The National Renewable Energy Laboratory's (NREL) mission is to advance the U.S. Department of Energy's and the nation's goals in the areas of energy security, environmental quality, and economic vitality. From the beginning, NREL recognized that its new Research Support Facility (RSF) represented a unique opportunity to demonstrate the state-of-the-art in energy-efficient, cost-effective commercial office design, construction, and operation. Today, buildings use roughly 40% of total primary U.S. energy consumption (22% residential, 18% non-residential); energy consumption in this sector is projected to grow by 25% in the next two decades. The RSF is intended to prove that significant gains in energy efficiency can be realized cost effectively in commercial buildings with available technologies if careful attention is paid to project energy goals, the delivery process, and integrated design. We examine the details of how computer simulation tools were used to help design the RSF and what capabilities the project required of those tools. We also present a portrait of how setting an absolute whole-building energy consumption target changes the role of energy modeling. Several teams were involved in the competition phase; however, we focus on the activities of the design-build team that was awarded the contract.