Performance evaluation of a residential spaceconditioning system requires testing under the range of weather conditions normally encountered during a heating or cooling season. This paper describes the strategy developed for testing multiple heating systems in a single season. The strategy developed for two geographical locations (Washington, DC, and Chicago) includes criteria for defining the beginning and the end of the heating season, the most appropriate methods for partitioning the season, and minimum testing durations within each partition to ensure representative tests. A goodness-of-fit test was used to assess alternative methods of partitioning the heating season based on (1) average daffy outdoor temperatures during five recent heating seasons and (2) daffy heatingloads during the heating season for the test reference year for each location. Results indicate that representative tests of two heating systems can generally be conducted within each half of the heating season by alternating the system to be tested on a weekly flip-flop basis. Guidelines are provided for choosing a time near midseason to install new systems for testing such that outdoor design temperatures are likely to be encountered during both halves of the heating season.