© 2007 ASHRAE. ABSTRACT When used early in the design process, simulation can help designers reduce a building’s energy demand. Early-stage simu- lation must allow the user to explore many options quickly. Most building simulation programs have been structured for modeling finalized building designs very accurately. Intricate detail, often including CAD models, must be entered before such simulations can take place. This can take hours or days to prepare, which is not useful for early-stage design iteration. Further, most simulation tools require a technical background and substantial user training before they may be used effectively. By simplifying the modeling process, and specifically the user-interface, it is possible to make simulation tools accessible to a wider audience. The MIT Design Advisor is presented as means for non-technical specialists to rapidly simulate and compare energy consumption of early-stage building designs. An overview of the simplified interface and the rapid energy model are given, and sample validation cases are explored. The MIT Design Advisor is available at http://designadvisor.mit.edu. INTRODUCTION In this paper a case is made for a new category of simu- lation tools that are appropriate for nontechnical building designers. One such tool, developed by the authors, is then presented. A description is given of the simplified user inter- face, which has been condensed to a single page of basic build- ing parameters. Next, an overview is presented of the energy- load simulation procedure. Finally, validation cases are made for key components of the model, showing agreement with accepted tools. A NEW CATEGORY OF DESIGN TOOLS The art of building simulation is well established and experienced professionals can compute building loads with practical confidence. Building simulation packages are in no short supply. The motivation for creating yet another class of simulation tools is to combat the excessive complexity that makes many tools inaccessible to building designers, archi- tects, and engineers for early stage design comparisons. Build- ing simulation is typically deferred to post-design analysis. Consequently the simple, inexpensive opportunities for reduc- ing energy consumption in buildings are often overlooked. Simplified approaches in both interface design and modeling technique can help empower the non-technical designer to make better design choices. Building Simulation Engines Because of their extensive feature-set, building simula- tion engines such as Energy Plus and DOE-II lend great modeling flexibility to the experienced technical user. In this class of software usability is typically compromised in favor of increased ability to model complex building scenarios. Many underlying assumptions are made without being explicitly evident to the casual user. Users must have a detailed under- standing of the simulation process to make useful design comparisons. To compound the issue, most of these engines lack a pre- packaged simplified user interface. Inputs must be prepared as large text files fraught with technical jargon, physical proper- ties, and programming constructs. Preparing input files can be A Simplified Rapid Energy Model and Interface for Nontechnical Users Bryan J. Urban Leon R. Glicksman, PhD Member ASHRAE Bryan Urban is a research assistant and PhD candidate in mechanical engineering and Leon Glicksman is a professor of mechanical engineering and architecture at the Massachusetts Institute of Technology, Cambridge, MA.