ASHRAE comfort zones

Thermal comfort may be defined as "that condition of mind in which satisfaction is expressed with the thermal environment" (4). It is thus defined by a statistically vaUd sample of people under very specific and controlled conditions. No single environment is satisfactory for everybody, even if all wear identical clothing and perform the same activity. The comfort zone specified in ASHRAE Standard 55 (5) is based on 90% acceptance, or 10% dissatisfied. 

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. 

ASHRAE 55, Thermal Environmental Conditions for Human Occupancy. This standard covers several areas, including temperature, humidity, and air movement. Important aspects of the standard include the definition of acceptable thermal comfort. It provides information on environmental parameter considerations. The standard makes recommendations for summer and winter comfort zones for humidity and temperature. It also contains guidelines for conducting measurements. 

Personnel exposed to higji temperatures, alone or in conjimction with high humidity, can suffer from heat stress. Cold environments with high eiir velocities can cause frostbite or hypothermia. ASHRAE [11] has established comfort zone standards identifying the temperature and humidity ranges in which individuals can work comfortably and safely. Areas that must operate outside these comfort zones should be... 

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