Building Automation Glossary

All the essential building automation industry terms from A to Z. 

Access Control 

Access control is the method commercial building systems use to manage and regulate entry to the building, a specific floor, or an individual space. Access control is typically part of a building’s security and/or automation system and may include components like scannable ID badges or a parking garage entry booth for tenants and visitors. 

Actuator 

An actuator is a device that provides physical movement in a building system. Actuators are commonly installed on valves and dampers to open, close, or modulate flow based on a control signal from a thermostat, controller, or building automation system. They are often referred to as motors, especially damper motors and valve motors.  

Air-Coil Sensor 

An air-coil sensor is an electromagnetic sensing device made of coiled wire. 

Air Cooling 

Air cooling is the process of using air to cool down sensitive environments that require precise temperature control, like data centers and operating rooms.  

Air Flow 

Air flow refers to the amount of air that is moving through an HVAC system. It is typically measured by volume, speed, or pressure. Air flow is an important metric because it can be directly tied to the health of your air conditioning units and your HVAC system. 

Air Flow Meter 

An air flow meter is an instrument or tool that measures the volume, speed, or pressure of the air in a duct. Air flow meters may be handheld, manual devices, or automated components that are installed in an HVAC system and monitored elsewhere. 

Air Flow Switch 

An air flow switch is a sensing device that detects whether air is moving through ductwork or HVAC equipment. When airflow reaches or falls below a set point, the switch changes state and can provide fan operation, enable equipment, trigger an alarm, or shut equipment down for protection.  

Air Handling Unit 

An air handling unit, or AHU, is a central HVAC unit that conditions and moves air through a building. AHUs commonly include fans, filters, coils, dampers, and sensors that work together to heat, cool, ventilate, and control indoor air quality.  

Air Purification 

Air purification involves assessing the air quality in a space and, when necessary, taking steps to improve it. These systems use components like air flow meters and gas sensors to monitor conditions and detect unhealthy air. When poor air quality is detected, the sensors send signals to the system’s control components, which then activate the appropriate mechanical equipment to improve airflow and overall air quality. 

Air Quality 

Air quality refers to the health of the air in an indoor space. It is measured using specialized sensors that can evaluate the environment for things like CO2, particulate matter, and volatile organic compounds (VOCs). Air quality is a key component of building automationsystems that helps ensure the comfort and health of building tenants. 

Alarm Management 

Alarm management is the process of configuring, prioritizing, routing, and responding to building automation alarms. Good alarm management helps operators focus on issues that require action instead of being overwhelmed by nuisance alarms. 

Analog Input (AI) 

An analog input (AI) is a controller input that receives a variable signal from a sensor or device. Examples include temperature, humidity, pressure, CO2, and flow signals such as 0-10 VDC or 4-20mA.  

Analog Output (AO) 

An analog output is a controller output that sends a variable control signal to a device. Analog outputs are commonly used to modulate valve actuators, damper actuators, variable frequency drives, and other proportional devices.  

BACnet 

BACnet is an abbreviation for building automation and control network. It is an open protocol that allows devices from different manufacturers to “talk” to each other. BACnet is essential for today’s building automation systems because it enables the use of components from multiple manufacturers and eliminates the need to replace older parts solely because of software compatibility issues. 

BACnet/IP 

BACnet/IP is a version of the BACnet communication protocol that uses IP networks to allow building automation devices to exchange data. It is commonly used for controller networks, supervisory controllers, and BAS integrations.  

BACnet MS/TP 

BACnet MS/TP is a BACnet communication method that typically runs over twisted-pair wiring and connects field controllers and devices. It is common in building automation networks where reliable, lower-cost device communication is needed. 

Balancing Valve 

A balancing valve is a specialized valve used in hydronic systems to regulate liquid flow and pressure, typically to control heating and cooling in specific areas of a building. By equalizing system pressure, balancing valves help maintain comfortable temperatures and canimprove overall energy efficiency. 

Ball Valve 

A ball valve is a quarter-turn valve that uses a rotating ball with a bored passage to start, stop, or regulate flow. Standard ball valves are commonly used for simple open/close applications because they are durable, compact, and provide tight shut-off. (For modulating control valve applications, see Characterized Valve).  

Bimetal Sensor 

Bimetal sensors are temperature-sensing devices that convert changes in temperature into mechanical movement. It consists of two different metal strips that have different thermal expansion qualities, which are then joined together. When the temperature in a space changes, the metals expand to different degrees, causing the strip to become deformed. This change is detected as movement, which is transmitted to the pointer of a thermostat, allowing it to measure temperature.  

Binary Input (BI) 

A binary input is a controller input that reads a two-state condition such as on/off, open/closed, normal/alarm, or occupied/unoccupied. Examples include flow switches, pressure switches, status contacts, and safety interlocks.  

Binary Output (BO) 

A binary output is a controller output that sends a two-state command such as start/stop, open/close, or enable/disable. Binary outputs commonly control relays, contactors, fans, pumps, and alarms. 

Boiler 

A boiler is a heating appliance that uses either combustion fuel or electricity to heat water. In a building automation system, a boiler is a key component of temperature control that keeps spaces warm. 

Boiler Control 

A boiler control is a system of hardware and software that acts as the “brain” of the boiler, regulating, monitoring, and automating the operations of a boiler. They help keep temperature and pressure levels safe and ensure that the boiler runs efficiently.  

Boiler Trim Kit 

A boiler trim kit is a packaged set of essential boiler accessories used to help install or service residential and light commercial boiler systems. Trim kits commonly include safety, pressure-regulating, air elimination, and connection component needed to support safe boiler operation.  

Building Automation 

Building automation is the use of controls, sensors, software, and connected equipment to monitor and automatically manage building systems.  

Building Automation System (BAS) 

A building automation system (BAS) - also referred to as a DDC (direct digital control) or EMS (energy management system) - is a centralized network of controllers, sensors, software, and mechanical devices used to monitor and automatically control building systems like HVAC, lighting, energy use, and indoor environmental conditions.  

Building Automation Software 

Building automation software refers to specific components of a building automation system. The software components of a BAS serve as the system’s “brain,” functioning as a central hub for programming, monitoring, measuring, and maintaining all BAS functions and peripheral systems, such as HVAC, lighting, and more. 

Building Automation Controller 

A building automation controller is a device that is specifically designed, programmed, and installed to control precise automated functions in a building. Building automation controllers receive signals from sensors, make decisions based on preset programming, and then send commands to the relevant equipment to achieve the desired outcome. 

Building Controls 

Building controls are components that manage a building’s systems, such as HVAC, lighting, automation, or security. 

Building Management System (BMS) 

Building Management System (BMS) is a term that is often used interchangeably with the term building automation system (BAS). However, there are subtle distinctions between the two. While both refer to the integrated platform that controls building-wide systems, a building management system is a broader, taking all the systems of a building, including a BAS, and centralizing the information in one place where it can be monitored and managed. 

Burner 

In a commercial building, a burner is responsible for heating the water in a boiler, which distributes and maintains heat throughout the building. Burners typically work by mixing air with fuel, which combusts and creates consistent and efficient heat.  

Burner Control 

A burner control, also called a flame safeguard, monitors and manages the safe operation of a burner. Burner controls supervise ignition, prove flame, manage startup, and shutdown sequences, and shut the burner down when unsafe flame or fuel conditions are detected. 

Burner Management System  

A burner management system is a combination of hardware and software that controls and automates burner operations, including startup, shutdown, and essential safety functions. 

Butterfly Valve 

Butterfly valves are named for the flat metal disc that rotates to regulate or shut off the flow of liquids. They are lightweight and compact, even in larger sizes, yet can handle high flow rates, making them an excellent choice for efficient operation in space-constrained installations. 

Capacitor 

A capacitor is an electronic component of building systems that stores and releases electrical energy. Within building systems, they are typically used to start and stabilize fan motors, which cool spaces and maintain comfortable temperatures. 

Characterized Valve 

Characterized valves (also called characterized control valves) combine the capabilities of ball valves with a specially designed disk, allowing for an equal percentage flow. This precise control makes characterized valves an excellent choice for environments that require stable, continuous temperatures. 

Chilled Water System 

A chilled water system uses a chiller to cool water and then circulates that water through pumps, piping, coils, and air-handling equipment to provide cooling throughout a building.  

Chiller  

In commercial HVAC systems, a chiller removes heat from a liquid – typically water – and circulates the chilled water to help cool buildings. 

Chiller Motor 

Chiller motors power the functions of a chiller in commercial HVAC systems. Their primary function is to power the compressor, which drives the refrigeration cycle, removing heat from the water and allowing the chiller to continuously circulate cool air within a building. 

Compressor 

In an HVAC system, the compressor is the “heart”; it is a mechanical device that takes low-pressure, low-temperature refrigerant vapor from the evaporator, and compresses it into high-pressure, high-temperature vapor that the condenser can use to complete the refrigerant cycle, enabling stable and continuous temperature control.  

Configurable Controller 

Configurable controllers are building control devices that come with preset functionality, meaning they do not have to be programmed with custom code. This makes configurable controllers a great choice for cost-effective and quick install applications.  

Contactor 

A contactor is an electromechanical relay designed to carry larger amp loads than a standard control relay.  

Control Loop 

A control loop is the relationship between a sensor, controller, and controlled device used to maintain a setpoint smoothly and accurately. BAS controllers use PID loops to control temperature, pressure, flow, and other continuously changing conditions.  

Control Point 

A control point is an individual data value or command in a building automation system, such as a temperature reading, fan status, valve command, alarm condition, or occupancy signal. 

Controller 

In a building automation or management system, a controller is made up of software and hardware that automatically manage and control the building’s systems, like HVAC and lighting. 

Cooling Tower 

A cooling tower rejects heat from a building by transferring heat from condenser water to the outdoor air. Cooling towers are commonly used with water-cooled chiller plants in larger commercial buildings.  

CO2 Sensor 

A CO2 sensor measures the concentration of carbon dioxide in indoor air. In BAS applications, CO2 sensors are commonly used for demand control ventilation and indoor air quality monitoring.  

Current Switch 

A current switch is a specialty sensor that monitors an electrical current as it runs through a wire. Current switches have a binary on/off function, turning off when they sense that an electrical current crosses a specific threshold.  

Current Transducer 

Current transducers measure AC or DC electrical current and convert it into a standardized, proportional output signal suitable for lower-power devices such as control panels or PLCs. 

Current Transformer 

A current transformer (CT) is an electrical instrument transformer used to measure high alternating current by safely reducing it to a lower, measurable value. CTs allow meters, controllers, and monitoring equipment to read current without directly handling the full load current.  

Current Transmitter 

A current transmitter is a type of current transducer that converts electrical currents but includes specialized features that allow the signal to be transmitted over long distances. 

Damper 

A damper is an adjustable plate or blade used to control airflow inside ductwork or air-handling equipment. In HVAC and building automation, dampers are used to regulate outside air, return air, exhaust air, smoke control, and zone airflow - helping control temperatures and maintain indoor air quality. 

Data Visualization 

Data visualization is the process of taking complex data and/or data from different sources and converting it into a clear visual format so that it is easy to understand. In building automation and management systems, data visualization tools help us monitor, manage, and optimize a wide range of systems, like electrical, security, and HVAC in a simple, centralized format. 

DC Power Supply 

A DC power supply is a device that converts incoming electrical power into stable direct current (DC) at the voltage required by controls, sensors, relays, and other low-voltage devices. 

Dehumidifier 

In an HVAC system, a dehumidifier removes moisture from the air in a space. While standard HVAC systems act as dehumidifiers, removing moisture while cooling a space, there are further specialized dehumidifiers that can enhance an HVAC system and improve tenantcomfort and health. 

Demand Control Ventilation (DCV) 

Demand control ventilation is a control strategy that adjusts outdoor air ventilation based on occupancy or indoor air quality conditions. CO2 sensors are commonly used to estimate occupancy and reduce unnecessary ventilation energy use.  

Differential Pressure 

Differential pressure is the difference in pressure between two points. Building systems use differential pressure to monitor filters, prove airflow or water flow, control pumps, measure room pressurization, and regulate duct static pressure.  

DIN Rail 

DIN rails are metal rails or strips that are used to mount, organize, and secure devices in an electrical or control panel. 

Direct Digital Control (DDC) 

Direct digital control (DDC) refers specifically to building control methodology, which uses microprocessor-based controllers to automate and optimize building systems, often replacing older, pneumatic devices.  

Dry Contact 

A dry contact is an electrical contact that does not supply its own voltage. It simply opens or closes a circuit supplied by another device, making it useful for status, alarm, enable, and interlock signals. 

Dry Differential Pressure Switch 

Dry differential pressure switches measure the pressure difference between two points of air and trigger an electrical switch if the difference exceeds a predefined limit. 

Dry Differential Pressure Transmitter 

Dry differential pressure transmitters provide continuous, real-time measurement of the pressure difference between two points and are used exclusively for monitoring air or other non-corrosive gases. 

Duct Static Pressure Sensor 

A duct static pressure sensor measures air pressure inside ductwork and sends a signal to a controller. In VAV systems, this signal is often used to control fan speed through a variable frequency drive. 

Economizer 

An economizer is an HVAC component or control sequence that improves energy efficiency by using suitable outdoor air to provide free cooling. When outdoor temperature and humidity conditions are favorable, the economizer opens outside-air dampers and reduces the need for mechanical cooling.  

Electric Actuator  

An electric actuator converts electrical energy into controlled mechanical motion. In building automation, electric actuators are primarily used to position valves and dampers in response to a control signal.  

Electrical Box 

An electrical box is an enclosed panel that houses and protects building electrical components, such as wiring, from external elements and organizes them to help prevent hazards like electrical fires or short circuits. 

Electrical Panel 

While the terms electrical panel and electrical box are often used interchangeably, the electrical panel is the internal network of devices and wiring, and the electrical box is the protective enclosure that houses it. 

Electrical System 

An electrical system is an integrated network of components that receives electrical power and safely distributes it to building elements like lighting, outlets, and HVAC. 

Electronic Fail Safe Damper Actuator 

An electronic fail safe damper actuator is designed to drive a damper to a predefined fail position – typically open or closed – when power is interrupted. Instead of relying on a mechanical spring, many electronic  fail safe actuators use stored electrical energy to complete the fail safe movement.  

Electronic Fail Safe Valve Actuator 

Electronic fail safe valve actuators are motorized devices that are designed to drive a valve to a “fail” position – typically open or closed – when power supply is lost or interrupted. 

Electronic Fail Safe Valve Assembly 

An electronic fail safe valve assembly includes a valve and an electronic fail safe actuator. The actuator stores energy, typically a built-in capacitor, and uses that energy to drive the valve to its fail-safe position if power is lost.  

Emergency Station  

In a building system, an emergency station is a designated location used to report an emergency—such as a fire pull station or security button—and to initiate an appropriate response, such as a building lockdown or activation of fire alarms. 

Enclosed Relay 

An enclosed relay is packaged inside a protective enclosure with the required mounting hardware and wiring terminations. Enclosed relays simplify installation and protect the relay in HVAC, BAS, and light industrial control applications. 

Enclosure 

In building automation, an enclosure refers to any protective element that houses, secures, or organizes elements of a system, like electrical or wiring.  

Energy Efficiency 

At its core, energy efficiency means using less energy to perform the same task and achieve the same result. It is a key consideration when selecting products for an HVAC system or BAS in large-scale commercial buildings and spaces, as it can significantly reduce operating costs.  

Energy Valve 

An energy valve is an intelligent, specialized valve that allows for precise flow control and fine-tuning to match changing demand conditions. Because energy valves can dynamically adjust flow rates so precisely, they can also help optimize HVAC systems and improve energy efficiency.  

Enthalpy 

Enthalpy is the combination of temperature and humidity in a space. In HVAC, enthalpy helps determine whether oudoor air can be used efficiently for cooling and how much energy is required to condition a space. 

Expansion Tank 

An expansion tank is a safety device attached to a boiler system that absorbs any excess pressure caused by the water in the boiler heating up and expanding. Expansion tanks prevent high pressure, boiler leaks, and damage to the boiler system.  

Fail Safe Position 

A fail safe position is the position a valve, damper, or controlled device moves to when power, control signal, or air pressure is lost. The proper fail position is selected based on equipment protection, comfort, and life-safety requirements.  

Fan Coil Unit (FCU) 

A fan coil unit, or FCU, is a terminal HVAC device that uses a fan and a heating or cooling coil to condition air for a specific room or zone. FCUs are commonly connected to chilled water, hot water, or refrigerant systems.  

Fan Control Center 

A fan control center (or fan center) is an HVAC component that combines a 24V step-down transformer and a switching relay into a single, compact unit. It acts as a central junction and control switch to safely manage blower motors and auxiliary equipment in heating and cooling systems. 

Fastener 

Fasteners are pieces of hardware that joins two elements of a structure or system together 

Fire & Smoke Actuators 

Fire and smoke actuators are motorized safety devices used in HVAC systems to automatically open and close air duct dampers to prevent smoke, flames, or hot gases from spreading, damaging property, or causing harm to building tenants in the event of a fire. 

Fire Safety System 

Fire safety systems are made up of hardware and software components that allow building systems and managers to watch for and respond to fires quickly and effectively. 

Fitting 

Fittings are very similar to fastenings, with a subtle distinction. A fitting connects parts – like pipes – while a fastener holds them together. 

Flame Rod 

A flame rod is a flame-sensing electrode used in gas burner systems to prove flame by detecting a small electrical current through the flame. If the flame is not proven, the burner controls or flame safeguard shut the system down to prevent unsafe fuel release.  

Flame Sensor 

A flame sensor is a critical component of a fire safety or management system, responsible for detecting the presence of a flame and initiating the appropriate response. 

Flanged Valve 

A flanged valve has a flange at each end of its body, which is bolted to the corresponding pipe flanges with a gasket in between to create a tight, leak‑proof seal. Flanged valves are typically selected because they are versatile, durable, and easy to maintain or replace. 

Flow 

In building automation, “flow” is a general term that refers to the movement of liquids (such as water or refrigerant), vapor, or air. Flow is measured and regulated by many different components to help maintain and optimize things like temperature and air quality in a building. 

Flowmeter 

A flowmeter is an instrument used to measure the mass, volume, or speed of the flow of liquid, vapor, or gas that is moving through a duct or pipe.  

Flow Switch 

A flow switch monitors the flow of liquid, vapor, or gas in a duct or pipe and turns equipment on or off if it detects abnormalities in flow.  

Gas Flow Meter 

Gas flow meters are a specialized type of flowmeter that measures the mass or flow of gas moving through ducts or pipes. 

Gas Regulator 

A gas regulator is a valve that is used to control or reduce the pressure of a gas from a high-pressure supply source to a lower, ideal pressure for specific applications. 

Gas Sensor 

A gas sensor is an instrument that detects gas in certain environments and may be programmed to react or respond to the presence of gas. 

Gas Valve 

A gas valve controls the flow of gas to combustion equipment such as furnaces, boilers, and burners. Gas valves may be operated by an electric actuator, solenoid, or fluid-power actuator depending on the system design and safety requirements. 

Gateway 

In a building automation system, a gateway is a “translator” that connects systems or devices with different communication protocols so that they can speak to each other and work together.  

General Purpose Relay 

General purpose relays are electrical switches that are designed to work in a broad range of applications. A general purpose relay uses a low power control signal to turn higher-power electrical circuits on or off. 

Globe Valve 

A globe valve is a linear motion valve, comprised of a movable plug or disc that fits into a seat that is enclosed in a spherical body. Globe valves are primarily used to regulate the flow of liquids by moving the plug up or down and are excellent for precise flow control.  

Hand Tool 

Hand tools are instruments that are operated by hand. They may be solely "powered" by a person, like a screwdriver or wrench, or simply a handheld device that requires manual help, like a digital manometer or thermo-hygrometer. 

Heat Sequencer 

A heat sequencer is a specialized time-delay relay that staggers the activation of elements in an HVAC system, ensuring that the system runs safely and efficiently.  

Heating Control System 

A heating control system is comprised of hardware and software components that optimize and automate key functions for heating a building or space. 

Hot Water System 

A hot water system circulates heated water through piping, coils, radiators, or terminal units to provide space heating. In commercial buildings, hot water systems are often served by boilers and controlled through pumps, valves, and temperature sensors.  

Humidity Controller 

A humidity controller, or humidistat, is a device that monitors the amount of water vapor (humidity) in the air and, when it detects excess moisture, signals the HVAC system or dehumidifier to begin removing moisture from the air. 

HVAC 

HVAC stands for Heating, Ventilation, and Air Conditioning. HVAC systems consist of various components that regulate heating, cooling, and indoor air quality. They are also commonly integrated into building automation systems (BAS). 

Hydronic  

Hydronic refers to heating or cooling systems that transfer heat by circulating fluid through a closed system of pipes. 

Hydronic Valve 

Hydronic valves regulate, direct, and control the flow of liquids – typically water or refrigerant – in a heating or cooling system. A hydronic valve works by opening, closing, or partially obstructing liquid so that it flows efficiently and continuously, or to a specific zone. 

I/O Module 

An I/O (input/output) module helps bridge the gap between a central processor and peripheral devices – they are added to controllers that require more inputs and outputs than what comes standard on a control. 

Ignitor 

A furnace ignitor is an electronic component in modern heating systems that ignites fuel and initiates the heating or combustion process. 

Ignition Transformer 

An ignition transformer is an electrical device that steps voltage up to create the high-voltage spark needed to ignite fuel in a burner or furnace. It is commonly used in combustion systems that require spark ignition for safe startup. 

Indicator Light 

Indicator lights quickly showcase the status or condition of equipment and processes. For example, a green indicator light may show that a process is complete, or a piece of equipment is working as expected, while a red light might indicate that there is an emergency leak or a faulty piece of equipment in a building system.    

Indoor Air Quality (IAQ) 

Indoor air quality (IAQ) is the condition of the air inside and around buildings, and is determined by the levels of humidity, temperature, ventilation, and airborne pollutants. Poor IAQ impacts building tenants’ health, comfort, and safety, making it essential to monitor and regulate in commercial buildings and spaces. 

IP Rating 

An IP rating, or ingress protection rating, is an international enclosure rating system that indicates how well an enclosure protects electrical equipment from solids and liquids. The first digit describes protection against dust or solid objects, while the second digit describes protection against water. 

IR Flame Detector 

An IR flame detector is a flame-sensing device that detects infrared radiation generated by a flame. IR detectors are used in combustion safety systems and are often selected where the application requires reliable flame detection under specific fuel, burner, or environmental conditions.  

JACE 

JACE stands for Java Application Control Engine. In building automation applications, it is a powerful piece of hardware that powers and controls building systems. The JACE is a supervisory controller that allows users to connect to the field devices and user interface.  

Junction Box 

A junction box is an enclosure designed specifically to safely connect or splice multiple electrical wires together. 

Leak Detector 

A leak detector senses the presence of an unwanted fluid or gas and can alert a controller, alarm system, or building automation system. In building systems, leak detectors may be used for water, refrigerant gas, combustible gas, and other monitored substances depending on the application.  

Level Transmitter 

A level transmitter is an instrument that continuously measures the level of a medium in a vessel and then converts the measurement into an electrical signal that is sent to the central controller for monitoring. 

Light Level Sensor 

Light level sensors measure the amount of light in a space and convert it into an electrical signal that is sent to a transmitter, which amplifies the signal and sends it to the larger system controls. 

Lighting 

In building automation and management, lighting refers simply to the lighting systems within a building. These systems can be integrated into a BAS so that lights turn on or off automatically based on occupancy, improving energy efficiency for the building.  

Liquid Cooling 

Liquid cooling is a process that circulates fluid (typically water or a specialized coolant) through pipes, tubing, and coils to a block mounted on the component, where it absorbs heat before being continuously recirculated to keep the system cool. 

Low Temperature Detector 

A low temperature detector or freezestat is a device that can detect extremely low and hazardous temperatures. They are commonly used to open valves and initiate flow so that standing water doesn’t freeze and break pipes or fittings. 

Manifold 

A manifold is a central junction with multiple ports that helps control the distribution of water, air, and other fluids.  

Manifold Gauge 

A manifold gauge, often referred to as refrigeration testing equipment, is a diagnostic and service tool that is used to measure, monitor, and regulate pressure in an HVAC system. 

Manifold Hose 

Manifold hoses are color-coded tubes that connect the manifold gauge diagnostic tool to the system that is being worked on, like an air conditioner. 

Mixed Air 

Mixed air is the combination of outside air and return air before it passes through an air-handling unit. Mixed air temperature is often monitored to support economizer operation and freeze protection.  

Modbus 

Modbus is an open communication protocol used to exchange data between electronic devices. In building automation, Modbus is often used to integrate meters, variable frequency drives, boilers, chillers, generators, and other equipment into a BAS. 

Motor Starter 

A motor starter is an electrical device that safely starts and stops the motor(s) found in HVAC systems. They have “overloads” that act as fuses to prevent overheating. 

NEMA Rating 

NEMA is the National Electrical Manufacturers Association. A NEMA rating is a standard established by the association that defines the types of environments an electrical enclosure can be used in, based on the enclosure’s capability to withstand certain environmental conditions. For example, NEMA 1: Designed for indoor, dry, clean areas. It primarily protects personnel from touching live parts and keeps falling dirt or debris out of the enclosure. NEMA 4: Designed for indoor or outdoor use. It is completely watertight and dust-tight. It protects against windblown dust, rain, splashing water, and even direct hose-directed washdowns.  

Network I/O Module 

Network I/O modules are a specific type of I/O module that can work remotely, transmitting data over a communication protocol, like Ethernet or BACnet. 

Network Switch 

A network switch is a data-networking device that connects multiple wired devices on the same network and directs traffic between them. In building automation, network switches connect controllers, supervisory devices, workstations, and IP-based equipment so BAS data can move reliably across the control network. 

Niagara Framework 

The Niagara Framework is a software platform used to connect, normalize, and manage data from different building systems and protocols. It is commonly used in supervisory controllers and building automation integrations.  

Non-Spring Return Damper Actuator 

Non-spring return damper actuators are devices that “fail in place" in the event of a power failure. Unlike spring-return damper actuators, they do not have a spring to snap the damper back to its “fail-safe” position.  

Non-Spring Return Valve Actuator 

Unlike pring return valve actuators, a non-spring return valve actuator does not rely on a spring (or capacitor) to drive the valve to its default position. The valve remains in its current position during a loss of power. 

Non-Spring Return Valve Assembly 

A non-spring return valve assembly is a broad system that includes a non-spring return actuator, used to keep valves and dampers in their current position in the event of a power failure, rather than returning to a fail safe position. 

NOx Sensor 

An NOx sensor measures nitrogen oxides produced during combustion. In HVAC and boiler applications, NOx measurement may be used for emissions monitoring, combustion tuning, and compliance in areas with stricter air-quality requirements. 

Occupancy Sensor 

An occupancy sensor detects whether people are present in a space. Building automation systems use occupancy data to adjust HVAC, lighting, ventilation, security, and energy-saving schedules. 

Occupied Schedule 

An occupied schedule tells a BAS when a building or zone is expected to be in use. During occupied periods, the system typically maintains comfort setpoints and ventilation levels. During unoccupied periods, it may relax setpoints to save energy.  

Outside Air 

Outside air is fresh outdoor air brought into an HVAC system for ventilation, economizer cooling, pressurization, or indoor air quality control.  

Override 

An override is a temporary manual command that changes the normal automatic operation of a device or control point. Overrides are useful for testing and troubleshooting but should be monitored so equipment does not remain out of normal control longer than necessary.  

PID Control 

PID control is a control method that uses proportional, integral, and derivative calculations to maintain a setpoint smoothly and accurately.  

Pilot Light 

A pilot light is a small, continuously running flame that serves as an ignition source for a burner, helping power appliances like furnaces.  

Pilot Relay 

Pilot relays are small, low-power devices that act as an electrical buffer between delicate pieces of equipment, like PLCs, and high-powered equipment like motor starters, helping prevent electrical overload and other potential electrical hazards. 

Pipe-Mounted Sensor 

A pipe-mounted sensor is a device that is attached to the outside of a pipe to monitor the temperature, pressure, or flow rate of the liquid within the pipe without requiring extensive or invasive installation. 

Pipe Strap-On 

A pipe strap-on is a specific type of pipe-mounted sensor that is simply wrapped or clamped directly around a pipe. Their simple installation makes them a great choice for retrofits and quick installation.  

Plumbing Circuit 

A plumbing circuit is a defined loop or branch of piping that moves water or another fluid through part of a plumbing or hydronic system. In building systems, plumbing circuits may serve fixtures, heating zones, cooling loops, pumps, coils, or equipment that requires controlled fluid flow.  

Pneumatic 

In a building system, pneumatic refers to the use of pressurized air, not electrical voltage, to power the system. 

Pneumatic Controller 

A pneumatic controller is a mechanical device that measures conditions like pressure or temperature and converts those measurements into air pressure signals that power other elements, such as valves or dampers, to achieve a desired output. 

Pneumatic Damper Actuator 

A pneumatic damper actuator is a piece of equipment that leverages pressurized air, perhaps from a pneumatic controller, and uses it to move a damper into a specific position. 

Pneumatic Electric Switch 

A pneumatic electric switch bridges pneumatic systems and electrical systems, converting air pressure into an electrical signal that can start, stop, or regulate circuits and power equipment. 

Pneumatic Relay 

Pneumatic relays work very similarly to pilot relays, creating a buffer between low-power and high-power equipment. However, unlike a pilot relay, a pneumatic relay is used to manage the flow of pressurized air instead of electricity.  

Pneumatic Temperature Sensor 

A pneumatic temperature sensor is a device that measures the temperature and then converts the measurement into a pressurized air signal.  

Pneumatic Thermostat 

A pneumatic thermostat controls heating and cooling in an HVAC system by adjusting air pressure in a control line, which signals components like dampers and valves to open or close, changing the temperature to meet the desired set point.  

Pneumatic Valve Actuator 

Pneumatic valve actuators use pressurized air to power the movement of a valve into a specific position, such as open or closed. 

Potentiometers 

A potentiometer is a manually adjustable variable resistor with three terminals and a movable component like a dial or lever (often called a wiper), most used to control voltage and vary resistance in an electrical circuit.  

Power Meter 

Power meters monitor the energy usage in a building, providing key insights on power consumption, demand, and quality.  

Power Monitoring 

Power monitoring is the process of tracking and analyzing power usage in a specific space, such as a commercial building, to ensure that systems are running efficiently, meeting demand, and keeping building tenants comfortable. 

Power Relay 

A power relay is a robust relay built to withstand heavy electrical currents, protecting low-power devices like controllers from high-powered circuits by acting as a buffer between the two and safely turning high-power circuits on or off.  

Power Supply 

A power supply, sometimes called a power supply unit (PSU), converts electrical power from a source into a specific voltage, frequency, and current needed to power a device. 

Pre-Built Control Panel 

Pre-built (or pre-fabricated) control panels are ready-to-install enclosures that contain pre-wired and assembled components like controllers, motor starters, and power supplies. Pre-built control panels are typically available in a variety of sizes to meet specific needs and are ideal for simple installations and budget-conscious projects. 

Pressure Controller  

A pressure controller is an automated device that regulates pressure levels in a system, helping it run efficiently and making adjustments to ensure precise pressure control for specific environmental needs. 

Pressure Gauge 

Pressure gauges are devices that measure the internal pressure of an element and visually display the measurement with an analog pointer or a digital interface so that the pressure levels can be monitored and managed. 

Pressure Independent Valve 

Pressure independent valves are used to regulate the flow of air or water in a building’s cooling and heating systems, maintaining a constant flow rate regardless of any pressure fluctuations and ensuring precise temperature control. 

Pressure Regulating Valve 

Pressure regulating valves are used to decrease the incoming pressure from a main supply to a safe, usable level for other systems. 

Pressure Sensor 

A pressure sensor is a device that measures pressure and converts it into an electrical signal. 

Pressure Switch 

A pressure switch is an electronic or mechanical device that is activated when a specific pressure is reached. 

Pressure Transducer 

Pressure transducers are electromechanical devices that measure pressure levels with incredible accuracy and convert the input into a usable electrical output signal. 

Preventative Maintenance 

Preventative maintenance is regularly scheduled inspection and repair of system equipment to ensure things are performing as expected and to catch any potential problems that could lead to system failures.  

Programmable Controller 

A programmable controller is a type of controller that allows users to freely program automation and controls, unlike a configurable controller that comes with preset choices for control parameters.  

Programmable Logic Controller (PLC) 

A programmable logic controller (PLC) is a specific type of programmable controller. PLCs are typically used for heavy-duty machinery applications and can be programmed freely to automate, control, and monitor large-scale industrial processes and systems.  

Pull Box 

Pull boxes are a type of enclosure installed along long or complex conduit runs to help pull, route, and manage cables without damaging the wires or having to make splices. 

Push Button 

A push button is an electromechanical switch that closes or opens a circuit, powering another component or machine. 

Relay 

In building systems, relays act as electrically operated switches, allowing low-power signals from smaller, delicate devices like thermostats or controllers to safely drive an action from a larger, high-power device, like a motor starter or pump. 

Relay Socket 

Relay sockets are critical interfaces that hold relays in place and provide electrical connections that a relay needs to function.   

Remote Probe 

A remote probe is a sensor that is attached to a long cable and measures conditions like temperature, humidity, or pressure in hard-to-access spaces or areas. 

Remote Sensor 

Remote sensors are devices that measure conditions like temperature and humidity from a distance and send real-time data back to central systems, so adjustments can be made. 

Repeater 

A repeater is a device that takes signals, amplifies or cleans them, and retransmits them, making them stronger. This allows building automation and management system components to communicate over large distances or around physical obstacles, helping ensure no data is lost. 

Return Air 

Return air is air pulled from occupied spaces back to HVAC equipment so it can be filtered, reheated, recooled, exhausted, or mixed with outside air.  

Rooftop Unit (RTU) 

A rooftop unit, or RTU, is a packaged HVAC unit installed on the roof of a building. RTUs typically combine heating, cooling, ventilation, economizer dampers, fans, filters, and controls in a single outdoor unit.  

Room Humidity 

Room humidity is the amount of moisture (water vapor) present in the air within a confined space. Room humidity can be measured as relative humidity (RH), which is the measure of water vapor relative to the temperature of the air, expressed as a percentage. It can also be measured as absolute humidity, which is the total amount of water vapor contained in a specific volume of air regardless of the room’s temperature, expressed grams per cubic meter. 

Room Pressure Monitor 

A room pressure monitor is a safety device that measures the differential pressure between two rooms in critical environments, like a hospital clean room and its surroundings. Room pressure monitors control airflow, helping contain contaminants and keeping sterile areas protected. 

Router 

Routers act as a hub for digital traffic, connecting devices to the internet, and ensuring information reaches the right destination. In a building system, routers are essential for connecting devices and bridging the gap between different communication protocols, allowing system components to talk to each other. 

Selector Switch 

A selector switch is a manually operated device that opens, closes, or redirects electrical circuits, allowing the operator to choose a machine state from a predefined set. 

Sequence of Operations 

A sequence of operations is the written description of how a building system should operate under different conditions. It explains when equipment starts, stops, modulates, alarms, locks out, or changes modes. 

Setpoint 

A setpoint is a target value a control system is trying to maintain, such as room temperature, duct pressure, humidity, or water temperature. Controllers compare actual conditions to the setpoint and adjust equipment to reduce the difference.  

Smoke Detector 

A smoke detector is a device that can sense small particles in the air in a closed space, alerting tenants and control systems once particles reach a dangerous level. 

Solenoid Valve 

Solenoid valves are electromechanical devices used to control the flow of liquids or gases. A solenoid is a coil that is electrically energized and either attracts or repels a plunger, changing the position of a valve body and controlling flow direction and volume. When the solenoid is de-energized, the plunger and valve body return to their original positions.  

SOx Sensor 

An SOx sensor measures sulfur oxides produced during combustion, especially where fuel sulfur content or emissions standards are a concern. SOx measurement helps support emissions monitoring and environmental compliance in applicable boiler, burner, and industrial combustion systems.  

Spring Return Damper Actuator 

A spring return damper actuator is a device that uses compressed air, liquid, or electricity to set off internal springs or a capacitor, releasing stored energy and driving a damper to a fail safe position in the event of power failure or pressure loss. 

Spring Return Valve Actuator 

Spring return valve actuators use compressed air, liquid, or electricity to set off internal springs, releasing stored energy and driving valves to a fail safe position in the event of power failure or pressure loss. 

Spring Return Valve Assembly 

A spring return valve assembly is a group of components, including a spring return actuator, which work together to return valves to fail safe positions in the event of power failures, pressure loss, or emergency shutdowns, ensuring that systems are not damaged. 

Static Pressure 

Static pressure is the air pressure inside ductwork that a fan must overcome to move air through filters, coils, dampers, ducts, and diffusers. Duct static pressure is commonly controlled in VAV systems to maintain proper airflow.  

Steam Valve 

Steam valves are specialized valves that control the flow, pressure, and temperature of steam in a system and are built to withstand steam’s high temperatures and pressure 

Supervisory Controller 

A supervisory controller is a higher-level control device that coordinates lower-level controllers, executes control logic, and often provides network communication and data services as the engine of the BAS system. 

Supply Air 

Supply air is conditioned air delivered from HVAC equipment into a room, zone, or building area. Supply air temperature and airflow are commonly monitored and controlled by building automation systems.  

Surge Protector 

Surge protectors protect electrical equipment from power surges or spikes by regulating the electrical current that flows to devices and blocking or diverting excess voltage to the ground. 

Switch 

A switch is a device that opens or closes an electrical circuit. Closing the circuit allows a current to flow; opening the circuit interrupts the current flow.  

System Integrator 

A system integrator designs, programs, installs, and connects building automation systems so equipment, controllers, software, and networks operate together. Integrators often bridge HVAC, electrical, security, lighting, and IT requirements. 

Temperature Controller 

Temperature controllers receive data from temperature sensors, compare that data to a predetermined setpoint, and then send an output signal to control elements like fans and heaters, adjusting the temperature in a room automatically. 

Temperature Cutout 

A temperature cutout is an electrical safety device that stops the flow of electrical currents when it senses a machine or appliance has exceeded safe temperatures. 

Temperature Gauge 

Temperature gauges measure the temperature of building systems and environments and display the temperature so that it can be monitored and regulated.  

Temperature Sensor 

A temperature sensor is the specific device that measures the temperature of an element, such as a liquid or gas, in a system, converts the measurement into an electrical signal, and sends it to other temperature controls. 

Temperature Transmitter 

Temperature transmitters receive the signal from temperature sensors and amplify it so that it can be sent over long distances to centralized building control systems, which automatically adjust temperatures as needed. 

Terminal Block 

A terminal block is a modular, insulated connector that secures two or more wires together without having to cut or splice them. 

Test Equipment 

Test equipment is a range of tools and instruments that are used to test the performance, safety, and efficiency of devices and components in a building system and provide information on potential problems.  

Thermal Management Unit 

A thermal management unit (TMU) is a system that controls temperatures using technology and manages heat generation, transfer, and dispersal in a system, ensuring that it runs efficiently and safely.  

Thermostat 

Thermostats are essential elements of temperature control systems that monitor and regulate temperature in a space by automatically turning heating and cooling systems on or off.  

Thermowell 

A thermowell is a protective sleeve installed into a pipe, tank, or vessel, so a temperature sensor can measure a liquid or gas while remaining protected from pressure, flow, and corrosion.  

Third Party Network Driver 

A third party network driver is a software model that is designed to connect building system components that use different communication protocols, allowing them to communicate, work together, and share consistent data in a centralized hub. 

Time Delay Relay 

Time-delay relays have built-in time delay functions that stagger electrical circuits, activating or deactivating the circuits for a predefined amount of time. 

Transformer 

A transformer is an electrical device that changes one AC voltage to another AC voltage. 

Trend Log 

A trend log is a stored record of BAS data over time, such as temperatures, pressures, valve positions, alarms, or equipment status. Trend logs help technicians troubleshoot issues, verify performance, and identify energy-saving opportunities.  

Tubing 

In a building system, tubing is made of a flexible but durable material, used to distribute elements like liquid or air.  

Uninterruptible Power Supply 

An uninterruptible power supply (UPS) is an electrical device that provides backup power to equipment in the event of a power failure or interruption, ensuring there is no data loss, hardware damage, or user downtime.  

Unitary Controllers 

Unitary controllers are compact, programmable devices used for direct digital control of temperature and energy management functions in a building. 

UV Flame Detector 

A UV flame detector is a flame-sensing device that detects the ultraviolet radiation produced by combustion. UV detectors are commonly used in burner and flame safeguard systems to quickly prove flame or initiate a safety shutdown when flame is not present.  

Valve 

Valves are components that regulate and direct the flow of elements like liquids or gases by opening, closing, or partially opening.  

Variable Frequency Drive (VFD) 

A variable frequency drive (VFD) is an intelligent, electronic device that controls the speed of an AC electric motor by varying the frequency and voltage that is supplied to the motor, ensuring that it runs efficiently. 

VAV Controller 

A variable air volume (VAV) controller is a specialized controller that regulates airflow in different rooms or zones of a building, optimizing HVAC systems for energy efficiency and performance. 

VAV Terminal Box 

Variable air volume (VAV) boxes are localized devices that are used to control and regulate the amount of conditioned air that specific rooms and zones in a building receive, working in tandem with VAV controllers. 

Virtual Point 

A virtual point is a software-based BAS point that is calculated or created in the controller or supervisory software rather than wired directly to a physical device. Virtual points are often used for logic, alarms, averages, or calculated values. 

Wall Plate 

Wall plates are small metal or plastic components that are mounted on walls to protect and organize wiring, or to sense and help regulate conditions like temperature and humidity in a room. 

Water Flow Meter 

A water flow meter is a specific type of flow meter that measures the speed, amount, or volume of water moving through pipes in a building system. 

Water Flow Switch 

Water flow switches monitor the movement of water through a pipe and then convert that movement into an electrical signal when the flow reaches, exceeds, or drops below a set point. Water flow switches are commonly used to prove flow, protect equipment, or trigger an action or alarm.  

Wet Differential Pressure Switch 

Wet differential pressure switches measure the pressure difference between two “points” of liquid within a system, and trigger an electrical switch if the difference exceeds a predefined limit. 

Wet Differential Pressure Transmitter 

A wet differential pressure transmitter measures the pressure difference between two liquid points, converting the difference into an electrical signal and transmitting it to other components in a control system so they can automatically perform certain functions.  

Wire Connector 

Wire connectors are used to safely join two or more electrical wires together. 

Wire Duct 

Wire ducts are plastic or metal troughs that are used to organize, protect, and route wires and cables.  

Wireless Sensors 

In a building automation system, a wireless sensor is a component that monitors environmental conditions and sends data to controls via radio frequencies. Wireless sensors are a cost-effective and flexible solution for automation because they do not have wires or other components that have to be installed around the physical obstacles of a building.  

Zone Dampers 

Zone (or zoning) dampers are like gates inside HVAC ductwork, automatically opening or closing to control airflow to specific zones in a building, controlling temperatures and improving energy efficiency.  

Zone Valves 

A zone valve is a control device that fully or partially opens and closes, modulating water flow to different zones in a building for specific temperature control and energy efficiency. 

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