After a brief review of the underlying technology for the implementation of the inference engine, the paper demonstrates an actual design session using a bi-directional thermal simulation tool. Specifically, a use-scenario is described in which the designer explores the tradeoffs between various design variables (glazing area, glazing type, and floor mass) in view of the resulting energy performance of a typical residential building. The paper concludes with a discussion of the potential and limitations of the bi-directional approach toward active convergence support for performance-oriented design development.