BIM, in plain language
Standards, terms and workflows explained simply, with pointers to the documents to read next.
134 entries
Start here: the essentials
- StandardsISO 19650 overviewThe international series of standards for managing information over the life of a built asset using BIM — what each part covers and the ideas they share.
- WorkflowsBEP (BIM execution plan)The delivery team’s plan for how it will produce, check and deliver information to meet the client’s requirements.
- WorkflowsCDE (common data environment)The agreed source of project information, with a workflow that moves containers through work in progress, shared, published and archived.
- StandardsLOD vs LOINHow the Level of Development scale differs from ISO’s level of information need, and why ISO 19650 projects describe geometry, data and documents separately.
- SoftwareIFC (Industry Foundation Classes)The open, vendor-neutral data format and schema for exchanging building and infrastructure models between software.
- StandardsIDS (Information Delivery Specification)A buildingSMART standard for writing information requirements as machine-readable rules, so IFC models can be checked automatically.
- SoftwareBCF (BIM Collaboration Format)An open format from buildingSMART for exchanging model-based issues — with viewpoints, comments and element references — between BIM tools.
- WorkflowsClash detection types (hard, clearance, duplicate)The three kinds of clash test — physical overlap, insufficient clearance and duplicated elements — and what each is good for.
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- 4D and 5D BIM (time and cost)Linking model elements to the construction programme (4D) and to quantities and cost (5D), and what each is useful for.
- 4D planning (linking the programme to the model)Connecting each activity in the construction programme to the model elements it builds, so the sequence can be watched, checked and explained before it happens on site.
A
- AI in construction and BIM (what works today)A practical map of where AI helps across design, construction and operations today, where it is still a demo, and the questions to ask before using it on a project.
- APIs for BIM softwareHow programs talk to BIM software and platforms, desktop APIs, cloud APIs and file-based access, and what each lets you automate.
- Appointed partyA party appointed by a lead appointed party to provide information, such as a consultant or specialist subcontractor.
- Appointing partyThe ISO 19650 term for the client: the organisation that receives information about the works from those it appoints.
- As-built verification and record modelsChecking that what was built matches the model (or updating the model so it does) before it becomes the record that operations rely on for decades.
- Asset information requirements (AIR) in practiceThe client's statement of which assets it needs information about, which properties for each, in what format and when, written so a delivery team can actually provide it.
- Asset registerA list of the assets an organisation maintains, with their identity, location, type and key data.
- Asset tagging and identificationGiving every maintainable asset a unique, readable identifier that appears on the asset, in the model, on drawings and in the maintenance system, so all four point to the same thing.
- Autodesk Platform Services (APS)Autodesk's cloud APIs (formerly Forge) for reading, viewing, converting and automating models and project data in Autodesk's cloud, including Autodesk Construction Cloud.
- Automated code checkingChecking a building model against building regulations by software: rules written in a form a computer can test, run against model data, with a report a reviewer still reads.
B
- BCF (BIM Collaboration Format)An open format from buildingSMART for exchanging model-based issues — with viewpoints, comments and element references — between BIM tools.
- BEP (BIM execution plan)The delivery team’s plan for how it will produce, check and deliver information to meet the client’s requirements.
- BIM authoring softwareThe main families of software used to create models — architecture, structure, services, civils and fabrication — and what to agree when teams use different ones.
- BIM coordinatorThe role that brings models together, checks them and manages coordination issues between disciplines.
- BIM dimensions (3D, 4D, 5D, 6D, 7D)A popular way of naming what a model is used for: 3D geometry, 4D time, 5D cost, and 6D and 7D, whose meanings vary between sources and are defined by no standard.
- BIM objectA reusable model component, such as a manufacturer’s product or a generic element, with geometry and information.
- BIM usesThe specific purposes a model serves on a project — such as coordination, quantity take-off or handover — and why every requirement should name one.
- bSDD (buildingSMART Data Dictionary)An online service from buildingSMART that publishes classifications, properties and their definitions, so requirements and models can refer to shared, unambiguous terms.
- Building data, BMS and IoT sensorsThe live data buildings produce (from building management systems, meters and IoT sensors) and how it connects to the asset and space data from BIM.
C
- CAFM and CMMS systemsThe software that facilities and maintenance teams run buildings with, what data it needs from BIM, and why handover data so often fails to load into it.
- Case study: Camino Medical Group, Mountain View, BIM with leanA medical office building for Sutter Health's Camino Medical Group, where trades modelled and coordinated their systems early, combined with lean methods, to shorten the time to build.
- Case study: Crossrail (Elizabeth line), information managementLondon's east–west railway set up a common data environment and asset information system for a programme of many contractors, aiming to hand the operator one trusted source of information.
- Case study: Heathrow Terminal 5, the T5 Agreement and the single model environmentBAA kept the project's risk itself under a partnering agreement and asked its suppliers to work in one shared model environment, an early forerunner of today's common data environment.
- Case study: HMYOI Cookham Wood, the first UK government BIM Level 2 trialAn extension to a young offender institution in Kent, the first of the Ministry of Justice's BIM Level 2 early adopter projects, combining BIM with collaborative procurement.
- Case study: Singapore CORENET, BIM submissions and automated checkingSingapore's government built an online system for building submissions, and over two decades moved it from drawings to models, with automated checks of selected rules.
- Case study: Sydney Opera House, BIM for facility managementAn early, well-documented attempt to use building models to run a famous building that was designed long before BIM: what the research project tried, and what it shows about information for operations.
- CDE (common data environment)The agreed source of project information, with a workflow that moves containers through work in progress, shared, published and archived.
- CDE platformsThe software used to run a common data environment — document management, model hosting, workflows and approvals — and what to check when choosing or setting one up.
- Clash detection types (hard, clearance, duplicate)The three kinds of clash test — physical overlap, insufficient clearance and duplicated elements — and what each is good for.
- Clash groupA set of related clash results treated as one coordination problem, such as one duct run crossing several beams.
- CM at risk (construction manager at risk)A delivery method in which a construction manager joins during design as an adviser, then takes on the risk of building the project for a guaranteed maximum price.
- COBieConstruction Operations Building Information Exchange — a spreadsheet-shaped format for handing over asset information to the people who run a building.
- Combined scale factorThe factor that converts distances between a map grid and the ground: grid scale factor times elevation factor. Small per metre, large over a long corridor.
- Constructability reviewChecking, with the people who will build it, that a design can be built safely, in a sensible order and at a sensible cost, before it reaches site.
- Coordinate reference systems and EPSG codesHow positions on Earth are described — datums, projections and grids — and why every project should name its system with an EPSG code.
- Coordination and model checking softwareThe tools used to federate models, run clash and rule checks, and manage issues — what they do and how they fit into the coordination cycle.
- Coordination issueA recorded problem between models or disciplines, with an owner, status and due date, tracked until it is resolved.
D
- Data dropAn older UK term for a planned delivery of information at a project stage, now called an information exchange at a milestone.
- Delivery teamA lead appointed party together with all the appointed parties and task teams under it.
- Design risk registerThe designers' record of significant health and safety risks in a design: how each was eliminated or reduced, and what remains for others to manage.
- Digital twinA digital representation of a physical asset that is kept in step with it through live or regular data, used to monitor, predict and decide.
- Drawing revisionsHow changes to a drawing are recorded: revision codes, revision tables, clouds and triangles, and the transmittals that prove who received which revision.
- Drawing symbols and legendsThe conventions that make a drawing readable: line types, symbols, hatches and abbreviations, defined for each set in its legend.
E
- EIR (exchange information requirements)What the client needs from an appointment — which information, in what form, at which milestones — written so the delivery team can plan and price it.
- EPSG codeA number that identifies one coordinate reference system or transformation exactly, from the EPSG registry.
F
- Fabrication models and DfMAModels detailed enough to make parts from, and design for manufacture and assembly (DfMA), where buildings are designed as kits of parts made off site.
- Field BIM (models on site)Getting the model and its data to the people building on site, on tablets and in site offices, so they install from current information and report back what they find.
G
- Generative and computational designDefining a design problem as goals, rules and variables so software can generate and compare many options, and what it needs from BIM data to be useful.
- GeoreferencingPlacing a model in its true position on Earth — linking the model’s local coordinates to a real coordinate reference system with an origin, an angle and a scale.
- GIS and survey file formatsThe common open formats for geographic, survey and infrastructure data, and how each one relates to IFC and BIM workflows.
- GUID (IFC GlobalId)The unique identifier that every IFC object carries, which should stay the same each time a model is exported.
H
I
- IDM (Information Delivery Manual)A buildingSMART method, published as ISO 29481, for describing who exchanges which information with whom, when and why, before anyone decides how it is encoded.
- IDS (Information Delivery Specification)A buildingSMART standard for writing information requirements as machine-readable rules, so IFC models can be checked automatically.
- IFC (Industry Foundation Classes)The open, vendor-neutral data format and schema for exchanging building and infrastructure models between software.
- IFC entity (class)A type of object defined in the IFC schema, such as IfcWall, IfcDoor or IfcSpace, which tells software what an element is.
- IFC versions and MVDs (IFC 2x3, IFC 4, IFC 4.3)Which IFC versions exist, what changed between them, and how model view definitions limit what an export contains.
- IfcAlignmentThe IFC 4.3 entity that describes a road, rail or other alignment with its horizontal, vertical and cant parts, so elements can be placed along it.
- IfcBuildingElementProxyThe generic IFC class used when an element has no better classification — usually a sign of a missing export mapping.
- Information containerAny named, persistent set of information in the CDE — a model file, drawing, document, schedule or data set.
- Information container namingThe field-based naming convention for files and other containers — project, originator, volume, level, type, role and number — and why each field exists.
- Information delivery milestoneA point in the project when information is due to be exchanged, checked and accepted.
- Information managerThe role responsible for information management: requirements, the CDE, the BEP, plans and checks, rather than modelling itself.
- Information modelAll the structured and unstructured information about a project or asset — not just the 3D model.
- Information protocolThe project-specific terms for information — rights, duties, liabilities and use — incorporated into each appointment.
- Information requirements (OIR, AIR, PIR, EIR)The four kinds of information requirement in ISO 19650 — organisational, asset, project and exchange — and how each one feeds the next.
- IPD (Integrated Project Delivery)A delivery model in which the owner, designers and builder sign one multi-party agreement and share risk and reward, usually with a shared office (the big room) and a shared model.
- ISO 19650 overviewThe international series of standards for managing information over the life of a built asset using BIM — what each part covers and the ideas they share.
- ISO 19650-3: the operational phaseThe part of ISO 19650 for information management while assets are in use, how the asset information model (AIM) is set up, kept current and fed by projects and events.
- ISO 55000 (asset management)The international standards for managing physical assets over their whole life, and why they matter to BIM: they explain why owners ask for asset information in the first place.
L
- Last Planner SystemA lean planning method in which the people who do the work plan it together, week by week, and measure the share of promises kept (percent plan complete).
- Lead appointed partyThe party appointed directly by the client that coordinates information from a whole delivery team, for example the lead designer or main contractor.
- Level of accuracy (LOA)How closely surveyed or modelled positions match reality — the USIBD scale from LOA10 to LOA50 — and how it differs from level of development.
- Level of information need (LOIN)The ISO way of saying how much information each deliverable needs: geometry, data and documents described separately, for a purpose and a milestone.
- Location breakdownHow a project is divided into buildings, levels and zones, used consistently by models, programmes and cost plans.
- LOD levels (100–500) explainedThe Level of Development scale used to say how far a model element has been developed and how much it can be relied on, from conceptual 100 to field-verified 500.
- LOD vs LOINHow the Level of Development scale differs from ISO’s level of information need, and why ISO 19650 projects describe geometry, data and documents separately.
M
- MCP (Model Context Protocol) for BIM toolsThe open protocol that lets AI assistants use tools and data, and what MCP servers for Revit, Autodesk's cloud, IFC and other BIM software make possible, and risky.
- Measurement and cost classification standards (NRM, ICMS, UniFormat, MasterFormat)The rules that say how construction work is grouped and measured for cost, and why a model that ignores them gives quantities an estimator can't use.
- MetadataInformation about an information container, such as its status, revision, classification and author, stored alongside it in the CDE.
- MIDP and TIDPThe delivery plans in ISO 19650 — each task team’s list of information containers (TIDP) and the lead appointed party’s combined master plan (MIDP).
- Model checkingChecking a model against rules before it is shared or accepted — information, naming, geometry, structure and coordination — and recording the result.
- Model data and dashboardsTurning model and project data into dashboards that answer real questions (progress, quality, quantities, issues) and the data pipeline behind them.
- Model elementAn object in a model that represents a physical or functional part of the asset, such as a wall, beam, pipe or space.
- Model federationCombining separate discipline models into one coordinated view without merging them, so each team keeps ownership of its own model.
- Model health checksRoutine checks of an authoring model’s condition — warnings, file size, links, unused content, worksets and set-up — that keep it fast, stable and fit to share.
- Model-based estimating (5D)Using quantities from the model, mapped to a cost structure and priced with rates, to produce and update estimates, and knowing which parts of the estimate the model can't provide.
- MVD (Model View Definition)A defined subset of the IFC schema for one purpose, such as coordination or reference viewing, that software exports and imports so both sides agree what the file holds.
O
- O&M informationOperation and maintenance information handed over with a building: manuals, warranties, certificates and maintenance instructions.
- OmniClassThe North American classification system for the built environment — 15 linked tables covering facilities, spaces, elements, products, work results, roles and more.
- openBIMAn approach to BIM based on open, vendor-neutral standards such as IFC, BCF, IDS and bSDD.
- OpenCDE and model serversbuildingSMART's open APIs for connecting common data environments and tools (BCF API, Documents API, Foundation API), and the model servers that store models as queryable data rather than files.
- Order of precedenceThe contract clause that says which document wins when drawings, specifications, schedules or models disagree.
P
- Parameter (property)A named value attached to an element or type in an authoring tool, such as height, fire rating or manufacturer.
- PAS 1192 and BS 1192 (the UK predecessors)The UK documents that ISO 19650 grew from — what each covered, which parts of ISO 19650 replaced them, and why you still meet their terms.
- PIM and AIM (project and asset information models)The two information models in ISO 19650 — the project information model built up during delivery, and the asset information model used to run the asset.
- Planned maintenance and maintenance standards (SFG20)How maintenance regimes are defined, how standards like SFG20 describe tasks and frequencies, and how BIM data links each asset to its regime.
- Point clouds and scan-to-BIMMillions of measured 3D points captured by laser scanners or photogrammetry, and how they are turned into models of existing buildings and sites.
- Professional seal (engineer's stamp)The seal or stamp a licensed engineer or architect places on drawings and documents to take legal responsibility for the design shown.
- Progress tracking with models and reality captureMeasuring what has actually been built, against the model and the programme, from site updates, scans, photos or drones, so delays show up in weeks rather than months.
- Project base pointThe point in an authoring model that serves as its local origin for design coordinates.
- Project information standardThe project’s rules for producing information: naming, codes, classification, units, coordinates and formats.
- Property sets (Psets) and quantity setsHow IFC groups element information into named sets of properties and quantities, the standard Pset_ and Qto_ sets, and custom sets.
R
- Reading IFC with code (IfcOpenShell, web-ifc)Opening IFC files with open-source libraries to count, check, extract and report, without any authoring software, and what a first script looks like.
- Record model (as-built)A model updated to show what was actually built, used as the basis for handover information.
- Responsibility matrixThe table that assigns who produces, checks and approves each piece of information and each information management task, at high and detailed levels.
S
- SchemaThe formal definition of a data structure: which objects, attributes and relationships a format may contain.
- Security-minded approachManaging information about sensitive assets so that it cannot be used to cause harm, as described in ISO 19650-5.
- Shared coordinatesAn agreed coordinate system used by every model on a project, so they line up when federated.
- Shared parameterA project-defined parameter with a fixed identity that can be used across many families, models and schedules.
- Site logistics modelsModelling the temporary site, from cranes, hoists and scaffold to deliveries, storage and welfare, and how it changes over time, so the site works as well as the building.
- Soft landings (BS 8536)Involving the people who will operate a building throughout design and construction, and supporting them after handover, so the building works as intended, now set out in BS 8536:2022.
- Space data and space managementRooms and areas as data (names, numbers, areas, uses, occupants) and how a well-structured model gives operations the space data they plan, clean, charge and report with.
- SpecificationsThe written part of the design: what materials must be, how work is carried out and checked, and how it is measured and paid.
- Stationing and chainageHow positions are given along a linear project: the distance along a named alignment (chainage or stationing) and the offset from it.
- Suitability and revision codes (S1, P01, C01…)The metadata codes that say what a container may be used for (status) and which version it is (revision), as defined in the UK National Annex to ISO 19650.
- Survey pointA point in a model that corresponds to a known point in the real-world coordinate system, linking the model to the survey grid.
T
- Task teamA group of people performing one specific task within a delivery team, such as the structural design team or a cladding subcontractor’s modellers.
- Title blockThe fixed panel on every drawing sheet that identifies the sheet, the project and the people responsible, with its scale, revision and status.
- Tolerance (clash)The distance below which a clash test ignores an overlap, so tiny modelling overlaps are not reported.
- Track geometryThe shape of a railway track in plan and profile, plus the cant between the rails, within tight tolerances: what designers set and maintainers keep.
- True north, grid north and project northThe three norths on a project: towards the geographic pole, along the map grid, and the drawing’s convenient up direction.
- Type and instanceThe two levels at which elements carry information: the shared definition (type) and the individual placed element (instance or occurrence).
U
- UniclassThe UK’s unified classification system for the built environment — tables for complexes, entities, spaces, elements, systems, products and more, with codes like Ss_25_10_30.
- Utility network recordsThe owner's records of its pipes, cables and fittings, usually in GIS: features with attributes and connectivity, used to operate, maintain and isolate the network.
- Utility quality levelsThe grading of existing utility information by how it was obtained, from records only (D) to exposed and measured (A), used by PAS 128 in the UK and ASCE 38 in the US.
V
- ViewpointA saved view of a model — camera position, visible and selected elements, sections — used to show exactly where an issue is.
- Visual programming and scripting (Dynamo, Grasshopper, pyRevit)The tools BIM people use to automate their own work, from drag-and-connect graphs to Python scripts, and how to choose between them.