Technology — from sophisticated computer modeling to advanced windows that actually open — will help the newest building at the U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) be one of the world's most energy efficient offices. Scheduled to open this summer, the 222,000 square-foot RSF will house more than 800 staff and an energy efficient information technology data center. Because 19 percent of the country's energy is used by commercial buildings, DOE plans to make this facility a showcase for energy efficiency.