ASHRAE Terminology

the volume of a building that exchanges air with outdoor (ambient) air. The building volume is the space that is deliberately conditioned for human comfort (ft³ [m³]).

the volume of a building that exchanges air with outdoor (ambient) air. For the purposes of this standard, the building volume is the space that is deliberately conditioned for human comfort.

treating air to control its temperature, relative humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space.

chart showing operative temperatures with dry-bulb temperatures, relative humidities, and air motion by which the effects of the various conditions on human comfort may be compared.

environmental condition in a space such that the majority of the occupants should, on a statistical basis, be comfortable.

refrigeration for comfort, as opposed to refrigeration for storage or manufacture.

index combining the properties of an environment for evaluating the sensation of comfort of occupants, equal to 15 plus 0.4 times the sum of the dry-bulb and wet-bulb temperatures in degrees Fahrenheit. See also thermal comfort.

(1) operative temperature. See temperature. (2) range of effective temperatures under which most of a group of people feel comfortable.

that part of a building that is heated and/or cooled and/or humidity controlled for the comfort of occupants. Compare unconditioned space.

technology or systems used to store cooling capacity. Normally applies to comfort or air-conditioning applications. Compare to cold storage and ice storage.

processes with environmental control needs that are more constrained than occupancy comfort parameters. Examples of typical processes or areas that have unique needs and are thus critical are as follows: printing, papermaking, textiles, computer rooms, broadcasting studios, food processing, medical and hospital areas, cleanrooms, controlled laboratories, unusual safety and health needs, potentially explosive areas, cold storage, milling and machining, casting, glassmaking, and other specialized manufacturing or process spaces.

a system of computer applications used by building engineering staff to monitor, control, and optimize the building's operating performance (e.g., energy consumption, occupant comfort levels). EMS optimizes building operating performance through supervisory control programs that utilize core BMS functionality.

systems that primarily use a combination of mechanical equipment, airflow, water flow, and electrical energy to provide heating, ventilating, air conditioning, filtration, humidification, and dehumidification for the purpose of human comfort or process control of temperature and humidity.

instrument for assessing comfort environment in terms of operative temperature.

(1) a machine used to create flow within a fluid, typically a gas, such as air. (2) any device with two or more blades or vanes attached to a rotating shaft used to produce an airflow for the purpose of comfort, ventilation, exhaust, heating, cooling, or any other gaseous transport. The opening(s) may or may not have an element or elements for connection to ductwork. (3) fan consists of a rotating arrangement of vanes or blades that act on the air (impeller). Usually it is contained within some form of housing or case. This housing or case may direct the airflow or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors and internal combustion engines. Fans produce airflows with high volume and low pressure, as opposed to compressors, which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to an air stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan. (4) see also impeller.

a heating and/or cooling system that uses motor-driven blowers to distribute heated, cooled, and otherwise treated air for the comfort of individuals or equipment.

thermal storage system used for chilling processes or for comfort cooling that uses primarily the latent heat of phase change from ice to water. Ice is formed during periods of low refrigerating demand for delivery of cooling during periods of high refrigerating demand. Compare to cool storage and cold storage.

a perceived indoor experience of the building indoor environment that includes aspects of design, analysis, and operation of energy efficient, healthy, and comfortable buildings. Fields of specialization include architecture, HVAC design, thermal comfort, indoor air quality (IAQ), lighting, acoustics, and control systems. See indoor air quality (IAQ).

presence of undesired elements that are deleterious to the comfort, health, and welfare of persons or the environment (pollution includes elements such as noise, vibration, odors, and gases).

a manufacturing, industrial, or commercial procedure or activity where the primary purpose is other than conditioning spaces and maintaining comfort and amenities for the occupants of a building.

energy consumed in support of a manufacturing, industrial, or commercial processes other than conditioning spaces and maintaining comfort and amenities for the occupants of a building.

providing comfort heating for single-family living quarters.

(1) air delivered by mechanical or natural ventilation to a space, composed of any combination of outdoor air, recirculated air, or transfer air. (2) air entering a space from an air-conditioning, heating, or ventilating apparatus for the purpose of comfort conditioning. Supply air is generally filtered, fan forced, and either heated, cooled, humidified, or dehumidified as necessary to maintain specified conditions. Only the quantity of outdoor air within the supply airflow may be used as replacement air.

parameters under which the building or systems operator can adjust components of the system to satisfy occupant comfort or process requirements and the strategy for optimum energy use and minimum maintenance.

the condition of mind which expresses satisfaction with the surrounding thermal environment and is assessed by subjective evaluation. Thermal comfort is affected by heat conduction, convection, radiation, evaporative heat loss, and relative air motion.

refers to airborne concentrations of substances and represents conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse health effects. Because of the wide variation in individual susceptibility, however, a small percentage of workers may experience discomfort from some substances at concentrations at or below the threshold limit, a smaller percentage may be affected more seriously by aggravation of a preexisting condition or by development of an occupational illness. Smoking of tobacco is harmful for several reasons. Smoking may act to enhance the biological effects of chemicals encountered in the workplace and may reduce the body’s defense mechanisms against toxic substances. Individuals may also be hypersusceptible or otherwise unusually responsive to some industrial chemicals because of genetic factors, age, personal habits (smoking, use of alcohol or other drugs), medication, or previous exposure. Such workers may not be adequately protected from adverse health effects from certain chemicals at concentrations at or below the threshold limits. An occupational physician should evaluate the extent to which such workers require additional protection. Threshold limit values® (TLVs®) are based on the best available information from industrial experience, from experimental human and animal studies, and, when possible, from a combination of the three. The basis on which the values are established may differ from substance to substance, protection against impairment of health may be a guiding factor for some, whereas reasonable freedom from irritation, narcosis, nuisance, or other forms of stress may form the basis for others. (This definition reprinted by permission of the American Conference of Governmental Industrial Hygienists [ACGIH].)

space or group of spaces within a building with heating or cooling requirements sufficiently similar that comfort conditions can be maintained by a single controlling device.

those combinations of air temperature, mean radiant temperature, and humidity that are predicted to be an acceptable thermal environment at particular values of air speed, metabolic rate, and clothing insulation (Icl).