Influence of misting system on the thermal environment and thermal comfort of seated people in semi-outdoor space in Xi'an, China

In summer, factors such as solar radiation could make semi-outdoor spaces uncomfortable, and the use of misting systems for evaporative cooling is a low-energy improvement measure. To investigate the impact of misting system on the thermal environment and thermal comfort of seated people improvement, a field study was conducted at a semi-outdoor cafeteria in Xi'an. The results indicated that the misting system was capable of reducing the ambient air temperature by 2.4–4.9 °C and increasing the relative humidity by 17.1%–17.8%. Participants in misting condition reported lower thermal sensation and higher thermal acceptability, thermal preference, humidity sensation, humidity preference and humidity acceptability. In no misting condition, the upper SET∗ limit acceptable to 80% of the population was 28.5 °C. However, in the misting condition, the acceptable percentage of participants in each SET∗ interval was more than 90%. When SET∗ was 22.1–23.7 °C, the improvement in human thermal comfort through misting system was not significant. When SET∗ was 23.7–28.5 °C, the misting system significantly improve human thermal comfort. Finally, two control temperature thresholds of the misting system were provided according to the relationship between 80%, the maximum (89.3%) acceptable percentage and the air temperature, which were 30.1 °C and 26.5 °C, respectively.