As originally developed, solar load ratio correlations for performance analysis of passive heating systems were intended for use only with a constant thermostat setpoint. The thermostat setpoint used in the method may be adjusted to account for the effect of heating from internal sources, but setback or shutdown strategies that are frequantly employed in both residential and commercial buildings were not allowed. A procedure for approximating the effect of various control strategies through use of an equivalent constant thermostat setpoint, T/sub ec/, has recently been developed at Los Alamos National Laboratory. The value of T/sub ec/ depends on the level and duration of thermostat settings used during the diurnal cycle and on the characteristic time constant is a function of the diurnal heat capacity of the building and its loss characteristics. The method described in this paper has been applied to a variety of passive solar buildings in two distinct climatic regions and was found to yield good accuracy when compared with detailed thermal network calculations.