|
Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI/ASHRAE Standard 55).〔ANSI/ASHRAE Standard 55-2013, Thermal Environmental Conditions for Human Occupancy〕 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. Thermal neutrality is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. 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. Psychological parameters such as individual expectations also affect thermal comfort. The Predicted Mean Vote (PMV) model stands among the most recognized thermal comfort models. It was developed using principles of heat balance and experimental data collected in a controlled climate chamber under steady state conditions. 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. Occupants control their thermal environment by means of clothing, operable windows, fans, personal heaters, and sun shades.〔 The PMV model can be applied to air conditioned buildings, while the adaptive model can be generally applied only to buildings where no mechanical systems have been installed.〔 There is no consensus about which comfort model should be applied for buildings that are partially air conditioned spatially or temporally. Thermal comfort calculations according to ANSI/ASHRAE Standard 55〔 can be freely performed with the CBE (Thermal Comfort Tool for ASHRAE 55 ). Similar to ASHRAE Standard 55 there are other comfort standards like EN 15251〔EN 15251 Standard 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics〕 and the ISO 7730 standard. ==Significance of thermal comfort== Satisfaction with the thermal environment is important for its own sake and because it influences productivity and health. Office workers who are satisfied with their thermal environment are more productive. Thermal discomfort has also been known to lead to sick building syndrome symptoms. The combination of high temperature and high relative humidity serves to reduce thermal comfort and indoor air quality. Although a single static temperature can be comfortable, thermal delight, alliesthesia is usually caused by varying thermal sensations. Adaptive models of thermal comfort allow flexibility in designing naturally ventilated buildings that have more varying indoor conditions. Such buildings may save energy and have the potential to create more satisfied occupants.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thermal comfort」の詳細全文を読む スポンサード リンク
|