An insufficient amount of measured data is available on actual indoor humidity levels in U.S. households, making it difficult to design durable homes. This research project has collected 1 full year of indoor temperature and humidity data for a sample of 60 homes across three different climate regions—the hot and humid Southeast (Zone 2), the cold Northeast (Zone 5), and the marine Northwest (Zone 4).

This research was in direct support of the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), Inc. Standard 160, Criteria for Moisture-Control Design Analysis in Buildings. A research methodology was developed with assistance from Oak Ridge National Laboratory (ORNL), a subcontractor and member of Standing Standards Project Committee 160 that acted in an advisory role. The monitoring protocol involved three site visits to each home to perform tasks such as collecting basic house and equipment characteristics, installing data loggers, performing testing to quantify envelope leakage and duct leakage, and collecting data recorded by the loggers. Data compiled in the field tests were analyzed to identify the potential relationships between certain household characteristics and the measured internal humidity levels.

This report presents significant findings from the study. Correlations between indoor moisture levels and climate, occupant density, and house characteristics are the focus of the results. Conclusions and recommendations for indoor moisture management or future research needs are also discussed.

Supplemental report for the moisture field data analysis (PDF, 22 MB)
Moisture study data (Zipped file of Microsoft Access Database, 108 MB)