A program to improve indoor air quality in Providence, RI, triple-deckers and single-family homes was begun in 2001. Temperature and humidity data logging equipment was placed in playrooms, bedrooms, and basements in 71 dwelling units in 37 buildings from winter 2001 to 2004. Indoor vapor pressure values were calculated from indoor and outdoor temperature and humidity measurements for each measurement location. The difference between indoor and outdoor vapor pressure—the vapor pressure excess—was the principal tool of analysis. Factors that influence the quality of the results are discussed, including: calibration of the equipment, reliability of outdoor weather measurements and continuity of the indoor measurements. Findings from this study are viewed within the framework of ISO 13788, which permits a vapor pressure excess comparison of these buildings to European residential buildings. The vapor pressure excess findings from the study are discussed with regard to

• The effect of humidity in vertically-stacked dwelling units
• Wetness and dryness in basements
• Conditions in the playroom compared to the bedroom
• Assessment of standard means of representation

This paper provides the analysis of three years of data. An earlier paper presented in Buildings IX provided the results from five months of data. The data are presented here in a format appropriate for comparison to other similar temperature and humidity data.