In the construction and building sector, MEP (Abbreviation of Mechanical, Electrical, and Plumbing) plays a crucial role in ensuring any structure’s functionality, safety, and comfort.
Within the MEP industry, countless abbreviations and acronyms are used daily, so it is essential for professionals, students, and homeowners to understand their meanings.
This blog dives into the most common MEP abbreviations, particularly in HVAC (Heating, Ventilation, and Air Conditioning), mechanical systems, electrical components, and plumbing networks.
Whether you’re a seasoned professional or just starting to explore the field, this guide will help you navigate the language of MEP with confidence and clarity.
| A | |
| AAV | Automatic Air Vent |
| AC | Air Conditioning |
| AC | Alternate Current |
| abs. | Absolute |
| ACD | Automatic Control Damper |
| AD | Access Door |
| ADC | Air Diffusion Council |
| ADP | Apparatus Dew Point |
| ADPI | Air Diffusion Performance Index |
| AF | Air Foil |
| AFD | Adjustable Frequency Drive |
| AFF | Above Finished Floor |
| AFG | Above Finished Grade |
| AHJ | Authority Having Jurisdiction |
| AHU | Air Handling Unit |
| ACCU | Air Cooled Condensing Unit |
| ACPH | Air Change Per Hour |
| AFD | Air Flow Diagram |
| AI | Analog Input |
| AISC | American Institute of Steel Construction |
| ALARP | As Low As Reasonably Possible |
| AMCA | Air Movement and Control Association Inc. |
| ANSI | American National Standards Institute |
| AO | Analog Output |
| AP | Access Panel |
| API | American Petroleum Institute |
| ARI | Air Conditioning and Refrigeration Institute |
| AS | Air Separator |
| ASHRAE | American Society of Heating, Refrigerating, and Air Conditioning Engineers |
| ASME | American Society of Mechanical Engineers |
| ASTM | American Society for Testing and Materials |
| ATC | Automatic Temperature Control |
| ATEX | ATmospheres EXplosible |
| ATM | Atmosphere |
| ATU | Air Terminal Unit |
| AUX | Auxiliary |
| AVM | Anti Vibration Mounting |
| AWG | American Wire Gauge |
| AWS | American Welding Society |
| B | |
| BAC | Building Automation and Control |
| BAS | Building Automation System |
| BBD | Boiler Blow Down |
| BC | Backward Curved (Fan blade) |
| BCU | Blower Coil Unit |
| BD | Balcony Drain |
| BDD | Back Draft Damper |
| BEP | Best Efficiency Point |
| BF | Bypass Factor |
| BF | Bag Filter |
| BF | Boiler Feed |
| BHP | Brake Horse Power |
| BI | Backward Included (Fan Blade) |
| BIM | Building Information Model |
| BMS | Building Management System |
| BOD | Bottom of Duct |
| BOE | Bottom of Equipment |
| BOM | Bill of Material |
| BOP | Bottom of Pipe |
| BOQ | Bill of Quantity |
| BOSIET | Basic Offshore Safety Induction and Emergency Training |
| BP | Booster Pump |
| BP | Back Pressure |
| BS | British Standard |
| BSP | British Standard Pipe (thread) |
| BTU | British Thermal Unit |
| BV | Butterfly Valve |
| C | |
| CADD | Computer-aided Design and Drafting |
| CAFS | Compressed Air Foam System |
| CAPEX | CAPital EXpenditure |
| CAV | Constant Air Volume |
| CB | Circuit Breaker |
| CC | Cooling Coil |
| CCP | Coordinated Ceiling Plan |
| CCR | Central Control Room |
| CD | Condensate Drain |
| CDD | Cooling Degree Day |
| CDL | Condensate Drain Line |
| CDP | Condensate Drain Pipe |
| CF | Contact Factor |
| CFC | Chlorofluorocarbon |
| CFD | Computational Fluid Dynamics |
| CFM | Cubic Feet per Minute |
| CFS | Cubic Feet per Second |
| CFU | Chemical Filter Unit |
| CHW | Chilled Water |
| CHWP | Chilled Water Pump |
| CHWR | Chilled Water Return |
| CHWS | Chilled Water Supply |
| CIBSE | Charted Institution of Building Services Engineers |
| CL | Centre Line |
| CL | Cover Level |
| CLF | Cooling Load Factor |
| CMH | Cubic Meter per Hour |
| CO | Clean Out |
| CO | Carbon Monoxide |
| COG | Centre of Gravity |
| COP | Coefficient of Performance |
| COP | Centre of Pipe |
| CPP | Central Processing Platform |
| CPU | Central Processing Unit |
| CT | Cooling Tower |
| CTR | Cost Time Resource |
| CU | Cabin Unit |
| CU | Condensing Unit |
| CUH | Cabin Unit Heater |
| CV | Check Valve |
| CVU | Constant Volume Unit |
| CW | Cold Water |
| C/W | Complete With |
| CWR | Condenser Water Return |
| CWS | Condenser Water Supply |
| D | |
| DBT | Dry Bulb Temperature |
| DB | Distribution Board |
| DC | Direct Current |
| DDC | Direct Digital Control |
| DCS | Distributed Control System |
| DFT | Dry Film Thickness |
| DG | Diesel Generator |
| D&ID | Ducting and Instrumentation Diagram |
| DI | Digital Input |
| DIN | Deutsches Institute Fur Normung (Germany Institute of Normative) |
| DN | Down |
| DNV | Det Norske Veritas |
| DO | Digital Output |
| DOE | Department of Energy |
| DP | Differential Pressure |
| DPT | Differential Pressure Transmitter |
| DPT | Dew Point Temperature |
| DRV | Double Regulating Valve |
| DS | Data Sheet |
| DSA | Double Strength Sheet Glass |
| DWDI | Double Width Double Inlet |
| DX | Direct Expansion |
| E | |
| EAT | Entering Air Temperature |
| EAL | Exhaust Air Louver |
| EC | European Commission |
| EDG | Emergency Diesel Generator |
| EDH | Electric Duct Heater |
| EER | Energy Efficient Ratio |
| EEV | Electronic Expansion Valve |
| EF | Exhaust Fan |
| EMC | Electro Magmatic Compatibility |
| EMS | Energy Management System |
| EN | European Norm |
| EPIC | Engineering, Procurement, Installation and commissioning |
| EPCI | Engineering, Procurement, Construction and Installation |
| ETQ | Engineering Technical Query |
| ETS | Energy Transfer Station |
| ESD | Emergency Shut Down |
| ESDD | Equivalent Salt Deposit Density |
| ESP | External Static Pressure |
| ET | Expansion Tank |
| EU | European Union |
| EWH | Electric Water Heater |
| EWT | Entering Water Temperature |
| EXH | Exhaust |
| F | |
| FA | Fire Alarm |
| FACP | Fire Alarm Control Panel |
| FAS | Fire Alarm System |
| FAHU | Fresh Air Handling Unit |
| FAT | Factory Acceptance Test |
| FC | Flexible Connection |
| FC | Fail Close |
| FC | Forward Curved (Fan Blade) |
| FCO | Floor Clean Out |
| FCU | Fan Coil Unit |
| FD | Floor Drain |
| FD | Fire Damper |
| FEC | Fire Extinguisher Cabinet |
| FEED | Front End Engineering Design |
| FF | Firefighting |
| FFL | Finished Floor Level |
| F&G | Fire and Gas |
| FH | Fire Hydrant |
| FHC | Fire Hose Cabinet |
| FIM | Free Issued Material |
| FM | Flow Meter |
| FM | Facilities Management |
| FMECA | Failure Mode, Effect and Criticality Analysis |
| FMS | Facility Management System |
| FO | Fail Open |
| FPI | Fins per Inch |
| FPM | Feet per Minute |
| FPS | Feet per Second |
| FPSO | Floating Production Storage and Offloading |
| FRP | Fiberglass Reinforced Plastic |
| FS | Flow Switch |
| FSO | Floating Storage Offloading |
| FU | Fixture Unit |
| FW | Feed Water |
| G | |
| GA | General Arrangement |
| GAD | General Arrangement Diagram |
| GI | Galvanized Iron |
| GIS | Gas Insulated Switchgear |
| GMT | Greenwich Mean Time |
| GPM | Gallon per Minute |
| GS | Galvanized Steel |
| GSS | Galvanized Steel Sheet |
| GT | Gas Turbine |
| GT | Gully Trap |
| GUI | Graphical User Interface |
| GV | Gate Valve |
| GWP | Global Warming Potential |
| H | |
| HAP | Hourly Analysis Program |
| HAT | Highest Astronomical Tide |
| HAZID | Hazard Identification |
| HAZOP | Hazard and Operability |
| HB | Hose Bibb |
| HC | Heating Coil |
| HC | Hydrocarbon |
| HCFC | Hydrochlorofluorocarbon |
| HFO | Hydrofluoroolefins |
| HDPE | High Density Poly Ethylene |
| HEPA | High Efficiency Particulate Air |
| HMI | Human Machine Interface |
| HSE | Health, Safety and Environment |
| HP | High Pressure |
| HP | Heat Pump |
| HP | Heat Pipe |
| HRU | Heat Recovery Unit |
| HRW | Heat Recovery Wheel |
| HSEIA | Health, Safety and Environmental Impact Assessment |
| HUET | Helicopter Underwater Escape Training |
| HV | High Voltage |
| HVAC | High Voltage Alternate Current |
| HVCA | Heating and Ventilating Contractors’ Association |
| HVDC | High Voltage Direct Current |
| HW | Hot Water |
| HWR | Hot Water Return |
| HWS | Hot Water Supply |
| HWT | Hot Water Tank |
| I | |
| IAQ | Indoor Air Quality |
| IACS | International Association of Classification Societies |
| ICMS | Integrated Control and Monitoring Station |
| ID | Inner (or Inside) Diameter |
| IDC | Inter Discipline Check |
| IEC | International Electrotechnical Commission |
| IFA | Issued for Approval |
| IFC | Issued for Construction |
| IFI | Issued for Information |
| IG | Inert Gas |
| IL | Invert Level |
| IMO | International Maritime Organization |
| IOM | Installation, Operation and Maintenance (Manual) |
| I/O | Input & Output |
| IP | Internet Protocol |
| IP | Ingress Protection |
| IP | Institute of Petroleum |
| I-P | Inch Pound |
| ITP | Inspection and Test Plan |
| ISA | International Society of Automation |
| ISO | International Organization of Standardization |
| ISHRAE | The Indian Society of Heating, Refrigerating and Air Conditioning Engineers |
| J | |
| JB | Junction Box |
| K | |
| KOM | Kick of Meeting |
| kV | Kilo Volts |
| L | |
| LAN | Local Area Network |
| LAT | Leaving Air Temperature |
| LAT | Lowest Astronomical Tide |
| LAT | Latitude |
| LCP | Local Control Panel |
| LCS | Local Control Station |
| LD | Linear Diffuser |
| LED | Light Emitting Diode |
| LER | Local Equipment Room |
| LL | Low Level |
| LQ | Living Quarters |
| LMTD | Log Mean Temperature Difference |
| LOI | Letter of Intent |
| LOLER | Lifting Operations and Lifting Equipment Regulations |
| LP | Low Pressure |
| LPS | Liter per Second |
| LRA | Locked Rotor Amperage |
| LS | Level Sensor |
| LSD | Linear Slot Diffuser |
| LTI | Lost Time Incident |
| LU | Loading Unit |
| LV | Low Voltage |
| LVD | Low Voltage Directive |
| LVR | Louver |
| LWT | Leaving Water Temperature |
| M | |
| MA | Make-up Air |
| MAT | Mixed Air Temperature |
| MAU | Makeup Air Unit |
| MAX | Maximum |
| MC | Mechanical Completion |
| MCB | Miniature Circuit Breaker |
| MCC | Motor Control Center |
| MCC | Maximum Continuous Current |
| MCCB | Moulded Case Circuit Breaker |
| MCT | Multi Cable Transit |
| MD | Machinery Directive |
| MDB | Main Distribution Board |
| MEP | Mechanical, Electrical and Plumbing |
| MERV | Mean Efficiency Reporting Value |
| MFD | Motorized Fire Damper |
| MH | Manhole |
| MIN | Minimum |
| MTBF | Mean Time Between Failure |
| MTBO | Mean Time Between Overhaul |
| MTTO | Mean Time to Overhaul |
| MTTR | Mean Time To Repair |
| MED | Marine Equipment Directive |
| MEL | Master Equipment List |
| MODU | Mobile Offshore Drilling Unit |
| MOV | Motor Operated Valve |
| MR | Material Requisition |
| MS | Mild Steel |
| MSL | Mean Seal Level |
| MTO | Material Take Off |
| N | |
| N/A | Not Applicable |
| NA | Not Available |
| NACE | National Association of Corrosion Engineers |
| NC | Noise Criteria |
| NC | Normally Closed |
| NDA | Non-Disclosure Agreement |
| NDE | Non-Destructive Examination |
| NEMA | National Electrical Manufacturers Association |
| NEN | Dutch Norm |
| NFPA | National Fire Protection Association |
| NO | Normally Open |
| NoBo | Notified Body |
| NORSOK | Norwegian Offshore Standard |
| NPL | Neutral Pressure Level |
| NPS | Nominal Pipe Size |
| NPSH | Net Positive Suction Head |
| NRD | Non Return Damper |
| NRV | Non Return Value |
| NTS | Not to Scale |
| O | |
| OA | Outside Air |
| OAT | Outside Air Temperature |
| OD | Outside (or Outer) Diameter |
| ODP | Ozone Depletion Potential |
| OF | Overflow |
| OHT | Overhead Tank |
| OPEX | OPerating EXpenditure |
| OSS | Offshore Substation |
| OS&Y | Outside Screw & Yoke |
| P | |
| PAC | Precision Air Conditioning |
| PB | Push Button |
| PCR | Pitch Circle Diameter |
| PCHE | Printed Circuit Heat Exchanger |
| PDAH | Pressure Differential Alarm High |
| PDAL | Pressure Differential Alarm Low |
| PDMS | Plant Design Management System |
| PDP | Positive Displacement Pump |
| PDS | Plant Design System |
| PDS | Pressure Differential Switch |
| PED | Pressure Equipment Directive |
| PEM | Project Engineering Manager |
| PHE | Plate Heat Exchanger |
| P&ID | Piping and Instrumentation Diagram |
| PID | Pre Insulated Duct |
| PF | Pre Filter |
| PF | Power Factor |
| PFP | Passive Fire Protection |
| PG | Pressure Gauge |
| PL | Punch List |
| PL | Packing List |
| PM | Project Manager |
| PO | Purchase Order |
| PoB | Peron on Board |
| PP | Process Platform |
| PPM | Parts per Million |
| PPR | Polypropylene Random Copolymer |
| PR | Purchase Requisition |
| PRD | Pressure Relief Damper |
| PRV | Pressure Reducing Valve |
| PSI | Pound per Square Inch |
| PSV | Pressure Safety Valve |
| PTM | Project Technical Manager |
| PU | Package Unit |
| PUF | Polyurethane Foam |
| PUF | Power Utilization Factor |
| PV | Plug Valve |
| PVC | Poly Vinyl Chloride |
| Q | |
| QA | Quality Assurance |
| QC | Quality Control |
| QMS | Quality Management System |
| QP | Quality Procedure |
| QTY | Quantity |
| R | |
| RA | Return Air |
| RAD | Return Air Duct |
| RAD | Return Air Diffuser |
| RAG | Return Air Grille |
| RAM | Reliability, Availability, Maintainability |
| RAM | Random Access Memory |
| RC | Room Criteria |
| RC | Reinforced Concrete |
| RCP | Reflected Ceiling Plan |
| RD | Roof Drain |
| RFQ | Request for Quote |
| RH | Relative Humidity |
| RLA | Rated Load Amperage |
| r.m.s. | Root Mean Square |
| RP | Riser Platform |
| r.p.m. | Revolutions per minutes |
| R/S | Run/Stopped |
| RSA | Rolled Steel Angle |
| RTU | Roof Top Unit |
| RV | Relief Valve |
| RWP | Rain Water Pipe |
| S | |
| SA | Supply Air |
| SAD | Supply Air Duct |
| SAD | Supply Air Diffuser |
| SAG | Supply Air Grille |
| SAT | Site Acceptance Test |
| SAT | Supply Air Temperature |
| SCADA | Supervisory Control and Data Acquisition |
| SCH | Schedule |
| SCT | Saturated Condensing Temperature |
| SD | Smoke Damper |
| SD | Smoke Detector |
| SDR | Supplier Document Register |
| SDR | Standard Dimension Ratio |
| SE | Smoke Exhaust (or Extract) |
| SEER | Seasonal Energy Efficiency Ratio |
| SEF | Smoke Exhaust(or Extract) Fan |
| SF | Service Factor |
| SF6 | Sulfur Hexa Fluoride (Inert gas used in GIS equipment for insulation purpose) |
| SG | Specific Gravity |
| SHC | Sensible Heat Capacity |
| SI | International System of Units |
| SIL | Safety Integrity Level |
| SMACNA | Sheet Metal & Air Conditioning Contractors’ National Association |
| SOD | Shut Off Damper |
| SOLAS | Safety of Life at Sea |
| SOS | Scope of Supply |
| SOW | Scope of Work |
| SPIR | Spare Parts and Interchangeability Record |
| SP | Static Pressure |
| SP | Soil Pipe |
| SS | Stainless Steel |
| SS | Substation |
| STA | Supplier to Advise |
| SWD | Storm Water Drain |
| SWH | Significant Wave Height |
| SWL | Safe Working Load |
| SWP | Shallow Water Platform |
| SWSI | Single Width Single Inlet |
| T | |
| TAB | Testing, Adjusting and Balancing |
| TBC | To be Confirmed |
| TBDL | To be Decided Later |
| TBE | Technical Bid Evaluation |
| TCP | Transmission Control Protocol |
| TDR | Technical Document Register |
| TEFC | Totally Enclosed Fan Cooled |
| TEG | Tri-ethylene Glycol |
| TEL | Telephone |
| TEMP | Temperature |
| TER | Telecom Equipment Room |
| TERM | Terminal |
| TEV/TXV | Thermostatic Expansion Valve |
| TOS | Top of Steel |
| TP | Test Port |
| TP | Three Phase |
| TPA | Third Party Agency |
| TPN | Tripole & Neutral (Also Three Phase & Neutral) |
| TQ | Technical Query |
| TR | Ton of Refrigeration |
| TR | Temporary Refuge |
| TR | Transformer |
| TS | Technical Specification |
| TSP | Total Static Pressure |
| TT | Temperature Transmitter |
| TV | Television |
| TYP | Typical |
| U | |
| UCP | Unit Control Panel |
| UFD | Utility Flow Diagram |
| UG | Under Ground |
| UL | Underwriters’ Laboratories |
| ULPA | Ultra-Low Particulate Air |
| UOM | Unit of Measurement |
| uPVC | Unplasticized Polyvinyl Chloride |
| UPS | Uninterrupted Power Supply |
| UV | Ultra Violet |
| V | |
| VAV | Variable Air Volume |
| VCD | Volume Control Damper |
| VDT | Video (or Visual) Display Terminal |
| VFC | Voltage Free Contact |
| VFD | Variable Frequency Drive |
| VP | Vent Pipe |
| VRF | Variable Refrigerant Flow |
| VRV | Variable Refrigerant Volume |
| VSD | Variable Speed Drive |
| VTA | Vendor to Advice |
| W | |
| WB | Wash Basin |
| WBT | Wet Bulb Temperature |
| WC | Water Column |
| WC | Water Closet |
| WCR | Weight Control Report |
| WG | Water Gauge |
| WHA | Water Hammer Arrester |
| WHP | Well Head Platform |
| WP | Waste Pipe |
| WP | Weather Proof |
| WPO | Wind Park Owner |
| WPQR | Welding Procedure Qualification Record |
| X | |
| XLPE | Cross-linked Polyethylene |
| Z | |
| ZCV | Zone Control Valve |