Design teams often use energy modeling as an accounting or code compliance tool to establish that minimum requirements are met. Used in this way, significant opportunities to inform and improve building design are overlooked. Properly used, energy modeling can provide outputs that optimize a building’s energy consumption, reduce life cycle costs, and even reduce first cost. This paper will review how and when design teams typically use energy modeling in each design phase (concept phase, schematic design, design development, and construction documentation) and describe strategies for each phase that can lead to lower energy use buildings.