Investigation of cleanroom clothing thermal insulation by thermal manikin and impact on thermal comfort of cleanroom users

The cleanroom environment is fundamentally influenced by the required class of cleanliness, with thermal conditions not primarily set to ensure occupant comfort. The inability to adjust temperatures, combined with strict clothing policies that do not consider clothing insulation, often leads to user dissatisfaction, potentially compromising cleanliness. Without insulation values, thermal comfort assessment, prediction of comfort temperatures, or clothing optimisation are impossible. This study aimed to determine the thermal insulation of 15 frequently used cleanroom clothing ensembles for ISO 8 to ISO 5 cleanliness using a thermal manikin. For each ensemble, the comfort air temperature was predicted according to ISO7730, and the predicted mean vote (PMV) was assessed for different ambient temperatures. Thermal insulation values ranged from 0.71 clo to 1.16 clo, resulting in predicted comfort temperatures between 17.6°C and 21.1°C. The assessment confirmed that cleanroom ensembles differ in thermal insulation depending on the class of cleanliness, leading to variations in thermal perception. Different levels of thermal satisfaction, described using the PMV index, were predicted in cleanrooms with the same air temperature but various prescribed ensembles. Selecting suitable clothing can achieve thermal comfort even in cleanrooms where user adjustment of temperature is not possible. This can account for different activity levels, personal preferences, and gender, leading to higher user satisfaction and more efficient cleanroom operation. Further research into suitable textiles and alternative clothing options is suggested to improve thermal comfort, especially for higher indoor air temperatures or specific body zones.