The International Space Station (ISS) Temperature and Humidity Control (THC) system has been designed with the intent of supplying the air cooling needs of various elements from the U.S. Lab heat exchanger assembly. Elements without independent air cooling capability are known as “parasitic” elements; these are Node 1, the Cupola, and the Mini Pressurized Logistics Module (MPLM). Analysis results are presented which show expected temperatures in the MPLM, and Node 1, as various heat loads are present in the respective elements.Analyses within this paper are coordinated with the results obtained from the Development Test of the complex USL/Node 1 integrated ducting system. This test was conducted in the summer of 1995, at the McDonnell Douglas test facility in Huntington Beach, California. The test results indicate that when one USL heat exchanger assembly is operating, the air flow rates provided to the parasitic environments are lower than necessary to accomplish satisfactory cooling under high parasitic heat load conditions. Operating in the “Enhanced Mode”, wherein the second cabin air fan is also activated, is shown to result in acceptable cooling for the parasitic elements under all conditions.