This paper details a development of a real-time Hardware-in-the-loop (HIL) testbed for analysis of advanced and intelligent building control strategies using a real-time emulator. Models running on this real-time emulator are created using a non-proprietary, object-oriented, equation based language, namely, Modelica. A case study of single maximum control logic for a variable air volume (VAV) box in a single thermal zone is presented to illustrate the whole procedure.