This paper describes research on a computer model for building energy simulation. The main goal of this effort has been to provide building designers a better design tool for energy optimization in their building design processes. With the rapid development in computing technology, today's expectation for computer-aided building design (CABD) systems have matured to an advanced level—to the point where designers are open to the idea of computers helping them in the thought process and not just being used to manipulate and represent geometric shapes [ J. Pohl et al., 1992. A Computer-Based Design Environment—Implemented and Planned Extensions of the ICADS Model. Design Institute Research Report, CADRU-06-92, California Polytechnic State University, San Luis Obispo, CA.]; [ J.A. Clarke, A.D. Irving, 1988. Building Energy Simulation: An Introduction, Energy and Buildings, 10 (1988), Elsevier, pp. 157–159.]. By its very nature, design is a multidisciplinary and creative activity which encompasses all the relevant areas to be considered during the design process. Thus, the CABD system of today is expected to be a general purpose integrated system, rather than a domain-dependent isolated graphics system [ J. Pohl, L. Myers, A. Chapman, J. Cotton, 1989. ICADS: Working Model Version 1, Design Institute Research Report, CADRU-03-89, California Polytechnic State University, San Luis Obispo, CA.]. This research effort embodies a prototype interface system for a building energy simulation model (ENERife). This interface system is not a simple layer between user and simulation model, but rather, a general interface strategy to control simulation models and relevant databases to be integrated into CABD. The system includes a user interface module, system interface module, general database handling module, automated input processor, building matrix system, and a result analysis and recovery system.