ASHRAE Terminology

a device that monitors parameters used to determine the net HVAC energy consumed in conditioning an individual unit.

This is a genus that includes several hundred species of mold. Some species can cause paranasal sinus infections or Aspergillosis. Aspergillus is of particular concern in health care facilities because many patients already have compromised immune systems. If HVAC systems are not properly maintained or designed, mold growth may be likely.

a commonly used term for the person or firm that performs testing, adjusting, and balancing of HVAC systems.

primary HVAC system losses incurred and auxiliary system energy consumed in maintaining a central HVAC energy source available for consumption by all residents.

outdoor temperature the designer selects as the point of changeover from cooling to heating by the HVAC system.

process of maintaining building conditions such as HVAC systems, lighting systems, and irrigations systems, etc.

device that receives a signal from a controller and acts on the process plant to vary its operating condition in accordance with the information received. In HVAC & R systems, controlled devices typically are valves, dampers, and motors.

difference between high and low temperatures for a typical day. Used in HVAC load calculations.

HVAC systems, electrical systems, equipment, or portions thereof, used to condition ITE or electrical systems. Data center systems may also be shared, serving other data center additions or non-data-center loads.

1. A dedicated outdoor air system (DOAS) uses separate equipment to condition all of the outdoor air brought into a building for ventilation and delivers it to each occupied space, either directly or in conjunction with local or central HVAC units serving those same spaces. The local or central HVAC units are used to maintain space temperature. 2. Primary Air System

air temperature which an HVAC system or apparatus is designed to maintain (indoor design air temperature) or to operate against (outdoor design air temperature).

a computer/processor-based hardware and software system with sensors, control devices, and all the necessary components that perform some or all of the following functions: measures conditions related to the use of various forms of energy by HVAC systems, controls these conditions at selected setpoints, monitors and/or controls the energy use, provides status reports on the HVAC system's performances, and provides information for the management of a building's environment, and/or its energy efficiency and/or HVAC system maintenance. Also see energy management systems.\n

the manufacturer's rated capacity at the defined rating point for HVAC equipment. Equipment capacity should be adjusted for altitude and other effects.

clear, colorless liquid used to depress the freezing point of water for use as a secondary coolant in HVAC&R systems. Inhibitors are required to control corrosion caused by ethylene glycol solutions.

there are two main categories of fans used in HVAC&R applications: centrifugal and axial fans. Centrifugal fans types include the following: forward curved (FC), backward curved or backward inclined (BI), airfoil (AF), and radial. Axial fan types include the following: propeller, vaneaxial, and tubeaxial.

(1) the process of determining the ability of the HVAC system to deliver heating, ventilating, and air-conditioning services in accordance with the final design intent. (2) that full range of checks and tests carried out to determine if all components, subsystems, systems, and interfaces between systems function in accordance with the contract documents. In this context, function includes all modes and sequences of control operation, all interlocks and conditional control responses, and all specified responses to emergency conditions.

duct and fittings used for conveying air in residential, commercial, institutional, and industrial heating, ventilating, and air-conditioning systems.

the equipment, distribution systems, and terminals that provide, either collectively or individually, the processes of heating, ventilating, or air conditioning to a building or portion of a building.

combined end-to-end accuracy of the EMCS (energy monitoring and control system) and the accuracy with which the EMCS sensors represent the HVAC process.

a space or group of spaces, within a building with heating, cooling, and ventilating requirements, that are sufficiently similar so that desired conditions (e.g., temperature) can be maintained throughout using a single sensor (e.g., thermostat or temperature sensor).

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).

(1) more than one building system, such as lights and air distribution, combined into a common design. (2) system in which many subsystems of a building are combined into a single package (e.g., fire, security, clock, and HVAC).

devices that isolate HVAC zones so that they can be operated independently of one another. Also, a device, such as a service valve, that allows maintenance of a portion of a system. Isolation devices include, but are not limited to, separate systems, isolation dampers/valves, and controls providing shutoff at terminal boxes.

limited fill thermal element, located in the mixed air portion of an HVAC unit, which opens an electrical circuit if any one foot portion of the element reaches its setpoint (usually 35°F [2°C]). It usually shuts down the HVAC unit and/or initiates an alarm. Formerly referred to as freeze stat.

provision of information useful for management of a building environment and/or its energy efficiency and/or HVAC system maintenance.

(1) a plan for gathering of relevant measurement data over time to evaluate equipment or system performance. The plan defines specific M&V methods to be used, including baseline determination, performance period measurements, savings verification calculations, and acceptance criteria. The M&V methods chosen are consistent with the current facility requirements (CFR). During the implementation phase, a list is developed of specific instrumentation and data-gathering equipment that must be maintained at the site. During the hand-off phase, the type, frequency, and distribution of M&V reports to be submitted for approval is confirmed. (2) equipment to measure and record the parameters of the HVAC&R systems (i.e., temperature, humidity, pressure, electric current, kW, and volts). (3) gathering of relevant measurement data over time to evaluate equipment or system performance (e.g., chiller electric demand, inlet evaporator temperature and flow, outlet evaporator temperature, condenser inlet temperature, and ambient dry-bulb temperature and relative humidity or wet-bulb temperature, for use in developing a chiller performance map (e.g., kW/ton versus cooling load and versus condenser inlet temperature).

a control system, accessible from the hotel/motel front desk or other central location, that is capable of identifying rented and unrented rooms according to a timed schedule, and is capable of controlling HVAC in each hotel/motel guest room separately.

a control system that is designed to automatically adjust the start time of an HVAC system each day with the intention of bringing the space to desired occupied temperature levels immediately before scheduled occupancy.

(1) a combined appliance that does not use a water pump but relies on thermosiphon flow through the desuperheater and water heater, generally the desuperheater is mounted on the side of the water heater or at an elevation lower than the water heater. (2) a system where natural forces are utilized for HVAC purposes in lieu of mechanical/electrical/chemical sources.

A device that is powered by means of an electrical plug and matching socket or receptacle. This excludes devices that are accounted for as part of major building end uses such as HVAC, lighting systems, and water heating.

for energy compliance alternatives , a prescriptive design includes specified assumptions concerning shape, orientation, HVAC, and other system design features. The prescriptive design is compared with the proposed design using the annual energy cost method.

(1) closed-loop control as applied to processes or operations or both. Note: HVAC systems may be considered as processes. (2) control for automatic regulation of operations or processes or both.

clear, colorless liquid used to depress the freezing point of water for use as a secondary coolant in HVAC&R systems. Note: inhibitors are required to control corrosion caused by glycol solutions.

(1) all return air that is discharged directly to the outside or exhausted by separate exhaust fans. (2) building return air discharged by the air-handling unit (AHU) equipment to control building pressure when an HVAC system is operating in the economizer cycle.

a computer model that provides information on the energy-using systems in a building (e.g., HVAC, lighting, occupancy, plug loads, building envelope). The model serves as the input data for a specific computer building energy simulation program, along with weather data. When run, the computer simulation program will predict the energy use and demand in the described building for a time interval specified in the simulation model. Depending on the kind of simulation program and how it is set up to run, various kinds of output may be produced.

an HVAC system serving a single HVAC zone.

a combination of equipment and auxiliary devices (e.g., controls, accessories, interconnecting means, and termi­nal elements) by which energy is transformed so it performs a specific function such as HVAC, service water heating, or lighting.

the use of specialized and calibrated instruments to measure conditions such as temperatures, pressures, rotational speeds, electrical characteristics, velocities, fluid flows, etc., used in HVAC&R.

a systematic process or service applied to heating, ventilating, and air-conditioning (HVAC) systems and other environmental systems to achieve and document air and hydronic flow rates. The adjustment of fluid flow rates through distribution systems by manually adjusting the position of dampers, valves, etc., or by using automatic control devices to control the position of dampers, actuators, valves, etc.

HVAC system that controls the dry-bulb temperature within a space by varying the volumetric flow of heated or cooled supply air to the space.

process that alters supply water so that it can be used for process or HVAC purposes without creating undue corrosion or scaling to the piping systems and other deleterious effects.

a heat exchanger that uses the condenser water side of the system for cooling without requiring the operation of the chiller. Also a coil on the air entering side of a heat pump or HVAC unit that uses condenser water flow to precondition the entering air when conditions are favorable. See also cooling.