For the last two decades most professional architectural and engineering associations have encouraged their members to embrace an integrated design approach to improve and minimize the energy flows through buildings, cities and the broader ecosystem. While the integrated design approach often is portrayed as relatively novel approach, the reality is that it is only since the rise of professionalism in the Western world that the building industry developed a disjointed approach to energy design in the built environment. Previously the professions of architecture and engineering were intertwined, and the architect-engineers of antiquity, the Renaissance and the Enlightenment still can serve as role models for how building industry professionals can take a unified approach to design even considering the complexities of modern building techniques. This paper attempts to provide a brief historical review of the integrated approach to energy design that many architect-engineers took before the industrial revolution.