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AIC - Amperage Interrupt Capacity

A rating of maximum amperage interrupt capacity of an active device such as a breaker that is designed to safely open up under over-current conditions.


AHUAHU - Air Handling Unit

A device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An AHU is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork that distributes the conditioned air through the building and returns it to the AHU.


Major Manufacturers of AHUs

  • Carrier Corporation
  • Daikin Industries
  • Johnson Controls

McQuay International

  • Lennox International
  • Rheem
  • Trane
  • Dunham-Bush


Alternating Current (AC)

Flow of electricity which cycles or alternates direction many times per second. The number of cycles is referred to as frequency. Most common frequency used in this country is 60 Hertz (cycles per second).


AC is the form in which electric power is delivered to businesses and residences. The usual waveform of an AC power circuit is a sine wave. (green wave in image)


Amperes / amps

The unit of measurement of electrical current: a measure of the amount of electric charge passing a point per unit time.



power in watts = voltage in volts x current in amps.
power in watts = current in amps x (resistance in ohms) squared

power in watts =(current in amps)squared x resistance in ohms


A variable number used to measure a something that continuously varys, such as pressure or temperature.

ANSIANSI - American National Standards Institute

American National Standards Institute (ANSI) empowers its members and constituents to strengthen the U.S. marketplace position in the global economy while helping to assure the safety and health of consumers and the protection of the environment. ANSI acts as a U.S. standards and conformity assessment system.


ANSI oversees the creation, distribution and use of thousands of standards and guidelines that directly impact businesses in nearly every sector. ANSI is also actively engaged in accrediting programs that assess conformance to standards – including globally-recognized cross-sector programs such as the ISO management systems.

Established in 1918, ANSI's mission is to enhance both the global competitiveness of U.S. business and the U.S. quality of life by promoting and facilitating voluntary consensus standards and conformity assessment systems, and safeguarding their integrity.


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Application Specific Controller (ASC)

A pre-programmed control module which is intended for use in a specific application. ASCs may be configurable, in that the user can choose between various pre-programmed options, but it does not support full custom programming. ASCs are often used on terminal equipment such as VAV boxes or fan coil units. In many vendors' architectures ASCs do not store trends or schedules but instead rely upon a Building Controller to provide those functions



ARCnet is an embedded networking technology well suited for real-time control applications in both the industrial and commercial marketplaces. Its robust performance and the availability of low-cost silicon make it the network of choice in Building Automation Systems.


The American Society of Heating, Refrigerating and Air-Conditioning Engineers advances technology to serve humanity and promote a sustainable world. Membership is open to any person associated with the field.

ASHRAE also publishes a well recognized series of rules and guidelines (or standards) that relate to HVAC, fire, safety and lighting systems. These standards are often referenced in building codes. Examples of some ASHRAE Standards are:

    • Standard 135 – BACnet - A Data Communication Protocol for Building Automation and Control Networks
    • Standard 62.1 – Ventilation for Acceptable Indoor Air Quality (versions: 2001 and earlier as "62", 2004 and beyond as "62.1")
    • Standard 62.2 - Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings
    • Standard 90.1 - Energy Standard for Buildings Except Low-Rise Residential Buildings - The IESNA is a joint sponsor of this standard.


American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
1791 Tullie Circle, NE
Atlanta, GA 30329-2305



American Society of Mechanical Engineers
Three Park Avenue
New York, NY 10016-5990



A standards development organization that serves as an open forum for the development of international standards.


ASTM International
100 Barr Harbor Drive
West Conshohocken, PA 19428-2859


Automated Logic CorporationAutomated Logic Corporation

Automated Logic Corporation is located in Kennesaw, Georgia, and manufactures building automation systems.Several of its technological innovations include: EIKON, a uniquely powerful, universal programming tool; SuperVision, a Graphical User Interface (GUI); ALERT alarm management; Connect third-party subsystemintegration; I/O Hardware including controllers and routers; and WebCTRL, a web-based building automation system.WebCTRL


Automated Logic systems are installed in commercial office buildings, industrial plants, critical mission facilities, healthcare facilities, educational facilities, government complexes, hospitality/entertainment venues and retail locations worldwide.


Products are sold through an international network of dealers who design, engineer, install and support Automated Logic products. Automated Logic Corporation was acquired by the Carrier Corporation (parent: United Technologies Corp.) in 2004.


As a founding member of the BACnet Manufacturers Association, (now BACnet International) Automated Logic was one of the first to offer products using our industry’s standard protocol – BACnet.