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The amount of thermal insulation worn by a person has a substantial impact on thermal comfort, because it influences the heat loss and consequently the thermal balance. Layers of insulating clothing prevent heat loss and can either help keep a person warm or lead to overheating.
The operative temperature, which is a more functional measure of thermal comfort in a building, is calculated from air temperature, mean radiant temperature and air speed. [6] Maintaining a balance between the operative temperature and the mean radiant temperature can create a more comfortable space. [7]
Operative temperature is used in heat transfer and thermal comfort analysis in transportation and buildings. [10] Most psychrometric charts used in HVAC design only show the dry bulb temperature on the x-axis(abscissa), however, it is the operative temperature which is specified on the x-axis of the psychrometric chart illustrated in ANSI/ASHRAE Standard 55 – Thermal Environmental Conditions ...
ANSI/ASHRAE Standard 55: Thermal Environmental Conditions for Human Occupancy is an American National Standard published by ASHRAE that establishes the ranges of indoor environmental conditions to achieve acceptable thermal comfort for occupants of buildings. It was first published in 1966, and since 2004 has been updated every three to six years.
Related temperature comfort measures [ edit ] The heat index used by the U.S. National Weather Service and the humidex used by the Meteorological Service of Canada , along with the wind chill used in both countries, are also measures of perceived heat or cold, but they do not account for the effects of radiation.
The dry-bulb temperature is one of the main input for thermal comfort calculations and it is also used for assessing the heat transfer by convection. The dry-bulb temperature is an important variable in psychrometrics, being the horizontal axis of a psychrometric chart.
In building design, thermal mass is a property of the matter of a building that requires a flow of heat in order for it to change temperature. Not all writers agree on what physical property of matter "thermal mass" describes. Most writers use it as a synonym for heat capacity, the ability of a body to store thermal energy.
Clothing insulation is the thermal insulation provided by clothing. [1] [2] Even if the main role of clothing is to protect from the cold, protective clothing also exists to protect from heat, such as for metallurgical workers or firemen. As regards thermal comfort, only the first case is considered.