IfcOpenShell is an open source (LGPL) software library that helps users and software developers to work with the IFC file format. The IFC file format can be used to describe building and construction data. The format is commonly used for Building Information Modelling. IfcOpenShell uses Open CASCADE (the Open CASCADE Community Edition) internally to convert the implicit geometry in IFC files into explicit geometry that any software CAD or modelling package can understand.
A python wrapper on top of IfcOpenShell can be used with pythonocc to provide additionnal feature. Check blog post at http://blog.ifcopenshell.org/2014/12/combining-ifcopenshell-and-pythonocc.html
IfcOpenshell home page: http://ifcopenshell.org/