Retail buildings are responsible for approximately 18% of energy consumed by commercial buildings in the United States (EIA 2008). They offer a great opportunity for energy savings because retail stores have many similarities, and because large companies can implement successful energy efficiency strategies across their portfolios. Recognizing this potential, the U.S. Department of Energy (DOE) formed the Commercial Building Partnership (CBP) program to work with select companies in retail and commercial real estate to reduce energy consumption by 30% in existing buildings and 50% in new construction versus ANSI/ASHRAE/IESNA Standard 90.1-2004 (ASHRAE 2004a). The National Renewable Energy Laboratory partnered with Target under the CBP program to design and implement a retrofit of a SuperTarget in Thornton, Colorado. The result was a retrofit design that predicted 37% energy savings over ASHRAE Standard 90.1-2004, and 29% compared to existing (pre-retrofit) store consumption. Energy simulations of each efficiency measure played a key role in determining a mix of solutions that would provide the best value and yield the highest savings. The largest savings came from energy-efficient lighting and cooling systems, improved refrigeration, and better control of plug loads. The results of this effort will be carried forward to inform the retrofit of other stores across the nation. Other companies will also be able to use these results to achieve DOE’s energy efficiency goals.