A Glossary of the Top 25 MEP Terms Engineers Use

Mechanical, Electrical, and Plumbing (MEP) engineers design the systems that make buildings function every day. They keep air moving, power flowing, and water running safely and efficiently. Behind every comfortable office, hospital, school, or manufacturing facility, MEP professionals coordinate complex infrastructure that most occupants never see. To collaborate effectively and avoid costly mistakes, they rely on clear, precise technical language.

Air Handling Unit (AHU): A central heating, ventilation, and air conditioning (HVAC) component that conditions and circulates air through a building using fans, heating and cooling coils, filters, and dampers.

British Thermal Unit (BTU): A unit of heat energy commonly used to measure heating or cooling capacity in HVAC systems.

Building Automation System (BAS): A centralized control system that monitors and manages HVAC, lighting, security, and other building systems.

Chiller: A machine that removes heat from liquid, typically water, to provide cooling for air conditioning or industrial processes.

Cooling Tower: Equipment that dissipates heat from a water-cooled system by transferring it to the atmosphere.

Cubic Feet per Minute (CFM): A measurement of airflow volume used to size ductwork and ventilation systems.

Ductwork: The network of channels that distribute conditioned air throughout a building.

Electrical Load: The amount of power consumed by equipment or systems connected to an electrical circuit.

Emergency Power System (EPS): Backup power infrastructure, such as generators or batteries, that supplies electricity during outages.

Fire Protection System: Integrated systems such as sprinklers, standpipes, and alarms designed to detect and suppress fires.

Ground Fault Circuit Interrupter (GFCI): A safety device that shuts off electrical power when it detects ground faults to prevent shock.

Heat Exchanger: A device that transfers heat between two fluids without mixing them.

HVAC (Heating, Ventilation, and Air Conditioning): The combined systems responsible for thermal comfort and indoor air quality.

Illuminance: The amount of light that falls on a surface, typically measured in lux or foot-candles.

Load Calculation: The process of determining heating, cooling, and electrical demands for a building.

Manifold: A pipe or chamber that distributes fluids to multiple outlets in plumbing or hydronic systems.

Mechanical Room: A dedicated space housing major building equipment such as boilers, pumps, and electrical panels.

Panelboard: An electrical distribution board that divides power into branch circuits and provides circuit protection.

Pump Head: The height a pump can raise fluid, reflecting its pressure capability.

Revit MEP: A Building Information Modeling (BIM) software application used to design, coordinate, and model MEP systems within a building.

Short Circuit: An unintended electrical connection that allows excessive current to flow.

Static Pressure: The resistance to airflow within ducts and ventilation systems.

Switchgear: Electrical equipment that controls, protects, and isolates power systems.

Variable Air Volume (VAV): An HVAC system that adjusts airflow to maintain temperature while conserving energy.

Water Hammer: A pressure surge in plumbing systems caused by sudden changes in fluid flow.

Additional Resources

• Plumbing Terms
• What is Engineering?
• Basic HVAC/R Terminology
• What is Mechanical Engineering?
• Understanding Electrical Terms (PDF)
• What is Electrical Engineering?
• Plumbing Glossary
• What Electrical and Electronics Engineers Do
• Learn More About Electrical Engineering
• Plumbing Dictionary (PDF)
• What Do Mechanical Engineers Do?
• What is a Plumbing Engineer? (PDF)
• Glossary of Engineering Terms
• What is Engineering?