ASHRAE has published a new standard describing a methodology to apply building energy modeling throughout the design process. ASHRAE Standard 209-2018, Energy Simulation Aided Design for Buildings except Low Rise Residential Buildings, defines minimum requirements for providing energy design assistance using building energy simulation and analysis. It defines consistent energy modeling procedures to quantify the impact of design decisions when they are being made. The standard applies to new buildings, major renovations and additions, and defines nominal requirements for using modeling to support integrated design efforts. This new standard will be useful to building owners, architects, government agencies and many others who want their projects to benefit from the use of simulation.