The Lowdown on LOD: A brief guide

September 26, 2017

Cranes on a building site

What is LOD? In the world of Building Information Modelling (BIM), LOD stands for Levels of Definition and is a term used to describe the precision of a model. However, with other terms like Level of Information (LOI) and Level of Detail (also LOD) floating around, it can be difficult to work out how these terms all fit together. Let’s find out more:
 
The Jargon: Getting back to basics

Before going any further it’s important to fully understand the key phrases involved:

  • BIM Model: a virtual model of the project, based on data that evolves and grows throughout the planning process, acquiring more data from each contractor or contributor as they become involved.  
  • Common Data Environment (CDE): This is the one-stop location for all the shared data relating to a project, usually stored on an online cloud-based site. All project stakeholders can access this data to facilitate collaboration, but individual intellectual property rights are still maintained.
  • Levels of Definition: The different amounts of data in the model, including Level of Information (LOI) and Level of Detail (LOD) - see below.  This data can be graphical or non-graphical and must always be clearly organised.
  • Level of Information: The amount of non-graphical data in the model.  This can include……
  • Level of Detail: The amount of graphical data in the model.  This can include…..
  • PAS 1192-2:2015: The current guidance for Levels of Definition in the UK.  Published by the BSI, a full copy is available here: https://shop.bsigroup.com/forms/PASs/PAS-1192-2
  • COBie (Construction Operations Building information exchange): The COBie is a spreadsheet containing non-graphic information from the building information model, of which it is considered a subset. This could be described as asset data not relating to the physical dimensions of the project. This spreadsheet can be collectively accessed and added to over the course of the project’s lifecycle.

But before we dive into the specifics, let’s first take a look at how the Levels of Definition (LOD) emerged.

 

Data, data, everywhere: the push for BIM Level 2

Looking back, the development of Levels of Definition (LOD) stems from the Government’s push for BIM Level 2.  Since April 2016 it’s been a mandatory requirement on all publically tendered projects in the UK to be at BIM Level 2.

 

BIM Maturity Levels

Source: PAS 1192-2:2013 Specification for information management for the capital/delivery phase of construction projects using building information modelling
https://shop.bsigroup.com/forms/PASs/PAS-1192-2/
© The British Standards Institution 2013. Published by BSI Standards Limited 2013.


 
Focusing on effective collaboration between stakeholders, with accurate information, BIM Level 2 requires a sharing process such as a Common Data Environment (CDE).  PAS 1192-2:2013 specification was introduced to specify the amount of type of data that would be required at certain stages of the construction and operation of the building.
 
Seven key stages in a project were identified, when key information should be available.  They include Brief, Concept, Definition, Design, Build & Commission, Handover & Closeout, and Operation.  Further details of these stages are detailed in the PAS1192-2:2013 diagram below:

 

PAS 1192-2:2013 Specification for information management for the capital/delivery phase of construction projects using building information modelling
Source: PAS 1192-2:2013 Specification for information management for the capital/delivery

phase of construction projects using building information modelling
https://shop.bsigroup.com/forms/PASs/PAS-1192-2/
© The British Standards Institution 2013. Published by BSI Standards Limited 2013.

 

It should be further noted that although these key stages are detailed in terms of data requirements, the exact timings of these are not advised and must be specified by the employer, usually to coincide with key decision points within the project.
 
AOK on the LOD?

That’s the gist of LOD. It helps ensure the level of data and the reliability of Building Information Models throughout different key phases in the construction project. 
 
Want to learn more on BIM?Take a look at our new knowledge centre contructible.trimble.co.uk.

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