###### Abstract  
This study investigated the annual variation of the indoor thermal environment in a typical canteen kitchen and tried to evaluate the actual working status of the exhaust future system. Parameters were measured in the canteen kitchen, including indoor environment (temperature, humidity, air velocity); outdoor environment (temperature; humidity); exhaust fume system (temperature, airflow rate, oil fume concentration, energy consumption), and makeup air system (temperature, humidity, air velocity) from April 2019 to January 2020. In addition, we also interviewed the chef's thermal comfort in this kitchen. From the data available, we could find that 82.92% of the working hours in summer were above the acceptable range. Only 17.08% of the working hours were within the tolerance range (26-32 \({}^{\circ}\)C). The questionnaire results showed that 83.33% of chefs felt hot in summer. Most chefs' wet sensations in the four seasons were neutral, and 91.6% of the chefs felt dissatisfied with the draft sensation. In addition, 88.33% of the chefs felt the fume overflowing from the exhaust hood. This may be because the exhaust fume system of the canteen kitchen was operated under the air velocity of 9.18 \(\pm\) 1.6 m/s, and its exhaust airflow rate was 10,634.80 \(\pm\) 189.30 m\({}^{3}\)/h, which is lower than the minimum exhaust airflow rate (12,312 m\({}^{3}\)/h). The measurement results indicated that the exhaust future system could not remove the waste heat and fume pollutants effectively. indoor thermal environment; Chinese canteen kitchen; exhaust fume system; PMV-PPD; long-term test +
Footnote †: journal: Medical  
29.86 \(\pm\) 0.23 \({}^{\circ}\)C in summer, which may lead to heat exhaustion with prolonged exposure of the vulnerable group. However, compared with Western cooking, Chinese cooking usually involves frying, stir-frying, stewing or boiling food which will produce more heat and moisture [8]. [PERSON] [9] evaluated that the residential kitchen is too hot in summer, and the air temperature in the kitchen would rise by 5.3 \({}^{\circ}\)C during cooking. [PERSON] [10] reviewed the papers on the indoor thermal environment and air quality of residential kitchens in China. The results showed that the kitchens were too hot in summer, and the hood could improve the indoor environment to a certain extent. The exhaust fume system not only can capture cooking pollutants generated in the cooking process to ensure the indoor environment but also can purify the contaminated gas by combining a variety of purification technologies to meet the emission standard and prevent them from polluting the outdoor environment. Many scholars have made contributions to the relevant research of residential range hood. [PERSON] [11] compared the effects of the original exhaust hood and the air curtain exhaust hood on the indoor environment of the residential kitchen by using the CFD. [PERSON] [12] and [PERSON] [13] simulated and optimized the structure of the exhaust hood to improve its capture efficiency of the exhaust hood. [PERSON] [14] indicated that the continuous run of the fan after cooking could partially compensate for a low flow rate exhaust hood. [PERSON] [15] reported that the exhaust airflow rate has an impact on the performance of the kitchen exhaust fume system in capturing cooking pollutants and believed that there is an optimal value for the exhaust airflow rate. Compared with residential kitchens, commercial kitchens have a large amount of cooking, intensive cooking equipment, and more serious emissions of heat, humidity, and cooking pollutants. [PERSON] [16] pointed out that the ventilation system of typical commercial kitchens in China could not effectively remove waste heat and cooking pollutants. However, the United States [17] and some countries in Europe [18] already have standards specifically applicable to the design of exhaust fume systems in commercial kitchens. For residential range hoods, China also issued the national standard \"Range Hoods\" in 1999 [19].