BIM, MEP and structural glossary
Plain-English definitions of the terms that come up on engineering design and BIM projects, with links to where we explain them in more depth.
A
- As-built drawings
Drawings or a model updated at the end of construction to show what was actually installed, including site changes. Building owners use them for maintenance and future alterations.
B
- BEP (BIM Execution Plan)
The document that sets out how BIM will be used on a project: who models what, to which level of detail, in which software and file formats, with what naming conventions and exchange dates.
- BIM (Building Information Modelling)
Designing a building as a coordinated 3D model that carries information (sizes, materials, systems, quantities) rather than as separate 2D drawings. Drawings, schedules and quantities are taken from the model.
- BOQ (Bill of Quantities)
A list of the materials and work items in a design with their quantities, used by contractors to price the job and by clients to compare tenders.
- Builder's work drawings (BWD)
Drawings that show the openings, sleeves, plinths and supports the civil contractor must leave for services, so ducts and pipes don't need holes cut on site later.
C
- CAD to BIM
Converting existing 2D CAD or PDF drawings into an intelligent Revit model, usually to coordinate services or create a record of an existing building.
- CDE (Common Data Environment)
The shared online space where a project team stores, reviews and issues models and drawings, for example Autodesk Construction Cloud, SharePoint or a structured shared drive.
- Clash detection
Running software checks on the combined models of all disciplines to find where elements occupy the same space (hard clashes) or break clearance rules (soft clashes), so they are fixed before construction.
- COBie
A spreadsheet-based format for handing over building asset information (equipment, spaces, warranties) from the design and construction team to the owner's facility management system.
- CSD (Combined Services Drawing)
A drawing that shows all building services (ducts, pipes, cable trays, sprinklers) together in one ceiling void or shaft, with levels and clearances, after coordination.
D
- Design basis report
A short report agreed at the start of design that fixes the codes, design conditions, loads and systems to be used, so everyone designs to the same assumptions.
E
- ETABS
Structural analysis and design software widely used for buildings. It models the frame and calculates the effects of gravity, wind and earthquake loads.
F
- Federated model
A model that links together the separate architectural, structural and MEP models so they can be viewed and clash-checked as one, while each discipline keeps ownership of its own file.
- Fire NOC
In India, the No Objection Certificate from the fire department confirming that a building's fire safety design meets the code. It is needed for many building types before occupation.
G
- GFC (Good for Construction) drawings
The final, coordinated drawing set issued for the contractor to build from, after approvals and design reviews.
H
- Heat load calculation
Working out how much heat a space gains from sun, people, lights and equipment, which decides the size of the air conditioning system room by room.
- HVAC
Heating, ventilation and air conditioning: the systems that control temperature, humidity and fresh air in a building.
- Hydrant system
A fire fighting system of pumps, pipes and valves that supplies water to hose connections around and inside a building for the fire brigade and trained occupants.
I
- IFC (Industry Foundation Classes)
An open file format for BIM models that lets different software exchange model data, for example a Revit model shared with a team using another BIM tool.
- ISO 19650
The international series of standards for managing information over the life of a building using BIM, covering roles, naming, information requirements and the common data environment.
L
- LOD (Level of Development)
How far a model element has been developed, from LOD 100 (a symbol or mass) to LOD 500 (verified as built). It is set per element in the BIM scope.
- LOI (Level of Information)
How much non-graphical data an element carries, such as manufacturer, model number, performance and maintenance details, separate from its geometric detail.
M
- MEP / MEPF
Mechanical, electrical and plumbing (and fire protection): the building services that make a building comfortable, powered, supplied with water and safe.
N
- NBC 2016
The National Building Code of India 2016, the reference code for building design in India, including Part 4 on fire and life safety and Part 9 on plumbing.
P
- PEB (Pre-engineered building)
A steel building whose frames, purlins and cladding are designed as a system and fabricated in a factory, then bolted together on site. Common for warehouses and factories.
- Point cloud / Scan to BIM
A laser scan of an existing building produces a point cloud of millions of measured points; scan to BIM is modelling the building in Revit from that scan.
- Purlin
A horizontal steel member that spans between the main frames of a steel building and supports the roof sheeting.
R
- Revit
Autodesk's BIM software for architectural, structural and MEP modelling, with drawings and schedules generated from the model.
- Revit family
A reusable Revit component, such as a pump, light fitting or door, with its geometry and parameters. Good families keep models accurate and light.
- RFI (Request for Information)
A formal question from a contractor or consultant asking the design team to clarify missing or conflicting information.
- Riser diagram
A vertical schematic showing how a service (water, drainage, fire, electrical) runs up through the floors of a building.
S
- Shop drawings
Detailed drawings prepared for fabrication or installation, such as steel assembly drawings or duct fabrication drawings, based on the design drawings.
- Single-line diagram (SLD)
A simplified electrical diagram showing how power flows from the supply through panels and distribution boards to the loads, with breaker and cable sizes.
- Sleeve
A pipe or opening cast into a wall, slab or beam to let a service pass through later. Planning sleeves early avoids cutting structure on site.
- Sprinkler system
An automatic fire protection system of pipes and heads that discharge water over a fire when the heat breaks a glass bulb or fusible link in the nearest head.
T
- Tekla Structures
Steel and concrete detailing software used to produce fabrication-ready models, shop drawings and material lists.
V
- VRF (Variable Refrigerant Flow)
An air conditioning system where one outdoor unit serves many indoor units, each controlled separately, by varying the refrigerant flow to each.
W
- Wet riser
A vertical fire main kept permanently full of water, with landing valves on each floor for fire fighting in taller buildings.
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