Coupled heat and moisture transfer in walls featuring moisture-buffering materials and ventilating layers: An Experimental study

The moisture performance of building envelopes largely depends on the building materials, construction techniques, and exposure loads from the indoor and outdoor regions. A ventilated air interlayer placed in a wall can help dehumidify the wall and indoor air. This paper presents an experimental study of the heat, air, and moisture variations within the envelope wall of a chamber featuring different air interlayer settings under real outdoor air conditions during the summer of 2020 in Shanghai, China. Self-developed humidity-controlling building materials were applied to the inner building envelope. Temperature, humidity, wind velocity, and heat-flow sensors were placed at different positions in the middle of the wall. These parameters were measured and recorded in real-time under three working conditions: humidification, dehumidification, and ventilation. The experimental results show that under the ventilation working conditions, moisture content of 0.52 kg can be removed after a 2-h air layer ventilation, which can benefit the design strategy for the humidification and ventilation of dehumidification walls.