Public building air conditioning systems, which use constant and varying heat and cooling loads, are compared and investigated. Experiments indicated that constant temperature controls based on outside air temperature alone were inefficient. Ventilating a building with outside air and the methods of doing so are cited as being the most economical and efficient. Methods of calculating the thermal input and response of buildings are given. The influence of window treatments, air conditioning system sizes, building weight, construction, and designs are compared in conjunction with naturally ventilated and fully air conditioned environments. Diagrams and comparative charts are included. (TG)