The report contains a comprehensive review of the work carried out under RP-254. The objective of the project was to experimentally measure moisture transfer through openings that exist between spaces with different humidities and temperatures and also to measure the moisture transfer to ducts carrying conditioned air through unconditioned spaces. These data were then used to develop mathematical relationships for engineering application.

This report contains six parts: a literature review which was conducted early in the project, a description of the experimental facility used, a description of the experimental program and presentation of the results, a presentation of the theory involved, conclusion and applications for engineering purposes, and an appendix with complete documentation of all the experimental data. Those who are mainly concerned only with the applications of the results may wish to go directly to the conclusions and application section.