Indoor laundry drying: Full-scale determination of water emission rate and impact on thermal comfort

To save energy, passive drying is encouraged by environmental agencies. Depending on seasons, climates and dwellings, laundry drying is performed indoors. Passive laundry drying is an indoor practice with high cultural variability. This work provides real-scale experimental data on water transfer to indoor environment and thermal impacts of laundry drying on rack. Representative laundries and drying practices are defined to validate a full-scale experimental methodology. Laundry and drying scenarios are explored using the 40-m³ experimental room IRINA. Among typical cotton and polyester laundries, cotton is selected as clothing of interest, with ca. 2000 g of water to be evaporated for specific laundry scenario. The simultaneous monitoring of water mass loss from laundry rack and humidity over the drying period allows for determination of water emission rate from laundry. During the first 2-hours of drying, water emission rate exceeds 100 g h⁻¹ (maximum 360 g h⁻¹.) Three different emission regimes over time are discussed in terms of water concentration gradient at the air and laundry interface. Consequences on indoor temperature are quantitated over drying. Initial relative humidity of indoor environment impacts the kinetics of water transfer and drives the thermal impacts: temperature drops from 0.5 to 3.8 °C are recorded. Based on these full-scale hygrothermal data, the impact of laundry drying on indoor thermal comfort is discussed. Two indoor comfort scenarios allow for assessing the magnitude of the impact of laundry drying. This work provides full-scale methodology with hygrothermal experimental datasets and a new insight on an impactful indoor practice.