Indoor Humidity Loads and Moisture Production in Lightweight Timber-frame Detached Houses

Abstract

In this study, the indoor humidity loads in 101 lightweight timber-frame detached houses occupied by single families have been measured and analyzed. The temperature and relative humidity (RH) are measured at one-hour intervals over one-period in bedrooms, living rooms, and outdoors. Ventilation rates are measured with a passive tracer gas technique. Based on temperature and RH measurements, the difference between indoor and outdoor air absolute humidity is calculated. For hygrothermal design, the maximum moisture supply at the 10% critical level in the houses with low occupancy is +4 g/m3 during the cold period (Tout≤+5°C) and +1.5 g/m3 during the warm period (Tout≥+15°C). Between these outdoor temperature values the moisture supply changed linearly. Different moisture supply levels and their dependence on outdoor temperature are given. An average moisture supply and moisture production values are calculated for the use of indoor climate simulations. A moisture supply design curve is given for the humidification case with a set point of 25% indoor RH.