The Department of Energy released January 10 the third installment in a series of four 50 percent Advanced Energy Design Guides. The latest guide will help architects, engineers, and contractors design and build highly efficient retail buildings. The series, which support President Obama’s goal to reduce energy use in commercial buildings 20 percent by 2020, provides a practical approach for designers and builders of commercial buildings to achieve 50 percent energy savings compared to the building energy code used in many parts of the country.