## 5 Discussion  
Laboratory utility tests have shown that the developed active clothing is able to reduce the local skin temperature by up to 2.66 \({}^{\circ}\)C during intense physical activity and that the cooling effect was maintained throughout the entire study period. This reduction was in between the results of other personal cooling systems presented in the literature [14,15], which makes it possible to positively evaluate the developed solution. It was lower than the one yielded by the T-shirt proposed by [PERSON] et al. [14]. This may be due to additional fabrics applied under the proposed active clothing model, which, in the considered use case, were required for the worker's safety. Fabrics constitute additional layers of thermal insulation that decrease heat conduction between the skin and the TEM. A positive effect of the applied cooling was also visible in users' sensations as thermal comfort sensation ratings decreased during the experiment to below the initial value despite the physical activity being performed. The lowest ratings, being a result of both the cooling effect and lower work expenditure, were observed during the breaks. The influence of the physical activity performed by the PCS's user on its performance was also noticed by [PERSON] et al. [12]. Skin temperature is one of the physiological indicators used for the evaluation of the human thermal state [39,40]. Its mean value of about 33 \({}^{\circ}\)C is considered to be comfortable [41]; however, local skin temperatures on various body parts can differ significantly [42]. The obtained results show that, as a result of the application of active cooling, local skin temperature values both in a cooled place and in an uncooled one (both on the torso) were kept close to the comfort one. Moreover, the applied cooling positively affects the user's thermal comfort sensations through the reduction in the temperature measured outside the TEMs. This observation is consistent with the results reported by [PERSON] et al. [14], who argue that such an effect results from the thermal conduction of the skin and the circulation of the cooled blood. This outcome is particularly important in the context of the simulations performed by [PERSON] et al. [43], who concluded that local cooling with a use of a TEM may only provide limited protection against extreme thermal environments. However, in that study, the TEM was used for cooling the air in a PCS, not the human skin directly [44]. Heat transfer mechanisms from the skin are different in both cases, i.e., direct conduction in this work versus convection of a cooling medium in [43]. According to the body map created by [PERSON] et al. [45], the cheek, back of neck, and seat area are the body regions most sensitive to cooling. However, considering the ergonomics, workers' preferences, and requirements resulting from the working conditions, the body regions selected to be covered by TEMs in the proposed PCS appear to be a good compromise between sensitivity to cooling and comfort of use. Moreover, it has been proved that local cooling can significantly contribute to overall thermal comfort sensations [46, 47, 48]. Figure 13: Proposed inference procedure. The GWEN sends the requests to two models independently and then aggregates them. Based on their research performed with 30 volunteers, [PERSON] et al. [49] also proved that local cooling provided by a wristband, besides influencing the overall thermal comfort sensation, can lead to a reduction in negative emotions and a rise in positive emotions. Under the maximum observed power consumption of 7.55 W, the 15 Ah powerbank used can supply the system for 7.35 h. This is sufficient for a typical work shift, since the PCS is normally not constantly operated at full power. Based on earlier measurements [50], the heat flux through the TEMs for a current of 0.30 A (corresponding to an electric power of 0.48 W) is 0.99 W, and it may be approximated by linear regression as 1.24 W for a current of 0.54 A (corresponding to an electric power of 1.50 W).