This report is the first in a series and details the results accomplished under the following tasks: (1) evaluation of existing passive solar calculation methods, (2) BLAST/DOE-1 program interface and comparison with BR-202, and (3) development of analytic relationships between the thermal balance and weighting factor techniques. The various methods available for use in thermal load analysis are presented with detailed information on algorithms used in the thermal balance and weighting factor techniques. (MOW)