Digital and BIM
BIM modelling at every level of detail
MEP models produced at the level of information need the stage requires, from LOD 100 massing to LOD 500 as-installed record.
- Discipline
- Digital and BIM
- Typical timescale
- Modelling runs with the design; the level is agreed at Stage 1 or 2
WHAT IT IS
Level of detail — or, in the language BS EN ISO 19650 actually uses, level of information need — is the answer to how much a model is supposed to contain at any given point. It is the difference between a duct drawn as an indicative route reserving space and a duct carrying its size, material, insulation thickness, pressure class and manufacturer reference.
SDE models at whatever level the stage and the appointment require, from indicative space reservation through fully specified technical design to a record model updated with as-installed information.
The levels commonly named on UK appointments run roughly as follows. LOD 100 is conceptual: systems shown as symbols or massing, enough to prove space exists. LOD 200 is generic: elements with approximate size, shape and location, suitable for spatial coordination. LOD 300 is specific: accurate size, shape, location and orientation, which is the level most technical design work is delivered at. LOD 400 adds fabrication and installation detail and is normally the contractor's responsibility rather than the designer's. LOD 500 is the verified record of what was actually installed.
WHEN YOU NEED IT
Whenever the appointment states a BIM deliverable, and — more usefully — whenever the modelling effort has to be agreed before it is spent. Modelling to LOD 400 what the brief only needed at LOD 200 is expensive and slow; modelling to LOD 200 what the contractor was promised at LOD 300 causes an argument at tender.
The level is set in the BIM Execution Plan and confirmed against the exchange information requirements, so it is a Stage 1 or 2 conversation rather than a Stage 4 discovery.
OUR PROCESS
The required level is agreed per element and per stage rather than declared once for the whole model. A plant item and a small power circuit rarely need the same treatment at the same time.
Models are checked against the agreed level before each information exchange, so a delivery either meets what was asked for or the shortfall is stated. Clash detection is run continuously through the design stages, not compiled into a report at the end when nothing can be moved.
DELIVERABLES
What you receive
- MEP model at the agreed level of information need
- Level of information need schedule by element and stage
- Clash detection reports and resolution tracking
- Federated model coordination
- Model audit against the exchange information requirements
STANDARDS
Standards applied
The editions in force at the time of design. Where a standard is amended mid-project we confirm which edition the appointment is based on.
- BS EN ISO 19650-1:2018Concepts and principles, including level of information needBSI
- BS EN ISO 19650-2:2018Delivery phase of the assetsBSI
- BS EN 17412-1:2020Building information modelling — level of information need — concepts and principlesBSI
- BS 8541Library objects for architecture, engineering and constructionBSI
- BSRIA BG 6Design Framework for Building ServicesBSRIA
QUESTIONS
Common questions
What do the LOD levels mean?
LOD 100 is conceptual massing, LOD 200 is generic elements with approximate size and location, LOD 300 is specific elements with accurate size, shape, location and orientation, LOD 400 adds fabrication and installation detail, and LOD 500 is the verified as-installed record. Most consultant design is delivered at LOD 300, with LOD 400 normally sitting with the installing contractor.
What is the difference between LOD and level of information need?
LOD is an informal industry shorthand for geometric detail. Level of information need is the term used by BS EN ISO 19650 and defined by BS EN 17412-1, and it covers geometrical information, alphanumerical information and documentation together. A model can be geometrically detailed and still fail the information requirement if the data attached to it is missing.
What level of detail should be specified in an appointment?
The level that the next user of the information actually needs, stated per element and per stage rather than as a single number for the project. Specifying a uniformly high level across a whole model is the most common way of paying for modelling nobody uses.