by Paul Swaddle
This is part of a series of articles looking at The Digital Plan of Work
Project information evolves over time to reflect how designs change through various work stages. At its simplest, this information management takes place in two arenas. NBS platforms focus on the development of non-graphical, text data such as specification outputs and product content from manufacturers, conveying performance characteristics, client requirements or testing. In parallel, graphical work (typically in 3D model environments) evolves with design decisions. Typically, design often focuses on an asset developing in this way, from early massing and master planning to sketch design, technical coordination and the drawing outputs from model environments like plans, elevations, sections and details. Clients procure the building asset, and a wealth of digital information for future stages and long-term use.
To ensure delivery of the required data but reduce wasted effort and rework, it is essential that the amount of detail to be provided at each stage of design development is clearly understood and agreed by all parties, considering risk, responsibility, delegation and collaboration.
Level of detail
There are several industry guides that break the project timeline into work stages. One common example of this is the RIBA Plan of Work, overhauled in 2013, and updated to its current form in 2020 to describe an industry-wide approach to design development. The framework breaks down projects into eight stages, such as ‘Concept Design’, ‘Spatial Coordination’ or ‘Technical Design’.
But how much information is required from a design team, contractor or manufacturer at each of these stages? Along with defining design responsibility, the management of the outputs required in the process can be simplified into two basic questions:
- How much graphical data is required at this stage, and who is producing it?
- How much non-graphical, specification and text-based data is required at this stage, and who is producing it?
Defining these project deliverables in accurate terms is essential, but a decade ago, UK organizations wanting to describe and agree the amount of data expected by the end of a work stage in contracts used a range of methods. Design responsibility matrices were sometimes explained using standards and specifications developed in the US, like the AIA E202 BIM Protocol or US BIMForum Level of Development bands, which didn’t reflect typical UK projects or procurement. In addition, it was felt that it would be useful to divide the single LOD definitions into two separate bandings – one for geometric detail and one for related information.
The result of an Innovate UK-funded project, NBS worked with industry to fill this gap with the BIM Toolkit. It is a collaborative platform allowing users to record the current work stage of the project and to indicate the amount of information required for each building system, with a clear structure for the data to be documented and shared with other project stakeholders. Along with capturing requirements at each stage and allowing users to record that those outputs had been delivered before proceeding, the platform also let the client and project team designate who was responsible for the information.
The Toolkit content followed the PAS 1192-2 approach of differentiating between graphical and non-graphical information, and used indicative ‘bandings’ to suggest how much data was required at each stage with the terms:
- LOD = ‘level of detail’ (graphical); and
- LOI = ‘level of information’ (non-graphical).
Whilst these terms are now superseded by BS EN ISO 19650, BS EN 17412-1 and the ‘Level of Information Need’ approach, it is a useful shorthand to think about these two aspects of data development happening in tandem – particularly to focus on the idea that the model environment doesn’t contain all the data, and that many aspects of non-graphical information are in the specification, preliminaries or product test reports.
Design development across the project stages
If level of detail is how much graphical data is required at each stage, how do the bandings help project teams to reach agreement?
Design work, from early sketches to final details, develops in response to changing requirements, the latest information and client preferences. The outputs from the 3D model environment – plans, sections, elevations, images and details – tend to become more visually complex as the project evolves. Numerous dimensions, object locations, complicated geometry, and detailed schedules and quantities, will be captured in the model for construction, and to assist with accurate pricing and cost information.
The expectation is to provide the correct amount of detail at the correct stage of the project, which reflects what is required and the allocated responsibilities. Sometimes, too much geometric detail (for example, a fabrication-quality model object provided by manufacturers or project teams at the wrong stage) can waste time, team effort or computing resources. Just as you wouldn’t expect a fully detailed specification at an early stage if only a description of performance was needed for a contractor-designed part of the job, each part of the model should provide a level of detail appropriate to the stage of the project and its interaction with other systems.
The Toolkit provided over 400 sets of LOD illustrations: indicative examples of how much data might be typical for, e.g. a boiler system at spatial coordination stages, or a doorset system at technical design detailing. These were created with the support of BDP and Mott MacDonald, with the aim of encouraging agreement between clients and project teams about what each party needed to know at a given project stage – and the limits of this information, with expectations being set early to avoid problems further down the line.
The NBS BIM Toolkit LOD bandings
For easy communication, the Toolkit bandings were given single-digit numbers from 2–5, as reflected in the BIM Protocol and PAS 1192 suite of documents. These provide a straightforward way of describing the amount of data expected from the responsible team or organization at each work stage. This allows future use of the information for the next project stage (e.g. coordination, tendering or environmental analysis).
The online versions of these definitions were retired in June 2022, but a generic description of the bandings is provided below.
How does this align with LOIN (Level of Information Need)?
Since the introduction of the BIM Toolkit in 2015, information management and digital construction processes in the UK and worldwide have matured significantly, which means that the tools and guidance authored then may be less relevant to industry professionals working today. NBS is updating its guidance to reflect new workflows and international development of standards, but wants to ensure that Toolkit users have access to existing information and LOD bandings.
Most UK practitioners followed the approach to split development bandings between graphical detail and non-graphical information. Around the time of the launch, there were more than twenty-five international variants of BIM documentation containing some version of levels of detail or graphical development.* The release of ISO 19650 aimed to standardize a fully international approach to many aspects of information management processes. Now, redefining the original deliverables in UK PAS 1192 documentation – and refining ISO 19650 and its UK National Annex, BS EN 17412-1 and UK BIM Framework-associated guidance – breaks down level of information need and early consideration of the purpose of information for particular users across an asset’s life cycle.
Rather than just a progressive evolution of geometrical complexity, the requirement is to consider what the model information will be used for (e.g. spatial coordination, clash detection or rendering purposes) and provide relevant outputs at the appropriate level of, e.g. visual complexity, dimensional accuracy, geolocation, or consistent naming and classification. The need will be different for each system or deliverable, so the amount and type of information required and produced at each stage will vary accordingly. Perhaps the division of geometric ‘model detail’ properties and non-visual ‘information’ levels may have been based in traditional ideas of distinct delivery teams producing these types of data on a typical project. However, level of information need should encourage project teams to collaboratively consider all the potential aspects of an item’s graphical data developing across the project timeline for agreed purposes, in parallel with evolving non-graphical information, including robust specifications and updated product information. *https://www.bimthinkspace.com/2016/07/the-many-faces-of-lod.html (last accessed June 2022)
NBS LOD GuidesAs part of the 2014/15 Innovate UK funded BIM Toolkit project, NBS worked with BDP and Mott MacDonald to produce a set of ‘LOD guides’.
The guides may be downloaded by completing the form below.