve better thermal comfort when occupants’ behavioral adaptation is empowered; it also achieves higher energy conservation by increasing setpoint temperature than the conventional mixing AC system.