## 1 Introduction  
Although the problem of the thermal load of people employed in hot microclimate conditions is known [1; 2], there is still no solution for an individual cooling system that would comprehensively meet existing needs. Systems using phase change materials (PCMs) are characterized by a limited operation time, depending on the transition time, as well as a relatively low efficiency that is tightly connected to the incorporated weight of PCMs [3]. In the case of air cooling systems, either air fans [4] or compressed air bottles [2] are used. However, the former provide only ventilation (the air is not cooled), while the latter are heavy, causing a significant additional load. Liquid cooling requires a separate cooling unit with a compressor that limits workers' mobility [1]. On the other hand, thanks to the significant miniaturization and technological progress observed in recent years in the field of wearable electronics, the use of thermoelectric coolers (TECs) for the considered purpose seems to be a promising direction. TECs are based on the thermoelectric or Peltier effect, which occurs when two materials with different thermoelectric coefficients are combined [5]. TEC devices consist of a number of alternately arranged pairs of n- and p-type semiconductors sandwiched between two, most often ceramic, plates that conduct heat but are electrical insulators [6]. Such a pair of n- and p-type semiconductors that are connected electrically in series and thermally in parallel is termed a thermoelectric module [7] or a Peltier module. Cooling with the use of thermoelectric modules has many advantages over conventional cooling methods, particularly for use by humans in portable equipment. Thermoelectric module systems tend to be lighter in weight and smaller in size [8]. Moreover, they generate no noise and do not use toxic chemical refrigerants such as freon [9]. Moreover, a TEC can act not only as a cooling device but also as a heating device, with switching between the two modes being easy to achieve [7]. The research described in the literature shows that cooling systems based on the thermoelectric phenomenon are able to stabilize the microclimate temperature under clothing during physical activity, which confirms the effectiveness of their operation [10]. In addition, the reliance on electronic solutions provides the ability to easily monitor and control the temperature in the microclimate under clothing to ensure thermal comfort [11]. Therefore, protective clothing with TEC modules can also be used in a smart working environment as one of the Internet of Things solutions. There are reports in the scientific literature in which TEC modules have found practical application in clothing with a cooling function. An example of such use is the jacket developed by [PERSON] et al. (2016) [7]. In this jacket, the links are used as an element that receives heat from the liquid that cools the user's body through a system of pipes distributed on the inside of the garment. A very interesting solution is also a jacket that allows both cooling and heating of the user's body depending on the user's needs, developed by [PERSON] et al. (2017) [11]. It is a battery-powered system with a built-in temperature sensor that measures the internal temperature of the vestibular; the cooling and heating effects are ensured by traditional Peltier modules with fans in the jacket. Clothing with a cooling function using highly efficient flexible thermoelectric coolers was developed by [PERSON] et al. (2019) [12]. The authors proposed a vast and a headband to be used directly on the body. The proposed solution is characterized by a small size, high flexibility, and low weight (0.56 g/cm\({}^{2}\)) and has the potential to reduce electricity consumption compared to collective air-conditioning devices. These reports indicate that the use of thermoelectric modules in cooling clothing is a promising direction of research; however, the use of flexible TEC modules for this purpose is still limited.