As an alternative approach to evaluate the unit heating load for apartment houses, we newly developed and proposed unit building method. The new method, which calculates the heating load of an apartment building as a whole, conceptually corresponds to integral analysis of building heat loss, while the existing unit apartment method to differential analysis. Four typical building models of Korean-style apartment house and two dynamic load calculation programs were selected to validate the present method under realistically imposed conditions. Eight sets of unit heating load calculated respectively by unit building and unit apartment methods showed excellent agreements regardless of building model and simulation program. It is expected that the unit building method can take the place of the unit apartment method due to fewer modeling assumptions as well as less computational efforts. Additional calculations to investigate the effects of various parameters on unit heating load yield good consistencies with known facts, and re-confirm the validity.