Effects of elevated air speed on thermal comfort in hot-humid climate and the extended summer comfort zone

• Published in: Energy and buildings Vol. 287; p. 112953
• Main Authors: Zhou, Jinyue, Zhang, Xiaojing, Xie, Jingchao, Liu, Jiaping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2023
• Subjects: Air movement; Climatic chamber experiment; Hot-humid climate; Mean skin temperature; Mechanical airflow; Thermal comfort zone; Hot-humid climate; Climatic chamber experiment; Air movement; Mechanical airflow; Thermal comfort zone; Mean skin temperature
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2023.112953

•Quantified relations between mechanical airflow and thermal comfort were studied.•The upper limit of air speeds that did not cause draught feelings were examined.•Mean skin temperatures decreased 0.2 °C-0.6 °C for increasing the air speed by 1 m/s.•Cooling effect of mechanical airflow was restricted under humidity up to 85%.•Acceptable operative temperature range in 40%-60% humidity was extended by 1.3 °C. Indoor air movement is beneficial for building energy conservation and human thermal comfort. Chamber experiments were conducted to evaluate the cooling effect of elevated air speeds on thermal comfort. Three temperature (26, 29, and 32 °C) and two relative humidity (40%–60% and 70%–90%) levels were selected for a total of six experimental conditions. Thirty-six subjects in summer clothes (0.5 clo) were exposed to mechanical airflow produced by electric fans and experienced four 30-min exposures at various air speeds (0.01–2.0 m/s), and subjective perceptions and skin temperature were collected. Results showed that mean skin temperatures decreased by 0.2 °C–0.6 °C for every 1 m/s increase in air speed. Airflow may alleviate thermal dissatisfaction, but air speeds up to 2.0 m/s cannot eliminate discomfort in extremely hot-humid environments (29 °C/85%, 32 °C/55%, and 32 °C/85%). In the experimental conditions of 26 °C/45%, 26 °C/75%, 29 °C/55%, 32 °C/55%, and 32 °C/85%, the upper air speed limits were 1.2, 1.2, 1.6, 2.0, and 2.0 m/s, respectively. Based on experimental data, comfort zones with elevated air speed for both moderate (40%–60%) and high humidity (70%–90%) were obtained. The maximum acceptable operative temperatures in two humidity conditions were 31.3 and 28.6 °C, extending the ASHRAE 55 values by 1.3 and 0.1 °C, respectively.