The movement of heat throughout our built environment by transmission of radiation between surfaces is often overlooked in the operation, performance, and comfort of buildings. The temperature of a surface determines the amount of blackbody radiation it will emit, and thus controls the radiant exchange of heat in the environment. The heat exchange by radiation is important for systems and can dramatically influence the energy efficiency and the perceived comfort of a building. We discuss the physical mechanisms for measuring and understanding the heat transfer by radiation in buildings as well as the important connections to system performance and operation. The historical perspective on comfort, operation, and radiation is discussed. Finally, some novel concepts that take advantage of an understanding of radiant heat transfer potential are explored.