What is BIM? A brief introduction to Building Information Modelling and its use in building services
From the Autodesk website:
“Building Information Modelling (BIM) is the holistic process of creating and managing information for a built asset. Based on an intelligent model and enabled by a cloud platform, BIM integrates structured, multi-disciplinary data to produce a digital representation of an asset across its lifecycle, from planning and design to construction and operations.”
In simpler terms, from our discipline of Building Services, BIM allows us to design and fully coordinate in 3D all the Mechanical, Electrical & Public Health services within a building and factor in information into the equipment in the model.
The development of Building Services design drawings over the last 30 years has been huge. From the 1980s onwards the drawing board was gradually replaced by the computer. Computer Aided Design (CAD) programs, specifically AutoCAD, enabled the process of producing & especially amending drawings to become much quicker & easier, and storage could also be reduced as the documents would be kept on drives and printed out on demand for transmittal.
Building Services CAD drawings are usually produced in 2D, and these were usually individually hermetic, meaning coordination exercises and drawings were needed to be produced separately to demand. Issues would generally arise when buildings have a large number of services routing to risers on one floor for example, large items such as ventilation and containment crossing where the building space is minimal. To coordinate these, individual sections would be drawn to suit, but these would be solely produced for the worst-case areas, so how can we check that the services through the whole building work?
Coordinated 2D Section Through Corridor in AutoCAD
The answer is BIM, and specifically in our case, Autodesk’s Revit program. This allows us to work intelligently and cooperatively with #Architects, #Structural engineers and the wider design teams 3D models to produce a coordinated, unified model. We can then produce working drawings and sections from the model.
Coordinated Services Running at High Level in Revit Model (2D)
Coordinated Services Running at High Level in Revit Model (3D)
BIM is still just a tool though, and it needs strong communication within the team environment to work properly. For the team to get the best out of the program this needs to be a collaborative process where the engineer works closely with the BIM technician to ensure the services work physically within the space and head off any clashes with the building structure in a way that would not be feasible in 2D AutoCAD.
BIM also allows for manufacturers equipment models (known as families) to be inputted directly so that size and specification information are available within the model, this can be used to automatically create schedules. A more in depth method of data input ‘COBie’ can be used to
“electronically capture and record important project data at the point of origin, including equipment lists, product data sheets, warranties, spare parts lists, and preventive maintenance schedules. This information is essential to support operations, maintenance and asset management once the built asset is in service”
BIM is not the perfect solution as it can be a slower and therefore more expensive process than 2D AutoCAD and is not always suitable for many projects where services coordination isn’t a major issue. Also, many sub-contractors will install from the 2D drawings only, with no reference to the 3D model.
But for buildings with large scale services where space may be at a premium it can be an extremely useful tool for the modern building services engineer.