Describes the use of emulator to evaluate a building energy management system (BEMS). Major topics include setting up a BEMS and an emulator, evaluating system/command and direct digital control (DDC) software, plus methodologies for testing BEMS application algorithms. Presents considerations for evaluating the programming capabilities of a BEMS, DDC control loop performance, and rating different aspects of BEMS performance. Also includes a brief discussion of BEMS software.KEYWORDS: Building management, energy management, controls, performance, estimating.