Incorporating quantitative tools throughout each stage of the design process empowers architects to evaluate and understand the complex environmental implications of their design decisions and to make deliberate, informed choices. We will discuss the rapidly expanding arsenal of tools available to designers, including energy modeling, thermal modeling, LCA, and solar analyses. The presentation will focus primarily on how to deploy thermal and energy modeling early in the design process for both preservation and new construction projects. We will also provide examples of effective strategies to integrate these tools into the architects' design process at critical moments and examine how in-house analyses can complement and enhance the architect-consultant relationship to drive significant improvements in building performance and life cycle impacts.