Autodesk introduced Revit for all three disciplines of Architecture, Structure and MEP for the AEC industry, and it has gained immense popularity since then. It has empowered organizations to reduce on-site concerns and rework, ultimately reducing overall project costs. Revit MEP Drawings take care of all the main services including ductwork modelling and ductwork fabrication, which precisely is the reason for jotting down this article. We would like to draw attention towards how Revit is used for modelling and how it is used for fabrication?
If we consider ductwork as a discipline, it is a core feature of MEP design projects as it facilitates heating, ventilation and air conditioning, fondly known as HVAC, for regulating the air flow and to maintain acceptable indoor air quality and the thermal comfort as well.
Revit MEP 2D drafting showcases circular, elliptical and rectangular, the three types of shapes, ductwork essentially comes in. They are designed to be fitter at varied elevation levels. Revit MEP Modeling, since inception, has been delivering an array of options to design ductwork models, however; there are several challenges that sheet metal fabricators face when modelling ductwork in Revit. Ductwork, unique in design for each of the structures and elements expose several challenges while designing.
BIM service providers or 3D BIM modelers are required to create ductwork models, through CAD drafting or 3D CAD modeling, to accommodate customized frames, windows, fittings and complex routings. They also need to design specific outlets for ductwork to fit in the outlets, while leaving adequate space for electrical and plumbing requirements.
Ductwork has to be modeled in various shapes and sizes that suit the design requirements along with factors including flow of air and mode of discharge or exhaust. Oversized ducts may pose design challenges in form of failing to accommodate the electrical and plumbing requirements, whereas undersized duct may end up as a serious design flaw that is unable to hold the desired amount of air flow. Ductwork modelers usually model to a high level of detail – LOD, at LOD 300 and increasing to LOD 350.
Though it is a component of MEP, designing a ductwork model does require expert inputs and precise layout plans to create a clash free duct network for building and engineering projects. The model should be equipped to seamlessly accommodate plumbing and electrical lines without causing costly design changes at on-site construction level.
Prior to the usage of Autodesk Revit, the AEC industry and specifically the MEP discipline relied on AutoCAD MEP – the 3D tool, and several other specialist tools and add-ons including CAD duct to create ductwork models. Revit was full of shortfalls and incomplete areas for mechanical services and ductwork, at the time of inception.
However; Autodesk was prompt enough to fix nearly all of them in later versions, elevating the tool to a stage where it can be undoubtedly used for detailed design to address the challenges and requirements. Revit now equipped to address requirements interfacing fabrication level details, as discussed further in the article.
Along with modeling capabilities, Revit also provides several other advantages including:
- Provide quantity take-offs at an early stage to help you avoid costly design changes in the later part of the design process.
- Provide accurate quantities for ductwork, insulation and other materials.
So now it was a phase that seamless ductwork models were prepared conveniently using Revit. However; the functionality of the design files on various other platforms remained one of the challenges. Example: Ductwork files designed in Revit, if were to be used for fabrication purpose on related software, due to the incompatibility on other software, the duct layouts had to be re-modeled leading to delayed time lines and more expenses incurred in the fabrication process. This also at times resulted in fabrication errors which gave negative implications while assembling the ductwork.
In order to overcome these fabrication limitations, Autodesk updated Revit features for ductwork modeling in Revit 2017 version. It is not well equipped with tools to design duct fabrication which is already a part of the package. This empowers designers and modelers to create the ductwork models, layouts and designs across the project lifecycle, which includes the fabrication teams as well.
Now the Revit files with wider compatibility for fabrication tools such as FABMEP, are like a savior for designers and modelers to design ductwork seamlessly across platforms and save the project on a single/common file without affecting the actual design. This was the first time it happened, or else this level of interoperability was never experienced from design, detailing, fabrication and futuristic facility management peripheries.
Revit MEP by Autodesk is an established tool for ductwork modeling that addresses the core elements of a ductwork system, allowing a reasonably sound set of design drawings to be issued. Challenges for fabrication from Revit was a big area of concern, till the time Autodesk started addressing them; and now we see successful fabrication interoperability.
Apart from all these, Revit is working more closely with fabrication tools which it seems has compelled the fabrication industry to adopt Revit models, which was not the case few years back.
End results, what everyone expects and will get, will certainly be accurate designs that are delivered faster and efficiently. Ultimately all this will reduce the costs and improve timescales in the engineering and building industry.