Interoperable software makes it possible to seamlessly exchange data among different compliant applications. Among other benefits, this offers opportunities to increase the quality of building energy simulation through simultaneous interaction of multiple design and simulation tools, possible because of direct data exchange among them.This paper discusses the new IFC HVAC extension schemata that are included in the latest release of the IFC data model (IFC2x2) and the new functionalities and industry processes it now supports. It describes an example of interoperable software environment, possible gains from interoperable simulation, and discusses current issues in data exchange for such simulation.