An experimental study of thermal comfort zone extension in the semi-open spray space

Pedestrians will experience different heat stress stages from sunlight to semi-open spray space as they shuttle through stations with spray systems. There are few studies on the influence of thermal experience and thermal history of this specific environment on pedestrian thermal comfort. This study explored the dynamic physiological thermal response and thermal perception of humans in the sunlight to semi-open spray space in Qingdao, China. Meteorological and physiological parameters were measured and questionnaires were conducted. The results showed that from outdoor sunlight to semi-open spray space, thermal sensation and thermal comfort were improved, the mean skin temperature of the whole body decreased by 0.5 °C, the neutral standard effective temperature (NSET*) enhanced by 8.8 °C, and the NSET* range (NSET*R) increased by 7.3–10.2 °C. However, after 10 min in the semi-open spray space, the thermal comfort gradually deteriorated. In addition, the main meteorological factors affecting the thermal sensation in sunlight and semi-open spray space were air temperature and mean radiant temperature, and the main physiological factor was the skin temperature of the right upper arm. This study is helpful for the operation design of spray systems and the evaluation of the thermal environment in semi-open spray in cities.