Indeed, as a project matures, it becomes increasingly difficult, as well as costly, to make effective changes to the performance. In response to this need, KPMB LAB, the research and innovation group at KPMB Architects, has developed a basic energy modelling tool for internal use on projects. This article discusses how the tool works, how it relates to more comprehensive energy modelling software, and how it can be useful to an architect during concept and schematic design phases.