IN ASTM MANUAL MNL 18, Moisture Control in Buildings, 2 Mark Bomberg and Cliff Shirtliffe, in their chapter "A Conceptual System of Moisture Performance Analysis," make the case for a rigorous design approach that "should involve computer-based analysis of moisture flow, air leakage, and temperature distribution in building elements and systems." In the Preface to the same manual, I state that one objective of Manual 18 is to help establish moisture control in buildings as a separate and essential part of building technology.