BIM: model behaviour

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Published: 08 August 2018


Building Information Modelling (BIM) promises to revolutionise the way buildings are designed and operated. But what exactly is it? Darren McMullan at Brymec offers a definition of BIM and explains how it works.

The take-up of Building Information Modelling (BIM) has been relatively sluggish since it was first brought to the wider attention of the construction sector in the UK government’s Construction Strategy published in 2011. However, though it is starting to gain momentum as awareness of its business benefits grows, there remains considerable confusion over what BIM actually is and how it operates.
BIM is a way of working rather than a tangible object. It is essentially the process of delivering and operating built assets (which include buildings, bridges and roads) using structured digital information to which all members of the project team have access. It does this by generating and managing digital representations of physical and functional characteristics of places.

BIM requires the project team to contribute information about a proposed building in a shared digital space called a ‘common data environment’. This is where digital information comes together and allows everybody who needs to see it to do so. 

Information contained in the common data environment can include specifications, schedules, performance requirements, cost plans, and so on. It also includes three-dimensional (3D) drawings created on a computer by members of the project team. These are then consolidated into a single 3D model to ensure that they co-ordinate before being shared with the wider project team. 

Non-graphical information is linked to the graphical 3D model. So, for example, when you click on different parts of the graphic, you can access information about it. Clicking on an air handling unit, for instance, might give you information about the manufacturer, lead time, cost and performance levels. The combined grouping is called a ‘dataset’ or ‘information model’.

BIM comes in various levels
  • BIM Level 0 signifies a lack of Building Information Modelling with unmanaged computer-aided design (CAD) and no collaboration between those collating information about a built asset.
  • BIM Level 1 indicates that the data has assumed a structure. The CAD is 3D or 2D with some commonality in the data environment. A measure of collaboration is in place but full collaboration between different parties has not been reached.
  • BIM Level 2 is collaborative BIM. This has been required by the UK government for all public sector construction projects since 2016 so construction organisations must demonstrate compliance before the Treasury will release funding. At Level 2, collaboration has been introduced between teams and the process of BIM is being followed. There is still a lack of a single source of data, but crucially any data collected about a built asset is now shared. More information here.
  • BIM Level 3 is unlikely to happen in its truest sense for several more years, but when it does it will probably be an integrated solution around open standards with everyone working from a single model stored somewhere on a web service or in the cloud. It will mean there is complete collaboration in the planning, construction and operational life cycle of any built asset.

Visualisation date
At Level 2 and above, ‘BIM objects’ allow members of the project team to use manufacturer-specific building materials and components in their CAD system. Various online platforms hold an extensive collection of both generic and manufacturer BIM objects ranging from building fabric systems to mechanical and electrical objects. Visualisation data gives the object a recognizable appearance and behavioural data, such as detection zones and connection faces, enables the object to be positioned or to behave in exactly the same way as the product itself. 

Currently Brymec is working on a project to bring BIM right into the hands of the tradesman. We are linking our current suppliers BIM data to our products on our website. In addition, we are creating our own BIM objects for our ever-increasing range of directly manufactured and branded products. Brymec is also building a cloud platform where we will host our BIM objects in a central, easily manageable format. We have invested in an in-house digital design technician, to create cutting edge BIM objects for our products.

In order to function effectively, BIM employs a number of ‘tools’ – software applications that manipulate the model in order to obtain a specific outcome. Tools include software used for drawing production, rendering, visualization, specification writing, clash and error detection, energy analysis, cost estimation, scheduling and quantity take-off.
The industry leading BIM tool is Autodesk Revit which allows users to design a building and structure and its components in 3D, annotate the model with 2D drafting elements, and access building information from the building model’s database. Brymec is using Revit software, and is committed to creating the highest quality of geometric and data-rich BIM objects to assist architects, engineers and constructors in effective and accurate system design.

Benefits and drawbacks of BIM
Advantages
  • BIM increases productivity and trust among the project team, and reduces conflicts and changes during construction.
  • There is less need for rework and duplication of drawings for the different requirements of building disciplines.
  • Fewer errors are introduced into the project.
  • The increasing number of simulation tools available for use with BIM allows designers to calculate building energy performance and visualize such things as sunlight and shade on a building in different seasons. 
  • It smooths the path to greater knowledge transfer and saves valuable drafting time.
  • You can take BIM with you – you have access to the model and project details from anywhere, on any device.

Disadvantages
  • The legal implications of using BIM software have yet to be fully tested in the courts.
  • Disruption will be inevitable when introducing BIM and this must be managed carefully.
  • BIM is not universally used among construction professionals so compatibility is not guaranteed.
  • BIM involves a significant investment in both time (for training and development) and money (for software and other IT technology).
  • There is no standardised BIM platform so a construction professional could risk investing in a system that has a limited ability to interoperate with other BIM systems.