As the design process grows in complexity and technological integration, BIM/CAD software has become a fundamental tool for designers in a range of fields. But choosing which to use can be a challenge. How can you tell whether CAD or BIM modeling is right for certain project types? What about understanding the difference between BIM and CAD on a practical level? In this guide, we compare the strengths of these tools and assess ultimately why BIM is better than CAD for complex and collaborative projects.
The acronym “CAD” stands for Computer-Aided Design. CAD softwares are used as drafting tools to lay out project designs. They allow for drawings and blueprints to be created digitally and saved as revisable files. It is possible to create both 2D and 3D design representations in CAD. However, among the AEC community, “CAD” is commonly used to describe 2D modeling.
The acronym “BIM” stands for Building Information Modeling. BIM softwares contain information about all the different components represented in a design model, such as materials and equipment. For example, clicking on a window in BIM would display all of the information about that window’s brand, material, dimensions, efficiency rating, glass options, finish options, life cycle, and even price.
Such complexity can lead to the question: what is a BIM file? BIM files hold all of the project data about each individual BIM object (i.e. elements representing windows, materials, and other components) used in the model. These file types tend to be proprietary, featuring file extensions unique to the program they were created in.
For example, BIM files produced in Revit will have a “.RVT” extension. However, Industry Foundation Classes (“.IFC”) file types are commonly used as well. IFC files are non-proprietary, open data file formats. Revit and Archicad are examples of popular programs for BIM project creation.
BIM and CAD can both play powerful roles in construction projects. Their applications can overlap, but they also diverge quite a bit.
CAD is more of a multi-discipline design tool, usable for everything from building designs to machinery and furnishing. So while CAD software can be used to design toys and equipment, it can also be used to draw up the floor plans and models of an architectural project.
BIM, on the other hand, is focused specifically on the design and documentation of buildings. A building modelled in BIM will be augmented with data that can be used to analyze how that design will manifest and perform in the real world. This data makes it easier to manage BIM projects, since lists of products and materials are all stored right within the BIM file, and various project contributors can more effectively see how their work interacts with the rest of the model.
BIM for landscape designers is also emerging as the best way to develop intelligent, well-managed terrains. Whereas traditional architectural models for landscape features (i.e. drainage, piping, topography) were only visual tools, BIM models are now being used to tally project costs, assess energy impacts of plantings and irrigation systems, and even predict growth patterns and maintenance needs.
CAD to BIM conversions are possible. But it’s important to note that not all CAD software is designed for BIM compatibility.
In fact, some of the more advanced CAD files that do contain richer data sets for design elements can lose all of this information when they are converted over to BIM format. For cases in which the programs used do not facilitate smooth conversion of CAD to BIM, there exist conversion services.
Compatibility is most easily found using programs that come from the same developer. For example, CAD files created in Autodesk’s AutoCAD program can be readily transferred to Autodesk BIM 360.
As BIM becomes more widespread in the architectural environment, there is a bit of controversy surrounding using BIM vs CAD workflows. Many firms and professionals are reluctant to adopt BIM because they have already been using CAD for many years. Their operations and processes are built around CAD software, and making the switch to BIM can require a significant investment of resources.
But transitioning to BIM enables designers to harness all the benefits of greater efficiency, collaboration, and documentation. Designers and project stakeholders are better able to forecast the costs, maintenance, and performance of their buildings and properties. In an industry where budgets are often strained, risk minimization is key, and projects are required to meet increasingly ambitious energy and sustainability goals, BIM is becoming an essential tool for precise, successful management of intricate projects that entail multi-disciplinary teamwork.
Experts predict that CAD will continue to advance to better work alongside BIM. Some think it is likely that the BIM format will evolve enough to take over completely, eliminating the need for manual drafting altogether. Anticipating that the AEC industry will soon be powered by BIM, firms large and small would do well to transition now and gain a leading edge.
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