Performance evaluation of intermittent air supply system: a case study in Xi’an

Abstract

Intermittent air jet strategy (IAJS) has been proven to provide a satisfactory indoor thermal climate with high energy efficiency in spaces with high occupancy density. Compared with traditional ventilation strategy, IAJS system creates heterogeneous conditions around the occupants, which complicates the relationship between thermal sensation and thermal comfort. The effect of different intermittent cycles on the thermal comfort of occupants needs to be further discussed. In addition, it is necessary to investigate whether IAJS system can play a better role in hot and humid summer conditions in China. Experiments were conducted in a chamber with two rows of seated occupants. Twelve cases were designed, including different combinations of room air temperatures (24°C, 26°C and 28°C) and intermittent period (start 90 s stop 90 s, start 3 min stop 1.5 min, start 1.5 min stop 3 min and start 3 min stop 3 min). Twelve subjects were recruited for subjective investigations. The subjects performed sedentary work and wore summer clothing. Subjective responses to the thermal environments were collected. Wind speed, temperature and CO2 concentration in the occupied area were measured. The results show that IAJS has a potential to be used as a primary ventilation system primary ventilation system such as classrooms in China. When the indoor air was set between 24°C and 26°C, IAJS could create a thermal climate that made the occupants thermally neutral. Additionally, IAJS created an indoor thermal environment acceptable to most occupants, even at a setting temperature of 28 °C.