BIM software works by building a digital model of a project out of intelligent 3D objects - walls, doors, beams, ducts - each carrying data about what it is, what it's made of and how it performs. Drawings, schedules, quantities and analyses all come from that one model, so a change made once shows up everywhere. There are four types of BIM software: planning, authoring, analysis and use.
Building information modeling, or BIM, software tools help designers and builders create and manage building projects. But how does BIM software work, and what do you actually get from using these BIM tools?
My blog post takes an in-depth look at how BIM software helps professionals design and build, the four types of BIM software, and how designers and contractors each use them. If you want a list of products to compare, Jennee has that covered in the 10 best BIM software programs. This post is about what's going on underneath.
1. What Is BIM Software?
Building Information Modeling (BIM) is a process that uses 3D BIM modeling technology to create a digital representation of a construction project before it is built. BIM software is the set of tools that makes that process possible.
With the aid of BIM software, architects, engineers and construction professionals can collaborate on a building's design and structure in three dimensions, with a large amount of data attached to each 3D object.
The software gives users a place to input data, such as measurements and material specifications, and to generate outputs like drawings and construction schedules. That data builds a virtual model of the building that can be explored and interrogated from every angle.
The big difference from CAD is that CAD draws lines that only mean something to the person reading them, while BIM software models objects that know what they are: a door knows it's a door, how wide it is and which wall it sits in. That's why BIM drawings stay in step with each other.
BIM software helps construction professionals avoid errors and oversights, saving time and money. Ultimately, BIM helps to create better buildings that are safer, more efficient and more sustainable.
2. How Does BIM Software Work?
BIM software works by creating three-dimensional (3D) objects that come together as a building model you can view from multiple angles and perspectives.
In practice, it works in five steps:
- You model with objects, not lines. Walls, slabs, doors, windows, pipes and beams come from libraries of parametric objects, so you can resize and change them without redrawing anything.
- Each object carries data. As well as its geometry, every object holds properties: its type, material, fire rating, manufacturer, cost or anything else the project asks for. How much detail is needed at each stage is the project's level of information need.
- Every drawing is a view of the model. Plans, sections, elevations, 3D views and schedules are generated from the model, so when you move a wall, every drawing and schedule that shows it updates too.
- Models are shared and combined. Each discipline usually authors its own model. The models are shared through a common data environment (CDE), often exchanged in the open IFC format, and combined into one federated model to look for clashes.
- The model is checked and used. The information in each model is checked against what the project asked for, then used for quantities, 4D sequencing, energy analysis and, after handover, running the building.
The model is populated with data that describes the geometry, materials, systems and components of the building, and that data can generate 2D drawings, energy analysis reports, construction schedules and other documents.
BIM software applies rules and analysis to the physical side of a building: its geometry, spatial relationships, location and component properties. Architects and engineers can use the results early in the design process to avoid problems and optimise the building's performance.
3. The Benefits of Using BIM Tools
Some of the key advantages of using BIM software include:
- Improved communication: a virtual model of the building gives every stakeholder the same clear picture of the project requirements, which helps avoid misunderstandings and delays during construction.
- Increased efficiency: plans, sections and elevations come straight from the 3D model, so designers spend less time preparing and updating drawings.
- Better quality control: engineers can compare work in place with the 3D model to find where construction differs from the design, and catch defects before they're built in.
- Reduced costs: teams can see the impact of a design decision early and change it before the project begins, which avoids costly blunders and delays during construction.
- Faster project delivery: the construction process can be planned and managed more accurately, which helps avoid delays and disruption on site.
- Improved sustainability: BIM tools can assess a building's energy performance and help optimise the design to reduce its carbon footprint.
Good read: What is building information modeling technology? My thoughts along with 3 bonus resources
4. The Four Different Types of BIM Software
There are four main types of BIM software, and they all work together in a complete BIM process:
| Type | What it does | Examples |
|---|---|---|
| 1. Planning | Sets out what information is needed, from whom and by when, and checks what's delivered | Plannerly |
| 2. Authoring | Builds the 3D models and produces the drawings | Revit, Archicad, Tekla Structures |
| 3. Analysis | Combines, coordinates and tests the models: clashes, rules, structure, energy | Solibri, Revizto, Navisworks, STAAD.Pro |
| 4. Use | Puts the model to work after handover: operations, maintenance, digital twins | Unity and digital twin platforms |
First, BIM planning tools coordinate the different stages of a building project and set your BIM project off on the right track. They let you write the BIM Execution Plans (BEPs) and information requirements (like the Exchange Information Requirements, EIR, and Asset Information Requirements, AIR), plan who delivers which model and document by when, and automatically check the model deliverables. This is where Plannerly sits - yes, it's ours, and yes, I use it every day. The free lesson on creating project documents like the EIR, PIR and BEP shows how planning works in practice, and you can start from the free BEP template with the guide to writing a BEP your teams actually use.
Second, BIM authoring tools are used to create the actual 3D models of buildings and their components. Each discipline on a building project usually has its own authoring tool. Some of the most popular today are Autodesk Revit, ArchiCAD and Tekla Structures.
Third, there are BIM analysis tools, which simulate how a building will perform and test the authored models to find problems before anything is built. They check that the different elements of the building (walls, floors, ceilings, doors, windows and so on) are properly coordinated and fit together, and that the design meets the rules it has to - which can save time, money and embarrassment in the long run. Popular BIM analysis tools include Solibri, Revizto, Autodesk Navisworks and Bentley Systems' STAAD.Pro. Checking the information in each model - does every element carry the data the project asked for? - is a related job, and it's what Plannerly's Verify module does.
Finally, BIM use tools help professionals manage and maintain a building after it has been built. These tools can track maintenance schedules, monitor energy use and more. The term Digital Twin is now often used to describe how BIM data can track and manage a building through its whole life cycle. One example is Unity, popular in gaming as well as architecture, which uses virtual models of buildings to help facility managers optimise operations and build digital twins.
How the four types work together
On a real project, the four types hand over to each other: the planning tool says what's needed, the authoring tools produce it, the analysis tools test it, and the use tools run the building with it. Most of the time lost on BIM projects is lost in those handovers - a requirement nobody modelled, a model saved in the wrong place, a check run against last month's version.
Open standards keep the handovers clean: IFC for models, BCF for issues and buildingSMART's IDS for requirements a machine can read (here's IDS explained). The free lesson on openBIM principles and tools covers all three, and connecting to Autodesk Construction Cloud (ACC) and other CDEs shows how Plannerly picks up models from where your team already shares them. Jennee's list sorts the same tools into finer groups: authoring, coordination, model checking, CDE and BIM management.
Want the whole process on one page? Download the free ISO 19650 workflow diagram (PDF) (opens in a new tab).
5. How Does BIM Software Work for Designers
One of the most fundamental steps in using BIM tools is the creation of the model by the designers, with the authoring tools.
The software for designers and engineers usually includes a library of building components, so designers can quickly insert chairs, doors, windows and other elements into their designs.
These components are usually parametric, which means they can be quickly resized and customised to meet the specific requirements of a project.
Designers can also use BIM software to create realistic renderings of their designs, which help when marketing or presenting to clients. Renderings help sell a design concept and give clients a better idea of how the finished building will look.
The same tools then generate construction documents, such as plans, sections and elevations, exported to PDF or DWG and sent to the construction team.
6. How Does BIM Software Work for Contractors?
Contractors use BIM to help them plan, construct and commission buildings. As well as using the architect's model, some contractors build their own models for specific uses, such as 4D sequencing, which links the model to the construction programme to show how the job will be built, week by week:
Or a detailed virtual mock-up of a tricky detail before it's built for real, or a model better suited to accurate quantity take-off and cost estimating.
These models are also used to run more detailed 3D clash detection.
Clash detection is a process where the trade contractors' models are merged into a single model, so the whole project team can find and resolve the issues before construction begins.
Clash detection checks geometry. Checking information is a separate job: does each model carry the data the contract asked for, at the right milestone? That's model checking, and the free model checking intro lesson shows how it works.
Good reads: My top 10 uses for BIM in construction management, Construction management software: my 10 best tips to streamline your process and 9 benefits I see using virtual design and construction (VDC).
7. The Future of BIM Technology
The ultimate goal of BIM is to create a single source of truth for all information about a building project - from the layout to data on the construction materials, MEP systems and even the occupants!
BIM software keeps evolving and new features arrive all the time. I believe that by using BIM technology and processes, we can transform how buildings are designed and built. Three changes I'm watching:
- Requirements machines can read. With IDS, the information a project asks for becomes a file that software checks automatically, instead of a PDF the modellers skim once.
- AI for the routine work. Drafting documents and filling the obvious gaps, while people stay in charge of the decisions.
- Models that outlive the project. Handover data that feeds facility management and digital twins, rather than a box of files nobody opens.
BIM will matter even more as we move towards more sustainable construction. It reduces our reliance on paper drawings and physical models, and gives us virtual models that are more accurate and easier to update and manage - which helps cut waste at every stage of a building's life cycle.
Conclusion
So how does BIM work?
Well, design and construction projects need an immense amount of coordination between many different trades and professions, and new ways of working make that especially hard to get right.
BIM software helps, but the best outcomes only happen if you have a solid plan: what the project needs, who delivers it, and how you'll check it. Start with 10 example BIM goals and my guidelines for successful BIM projects.
If you're looking to simplify your BIM management process, I highly recommend using Plannerly. It keeps track of your project from the BIM execution plan to the last model check, and you can start free.
I also suggest you check out Jennee's top 10 BIM software list too!
I blog for the Five BIM Bloggers series, where every week we share different perspectives on important BIM topics. To hear our views first, join Plannerly free or browse the Plannerly BIM blog.
