The use of computers in the heating, ventilating, air-conditioning, and refrigeration,industries, although minimal until the mid-1960's, has been increasing rapidly in the last decade. Much of this increase can be attributed to two key factors: (1) the efforts of such organizations as ASBRAE, the National Bureau of Standards (NBS), and Automated Procedures for Engineering Consultants (APEC) in publicizing the benefits of computer analysis and (2) an increasing demand by building owners for more 'cost-effective design and operation of buildings and equipment. A still greater increase in the use of computers in the building industry is anticipated as a consequence of the world's emerging energy supply problem. Accompanying this rapid rise in the us~ of computers in the industry has ,been the appearancE:l of a large number of computer programs which are, in many cases, available to users other than the developer.