Thermal comfort general

Humans and the other warm-blooded animals have developed thermoregulatory systems to carefully control body temperature to levels that enable them to function and survive effectively. In general, thermal comfort occurs when the physiological effort to control body temperature is minimized for the activity. Table. 5.1... 

In general, when a person is thermally comfortable, the person s thermal sensation for the whole body is at or near neutral as depicted in Fig. 5.7a. As we have seen, the thermal conditions necessary for comfort are affected by clothing insulation. Figure 5.7b shows the range of temperatures and humidities... 

The numbers of dissatisfied persons in Table 6.3 are not additive. Some of the people experiencing general thermal comfort (PMV-PPD) may be the same as the people experiencing local thermal discomfort. In practice, a higher or lower number of dissatisfied persons may be found using subjective questionnaires in field investigations (ISO 10551). 

Workplace climate problems can range from excessive cold through what is generally called thermal comfort at moderate temperatures to natural high temperature and/or hot work processes . Seven main factors are involved ... 

Eigure 3 shows the winter and summer comfort zones plotted on the coordinates of the ASHRAE psychrometric chart. These zones should provide acceptable conditions for room occupants wearing typical indoor clothing who are at or near sedentary activity. Eigure 3 appHes generally to altitudes from sea level to 2150 m and to the common case for indoor thermal environments where the temperature of the surfaces (/) approximately equals air temperature (/ and the air velocity is less than 0.25 m/s. A wide range of environmental appHcations is covered by ASHRAE Comfort Standard 55 (5). Offices, homes, schools, shops, theaters, and many other appHcations are covered by this specification. 

Existing methods for evaluation of the general thermal state of the body, both in comfort and under heat or cold stress, are based on an analysis of the heat balance for the human body ... 

Blood perfusion rates in the skin, hands, and feet are influenced to a considerable extent by the general thermal balance of the body. Speal-man (12) measured directly the blood flow rate to the hand immersed in water at various temperatures and showed that perfusion rate declined with declining bath temperature to 10 °C. Below this temperature there was a striking increase in hand blood flow rate, which frequently attained values comparable with those observed in a water bath at 35 °C. If the subject was comfortably warm except for the hand, alternating... 

Cotton is generally called the King of fibres and has a wide variety of applications in general apparel and technical textiles. In apparel, cotton fibre is used to produce shirts, T-shirts, inner wear, trousers, jeans, etc. In most of the apparel products, cotton fibres are used alone or in blends with other fibres such as polyester, viscose, etc. In apparel purposes, cotton fibre is preferred because of its higher thermal and tactile comfort, which is suitable for a range of weather conditions. 

These are only a few of the comfort requirements that need to be considered when designing a building. In general, human beings seem to feel most comfortable when the visual and thermal conditions are within a small range (Nicol and Humphreys, 2002 Bartenbach, 2001). 

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