There is no consensus about which comfort model should be applied for buildings that are partially air-conditioned spatially or temporally. The PMV model can be applied to air-conditioned buildings, while the adaptive model can be applied only to buildings where no mechanical systems have been installed. Occupants control their thermal environment by means of clothing, operable windows, fans, personal heaters, and sun shades. The adaptive model, on the other hand, was developed based on hundreds of field studies with the idea that occupants dynamically interact with their environment. It was developed using principles of heat balance and experimental data collected in a controlled climate chamber under steady state conditions. The Predicted Mean Vote (PMV) model stands among the most recognized thermal comfort models. The thermal comfort temperature may vary greatly between individuals and depending on factors such as activity level, clothing, and humidity. Psychological parameters, such as individual expectations, also affect thermal comfort. The main factors that influence thermal comfort are those that determine heat gain and loss, namely metabolic rate, clothing insulation, air temperature, mean radiant temperature, air speed and relative humidity.
Thermal neutrality is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC ( heating, ventilation, and air conditioning) design engineers.
Both the hot and cold scenarios lead to discomfort. In cold environments, the body loses more heat to the environment and in hot environments the body does not release enough heat. The heat transfer is proportional to temperature difference. The human body will release excess heat into the environment, so the body can continue to operate. The human body can be viewed as a heat engine where food is the input energy. Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation ( ANSI/ASHRAE Standard 55). For other uses, see Comfort zone (disambiguation). This article is about comfort zones in building construction.
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