Environmental Factors Affecting Thermal Comfort

1. Introduction Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI/ASHREE Standard 55). There are six primary factors that directly affect thermal comfort that can be grouped in two categories namely personal factors and environmental factors. The personal factors are metabolic rate and clothing level, the environmental factors are air temperature, mean radiant temperature, air speed and humidity. The metabolic rate is decided by the human activity level and the heat loss from the body is decided by the clothing insulation value, the speed of body movement, openings in clothing and climatic conditions. The amount of thermal insulation of clothing

There are four modes of heat transfer to maintain the thermoregulation of the human body, namely conduction, convection, radiation and evaporation. A clothing system which is suitable for one climate may not be suitable for another because the clothing thermal insulation required is different for each climate. (Ogulata, 2007) Compared with Cotton long sleeve shirt, polyester long sleeve shirt produced greater sweat removal efficiency and less sweat retention in clothing during physical exercise, but thermo physiological and subjective sensations during the intermittent high-intensity exercise were similar for both fabrics. However, skin temperature returned to the pre-exercise level faster, and the thermal and rating of shivering/sweating sensation were lower after exercise in the warm and humid environment in subjects wearing polyester than when wearing the more traditional Cotton fabric. (Brazaitis, Kamandulis, Skurvydas, & Daniuseviciut, 2010) Arezes , et al., 2013 in their study on testing thermal comfort of trekking boots revealed that the subjective perception of thermal comfort appears to be more related to the increase in temperature of the feet than to the moisture retention inside the boot. Although the evaluation of knits used in the boots indicated that a particular combination of fibers was optimal for use in the inner layer, the subjective and objective evaluation of thermal comfort revealed

(Havenith, et al., 2008)In the studies on sweat secretion from the human torso during passively induced and exercise-related hyperthermia in hot environments, it was reported that the mean regional sweat rates over the whole exercise duration from high to low were lower back, upper back, shoulders, chest, and abdomen and lateral torso. (Machado‐Moreira, 2011) The sweat rate at the lateral torso was about 50 % of that on the lower back, 53 % of that on the upper back, 61%of shoulder, 64% of that on the chest and 74 % of that on the abdomen. More recently, in a series of studies on Body mapping of sweating patterns in both male and female Caucasian athletes were carried (Smith, &Havenith, 2011; Smith,& Havenith,2012) Another researcher investigated the upper body sweat rate of ten male Koreans and found that local sweat rate in the anterior upper body was lower than the posterior upper body. (Park, & Yoo, 2012) The central upper body locations have a higher sweat rate than lateral upper body sites. Since sweat producing and evaporative cooling vary across the