The use of heat pumps for the heating and cooling of the Commonwealth Building, initiated in 1948, was a pioneering achievement in the western hemisphere. The theoretical conception of the heat pump was described in a neglected book, published in 1824 and written by a young French army officer, Sadi Carnot. Its practical application on a large scale is attributable to designers J. Donald Kroeker and Ray C. Chewning, building engineer Charles E. Graham, and architect Pietro Belluschi.
The integration of pump and turbine was the first of many to be installed in power-plant systems in the United States. It was the largest and most powerful in the world. As a "pump storage" unit in the Tennessee Valley Authority's system, it effected significant economies in the generation of electrical energy. The unit was designed by engineers of the Tennessee Valley Authority and the Allis-Chalmers Company. It was built by Allis-Chalmers.