Presents a complete formulation of the heat balance method in a form suited to calculating cooling loads. The method was developed under ASHRAE research project RP-875. Presents the modelling assumptions in the heat balance method and develops a general model capable of representing the features of diverse building spaces as the basis for the method. Presents the mathematical foundation of the method along with a pseudo-code description of the solution technique. Includes examples showing the uses of the method.Units: SIKEYWORDS: year 1997, Cooling load, calculating