There are many moisture-related problems and topics in the field of buildings. In this review, the past research trend in the field of moisture in Japan is first overviewed by examining the activities reported in the AIJ symposium on thermal environment. The theme of the symposium held every 10 years indicates the research trend, i.e., the research until the year 1990 established the theoretical basis of heat and moisture transfer; then, until the year 2000, the established theory was developed to be applied in practice, and until the year 2010 the results obtained so far were presented to a wide range of occupants and end users.

The indoor humidity and the accompanying problems are closely related to the fact that most of the materials constituting the building are porous, and thus absorb water vapor. Therefore, the important topics of moisture research emphasizing the heat and moisture transfer in porous building materials are described, i.e., heat and moisture transfer in porous material and method of analysis, condensation and mitigation of humidity change, freezing-thawing, mold and wood-rotting fungi, health and comfort, conservation of cultural properties, etc.

Finally, the challenges and prospects are presented.