This chapter identifies the concerns of major national institutions – governmental, professional, and industrial. It reviews the most important manifestation of these national concerns from the authors' point of view – the promulgation of building energy performance standards. Professional bodies with an interest in energy and buildings have played important roles on the national scene. The design professions have been particularly active on behalf of their members. International agencies such as the United Nations had been involved in the sponsorship of work related to the thermal performance of low cost housing in underdeveloped countries. The four main environmental factors which affect one's sensation of thermal comfort are air temperature, radiant temperature, humidity, and air movement. Many attempts have been made to integrate various combinations of these factors into a single index of thermal comfort. Air temperature alone is still the most valuable guide to thermal comfort.