Study of interior hygrometry profiles for the hygrothermal assessment of social housing envelopes in humid temperate climates

The building sector has focused on energy efficiency to promote sustainable development. However, incorporating energy efficiency measures in buildings usually affects their hygrothermal performance and can cause condensation and mold growth in their envelopes. These phenomena are related to the indoor climate, the enclosure setup, and the outdoor climate, so properly characterizing these parameters is fundamental for making hygrothermal assessments. From this perspective, the indoor climate is usually defined based on hygrometry classes or profiles, such as those in the ISO13788, EN15026, WTA, and DIN4108 standards. These standards have different limit values that seek to reflect the practices and cultures of use for buildings. The novelty of this research is to make new indoor hygrometry profiles based on post-occupational measurements. The indoor and outdoor humidity and temperature of 67 social housing units were monitored to build the new indoor hygrometry profiles, with 74,440 indoor and 4089 outdoor records. The excess indoor humidity was determined from these parameters, and the distribution of indoor variables using the outdoor temperature was analyzed. Subsequently, three types of new indoor hygrometry profiles were made that link outdoor temperature to excess indoor humidity, indoor relative humidity, and indoor air temperature. To test the new profiles, a comparative analysis of the hygrothermal performance of a built element was made using the WUFI Pro 6.4 software (168 simulations), considering the profiles of the ISO13788 standard and those developed in this study. The results show indoor environmental conditions are outside commonly accepted comfort ranges or more critical conditions from the hygrothermal point of view, with mean temperatures of 17 degrees C and relative humidities exceeding 80 % during 33.1 % of the monitored timespan. The results also show that the profiles developed in this study are more rigorous and properly reflect the indoor climate of the studied homes than the international standards commonly used. This research paves the way for new specific studies in similar climate conditions.