BIM for the Confused: Part 1 – What is BIM?
In its most basic form BIM (or Building Information Modelling) is a way of managing all the information required in a building project.
It is an expanding, and increasingly important topic which depends upon a large amount of technical information and building data. In this series of blog posts, over the next few weeks, we hope to provide an introduction to BIM for people who may not have come across this before, or who have seen some information but found it slightly confusing. We will be looking at what BIM is, the different formats used and how it has developed as well as discussing some of the advantages of using modelling as part of a construction project.
BIM involves modelling all the components that make up the building through the documentation of non-graphical and graphical information that will define the delivered project. This is done through the Project Information Model (PIM). Upon completion of the build, the Asset Information Model (AIM) comes into being which can be considered a knowledge resource and continually maintained information model about the building throughout its usable lifecycle (operation) to demolition.
The building can be modelled not just in the 3 physical dimensions of height, width and depth but also by time and costs, giving an accurate representation of the building’s development in a virtual form and data about the building’s performance throughout its lifecycle. The level of information available in particular aspects of the model can vary depending on the level of maturity of the data provided by the manufacturer of the product, or by the designer, so some parts of the model may be more detailed than others.
The data about each product that makes up the building project: such as windows, heating systems and insulation, is made available by the manufacturer. The data is the main component of the product ‘Object’, for example Kingspan Insulation Limited has ‘Objects’ for standard products such as Kooltherm K8 Cavity Board. This is a 3D model of the product, containing within it important and relevant data to be used in the building model. For example we have geometric data such as standard board size and thickness, technical data such as thermal resistivity and water vapour transmission, and other chosen data such as GWP and Green Guide Rating.
This data can then be used in 3D CAD modelling packages (such as Revit, ArchiCAD, Vectorworks and Bentley) to create designs for building projects, performance analysis for the proposed design, and information for regulatory approval and construction. The end result would be a model which shows the project from the initial concept through the design stage to construction and end use. The model will directly reflect what has been built and can be used by anyone involved in the project. It will form the basis for other documents which are required when the building is occupied, such as health and safety information and provide data for ongoing maintenance.
One key consideration is the format of the data so that it is accessible to as many organisations and software packages as possible and this is a topic which we will be exploring in a later blog post.
The Government is supporting the BIM model and, following on from their ‘Construction Industry Strategy 2011’ has mandated that all public procured construction projects from 2016 onwards should use BIM.
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