I’d like to present Blender, the heavyweight 3D CG suite, to be used as a free and open-source BIM authoring tool to add to suite of tools out there. It is part of IfcOpenShell and developed here:

GitHub IfcOpenShell/IfcOpenShell Open source IFC library and geometry engine. Contribute to IfcOpenShell/IfcOpenShell development by creating an account on GitHub.

It is relatively brand new in its ability to write IFC files, but Blender has been able to read IFC files for a while now, also part of IfcOpenShell. It is still under heavy development, so it is not expected for use by end-users yet, but for those who are willing to give it a shot, it already has many interesting features, such as:

Supports writing IFC4 files first and foremost.

Lots of clever reuse of representations to create efficient and small IFC files and you have full control over exactly how you optimise the IFC file, including generating products from parametric arrays and object group instances

Supports the spatial tree including multiple buildings, multiple sites, and so on

Create product compositions including extremely granular breakdowns

Create project libraries, not just projects

Quantity take-off calculations

Property sets

Modeling abilities are completely separate from BIM data. In contrast to other tools where the type of object governs how you can model it, in Blender it is totally separate and you can instantly convert an object from one type to another, change its aggregation, change its spatial location such as changing floors, etc without any fear or breaking your model

Export with/without quantities, or with/without representations (hint: an export without geometry retains all of the useful BIM data but is extremely fast to export, and creates a tiny IFC filesize!)

Blender’s native Python API allows you to script it heavily doing bulk IFC data management very easily

Obviously you get immediate access to all of Blender’s amazing features like modeling in real-time rendered view like a game engine. Beautiful visuals. Animation. File linking. Proxy objects. Virtual reality. Light simulation, CFD analysis, energy modeling. Huge ecosystem of addons. The list just goes on and on.

You can see the created model here in IfcOpenShell’s cross-platform IFC viewer:

If any early adopters are willing to start battle testing it, let’s go!