Specifying the level of detail and the timing of information delivery required in BIM models, there are pre-defined stages within BIM execution plans to guide the process from conceptual approximation to detailed implementation. Howthe Level of Development (LOD) is employed throughout various project phases is set up by these stages. Comprehending the LOD framework and ensuring its standardized application is imperative for optimizing the project lifecycle in the AEC industry.
In this context, a Level of Development unity is required for better workflow integration that prioritizes performative and economic evaluations.
Though often used interchangeably in Building Information Modeling (BIM), the terms Level of Detail (LOD), Level of Development (LOD), and Level of Definition (LOD) stand for distinct aspects of model accuracy and purpose. As each term addresses varying graphical representations and informational content within the model, precise differentiation is critical for effective BIM execution.
© Understanding BIM: The Past, Present and Future
The ‘Level of Development’ of a model is distinguished by the quantity and quality of information it incorporates, whereas the term ‘Level of Detail’ particularly corresponds to the geometric representation of the model. As per the definition given in the BIM Teaching and Learning Handbook: Implementation for Students and Educators, ‘Level of Description’ encompasses Level of Detail (LOD) and Level as it implies interdisciplinary communication, a more comprehensive concept of Information (LOI). On the other hand, the level of information (LOI) focuses on alphanumeric or non-graphical qualities.
Initially, the American Institute of Architects (AIA) introduced five levels of Level of Development (LOD) that define the scope of development of a BIM model. Subsequently, a collaboration with the American BIM Forum resulted in the proposition of an expanded number of LOD levels. It follows that INNOvance introduced eight levels of development. These levels are designated as LOD000, LOD200, LOD300, LOD350, LOD400, LOD500, and LOD550. Requiring well-structured coordination among all professionals and stakeholders collaborating on the project, these levels indicate the roles and responsibilities for the progression of elements and the degree of detail in the BIM model.
According to the ensuing levels of development (LOD) and their associated information, the American Institute of Architects (AIA, 2013), the Construction Industry Council (CIC, 2013), and the BIM Forum (2013) propose a structured framework that explains the progressive proliferation in accuracy and detail of model elements throughout the multifarious stages of the project lifecycle.
The BIM Forum’s reference document covers the varying development levels for BIM models throughout the design and construction phases. Allowing users to apprehend a framework and standardize their models according to shared parameters and information is considered a compelling communication tool.
The Fundamental Definitions of Levels of Development (LOD)
Outlined by the BIM Forum can be sequentially listed as follows:
LOD 100
“The Model Element may be graphically represented in the Model with a symbol or other generic representation but does not satisfy the requirements for LOD 200. Information related to the Model Element (i.e., cost per square foot, tonnage of HVAC, etc.) can be derived from other Model Elements.”
Phase: Conceptual Detail
LOD 200
“The Model Element is graphically represented within the Model as a generic system, object, or assembly with approximate quantities, size, shape, location, and orientation. Non-graphic information may also be attached to the Model Element.
Phase: Schematic Design
LOD 300
“The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of quantity, size, shape, location, and orientation. Non-graphic information may also be attached to the Model Element.”
Phase: Construction Detail
LOD 350
“The Model Element is graphically represented within the Model as a specific system, object, or assembly in terms of quantity, size, shape, orientation, and interfaces with other building systems. Non-graphic information may also be attached to the Model Element.”
Phase: Construction
LOD 400
“The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of size, shape, location, quantity, and orientation with detailing, fabrication, assembly, and installation information. Non-graphic information may also be attached to the Model Element.”
Phase: Shop Floor
LOD 500
“The Model Element is a field verified representation in terms of size, shape, location, quantity, and orientation. Non-graphic information may also be attached to the Model Elements.”
Phase: As-Built
Wellington Place © Tekla
Classifying Levels of Definition
In a complementary yet different way, the classification of Level of Definition proceeding in an order can be taken as a more holistic ground for apprehending what the necessary information required at each stage through the project lifecycle. The following list presents the Classification of Levels of Definition in a systematic mode, as recapitulated in the BIM Management Handbook.
Brief: Establishes the fundamental model and includes crucial project details such as site limitations, standards, and performance requirements. It also determines the baseline for subsequent design and execution objectives.
Concept: Reveals an early model that reflects the original aesthetic direction, purpose of design, and execution objectives. Essential design development, analysis, and coordination are provided. The model is still flexible and can be used for cost estimation, coordination, and scheduling.
Developed: A coordinated, dimensionally accurate model that reflects the solution to the design requirement and the intent for aesthetics, along with certain performance information that can potentially be utilized for analysis, design development, and early contractor involvement. The model can be used to agree on a first-stage target price and for coordination, sequencing, and estimation reasons.
Production: The model satisfies planning and regulatory requirements since it is dimensionally accurate and coordinated effectively. It sets the base for integrated design models created by qualified contractors. Coordination, sequencing, and expense estimation, including establishing an objective pricing or Guaranteed Maximum Price (GMP), can also be accomplished with the model.
Installation: By considering the design contributions of specialized subcontractors and the qualities that go alongside, a precise model of the asset is created for use before and during construction. The orchestration of fabrication procedures, installation sequencing, and the documentation of as-built conditions for future use are all essential aspects of this model of operation.
As: A precise document that details the asset’s construction at transition, encompassing all information requisite to its operation and sustained maintenance.
In Use: An up-to-date report of the asset at a particular moment in time, incorporating any significant alterations while containing all the necessary information for operation and maintenance, as well as performance and condition data over time.
In conclusion, there is an important software tool that is effective for the development and management of a BIM Execution Plan (BEP) called LOD Planner. It enables users to specify the required level of detail for the BIM model throughout the design and construction phases while it also clarifies the team’s responsibilities.
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