## 1 Introduction  
Winter climate change and the reduction of the Arctic ice cover open up prospects for the development of Arctic routes and the expansion of raw material extraction, which require the effective protection of people from the cold. Due to the intensification of work and occupancy in these regions, even for people who generally do not have to deal with these weather situations, it is necessary to develop a new type of highly efficient but still comfortable and wear-friendly clothing. Existing protective clothing uses heat-insulating components made of various fiber materials, among which are cellulose-based fibers, synthetic fibers, inorganic materials, and high-performance polymer fibers [1], as well as natural fibers. The previous cold-protecting garment followed the concept of using more conventional insulation materials made of synthetic textiles, often from polyester [2], fleece, or natural down [3]. The thermal insulation effect of such materials depends on their thickness, which must be increased with a decrease in the temperature of the environment. As a result, the clothing became thicker and heavier. A promising concept to enhance heat insulation without an increase of the garment's weight is the utilization of infrared reflective textiles, which reflect the radiation flux generated by human body. The present work is aimed at the creation of a new generation of protective clothing made of textile fibers, which integrates a novel infrared reflective (IR) layer based on nickel or copper coating. Such IR layers would have high thermal reflection. The subdivision of clothing into areas with IR reflective layers is determined on the basis of hygien and ergonomic criteria. As shown in [4], closing deformation caused by the wind should be taken into account. The use of IR-reflective materials in clothing has been the subject of research by scientists from different countries. There are works in which IR-reflective materials are considered as a tool for influencing human health, without highlighting their effect on heat exchange in clothing [5]. There are works in which a general improvement in the thermal properties of clothing has been experimentally shown under real cold conditions [6]. For such a garment, a copper nanolayer can be applied to the surface of a light polyester nonwoven textile which has a layered structure [7]. Obviously, the positive effect of combining IR materials with common insulation is determined by the properties of the whole sandwich clothing structure. A similar approach was chosen by some authors in the study of equipment for the Arctic regions, in which materials with IR-reflective coatings were used. Such studies (see, for instance, [8]) were carried out on the basis of a comparison of ready-made clothing samples, among which the positive effect on its overall thermal resistance was shown by samples in which there was IR reflection, as opposed to those without reflective details. General test evaluations of the positive function of reflective materials confirm the prospects of using such materials in clothing to protect against cold, but require a deeper understanding of the processes of heat and moisture transfer in the layers of the clothing. According to previous investigations, a reflectivity of up to 95% (corresponding to the emissivity of 5%) can be achieved with the nickel coating [9]. In reality, this result has not been achieved due to the presence of the air layer between the textile structure and the IR reflection surface in the inner layer of the protective clothing. However, already with a reflectivity of about 80-90%, a substantial reflection of the body heat radiation can be attained. The increase in the insulation effect by this IR reflection layer (see [10]) can be up to 10% with a reflectivity of 80%.