## 1 Introduction  
It is common knowledge that prolonged sitting (or standing) represents a certain effort for the body. It is a bit strange that after some effort or standing for a long time, a person needs to sit down to rest, even though we know that this causes an unnatural posture for our body. Working while sitting on an office chair puts extra strain on the body, both physically and mentally, and when we consider thermal comfort, the problem becomes more pronounced. [PERSON] and [PERSON] [1] consider thermal comfort in office chairs crucial for ergonomics, productivity, health, and well-being, as it directly influences the physical and psychological states of office workers.  
The question arises whether, and in what way, different designs of office chairs' seats and backtests affect the participants' sense of thermal comfort while performing usual daily work tasks.  
Thermal comfort and thermal sensation are distinct but related concepts. Thermal sensation is a part of thermal comfort and serves as a sensory input that informs the subjective experience of comfort or discomfort. It is the immediate perception of temperature, such as feeling hot or cold, which is primarily based on signals from warm and cold receptors in the skin [2; 3; 4]. This perception is influenced by various factors, including air temperature, humidity, and individual differences, such as clothing and metabolic rate [5; 6; 7; 8; 9]. According to [PERSON] et al. [10] office chairs influence thermal comfort because of their impact on the heat exchange between the human body and the environment. The design and material of office chairs can influence the thermal insulation they provide, which in turn affects the user's thermal perception and comfort [11]. Chairs with different insulation values, such as foam, mesh, and gel, have been studied to understand their impact on thermal comfort, although no significant differences were found under controlled conditions [10].  
However, the choice of chair can still play a role in individual thermal perception, which is essential for maintaining comfort and reducing fatigue [9]. [PERSON] et al. [12] found that health and well-being are affected by thermal comfort, as inappropriate thermal conditions can lead to thermal stress.  
Thermal comfort is defined as the condition of mind that expresses satisfaction with the thermal environment, which include ambient temperature, air humidity, and ventilation, and it plays a role in both health and productivity, particularly in office environments where individuals spend time engaged in sedentary activities [6; 13; 14; 15; 16; 17]. The thermal assessment of office chairs is important for improving occupant comfort and reducing energy consumption in office environments [18]. By optimizing the thermal properties of office chairs, it is possible to enhance user satisfaction and achieve significant energy savings [18; 19].  
The human body regulates heat through a complex interplay of physiological and behavioral mechanisms [1]. Psychological and physiological factors, such as individual preferences, age, sex (which further emphasizes the need for adaptable ergonomic solutions in office environments), and acclimatization, can modify perceptions of thermal comfort [4; 20]. The body's heat balance is maintained by ensuring that the heat produced through metabolism is equal to the heat lost to the environment, a concept central to [PERSON]'s heat balance model, which integrates physiological processes such as the sweat rate and skin temperature to predict thermal comfort [5].