Revit is a useful tool in the AEC industry since it was introduced. It has effectively enabled organisations to minimise the possible on-site concerns and helped to lower the overall project cost. Revit MEP covers of all of the main sets including ductwork modelling which is the subject of this particular article and specifically how it is used for modelling and how it is now being used for fabrication.
Focusing firstly on ductwork as a discipline, ductwork is a chief characterize of MEP design projects as it facilitates heating, ventilation and air conditioning (HVAC) for regulating the air flow and to continue permissible indoor air quality in addition as thermal comfort.
Duct work essentially comes in three types of shape – circular, elliptical and rectangular and they are designed to be fitted at varied elevation levels. Revit has provided an range of options in its latest update for design ductwork models, in addition there are many challenges when modelling ductwork in Revit. Ductwork is rare in design for each of the structures and all component expose different challenges while designing. BIM sets modellers must create ductwork models to adjust to customised frames, windows, fittings and complicate routings. Specific outlets are also required to be designed for ductwork to fit in the outlets in addition as to leave adequate space for electrical and plumbing requirements.
in addition as different shapes, ductwork has to modelled in different sizes in addition, to suit the design requirements along with the factors such as flow of air and mode of release or exhaust. An oversized duct may present design challenges such as failing to adjust to the electrical and plumbing requirements and under sized duct may consequence in a serious design flaw and may not be able to keep up the desired amount of air flow. Ductwork modellers typically form to a high level of detail (LOD), typically at LOD 300 and increasingly at LOD 350.
Although it is only a part of MEP design ductwork modelling does require expert inputs and precise layout plans to create a clash free duct network for building and engineering projects. This can seamlessly adjust to plumbing and electrical lines without causing costly design changes at construction level. Pre-Revit, the industry used AutoCAD MEP, a 3D tool, in addition as other specialist tools and add-ons such as CAD Duct to create ductwork models. When Revit was introduced it had a number of shortfalls and incomplete areas for mechanical sets and indeed for ductwork. However later versions have addressed earlier shortfalls and the tool is at a stage where it can be used for detailed design to address the challenges and requirements detailed above but also for interfacing with fabrication level detail, which will be discussed further below.
in addition as modelling capability, Revit also provides other advantages such as providing quantity take-offs at an early stage, which helps to avoid costly design changes in the later part of the design course of action and provides accurate quantities for ductwork, insulation and other materials. already though seamless ductwork models are prepared using Revit, the functionality of the design files across other platforms had remained limited. for example, when the ductwork form files designed in Revit had to be used for fabrication purposes on related software, due to its incompatibility on these softwares, the duct layouts had to be re-modelled leading to time delays and a more expensive fabrication course of action, resulting in fabrication errors which can have negative implications while assembling the ductwork.
To conquer the limitations for fabrication, Autodesk updated Revit features for ductwork modelling in its latest version – Revit 2017. Revit 2017 now has tools to design duct fabrication which are included within the package. This enables designers and modellers to create the ductwork models, layouts and designs for the complete project lifecycle, including fabrication teams. The files which have wider compatibility for fabrication tools such as FABMEP help designers and modellers to design ductwork seamlessly over various platforms and save the project in a single file without affecting the actual design. Historically, this level of interoperability has not been experienced from design, detailing and finally by to fabrication and in the future – facilities management.
In summary, Revit MEP is an established tool for ductwork modeling and it does address the chief elements of a ductwork system and allow a reasonably sound set of design drawings to be issued. The challenge for fabrication from Revit was always a concern and as briefly discussed, Autodesk have now started to address this and we are seeing fabrication interoperability at last. additional to this is the fact that Revit is working more closely with fabrication tools independent and consequently the fabrication (manufacturing) industry is now starting adoption of Revit models in a way that has not before been experienced. The end game will surely average accurate designs, delivered faster and consequently more efficiently – helping to reduce costs and enhance timescales in the engineering and building industry.