Hygrothermal investigation of lightweight steel-framed wall assemblies in hot-humid climates: Measurement and simulation validation

In recent years, lightweight steel-framed (LSF) constructions are considered sustainable and widely used worldwide. However, the LSF wall assemblies have the risk of durability failure in hot-humid climates. This study conducted fundamental research on the hygrothermal performance of LSF wall assemblies by characterizing the hygrothermal responses, modelling and validating the simulation models under hot-humid climatic conditions. Through measuring the relative humidity and temperature of various positions inside, four typical and full-scale LSF wall assemblies were tested thoroughly and comparatively on two room-like test cubes in Guangzhou, a hot-humid city in China. It was found that the ventilated rainscreen provided better hygrothermal responses of the wall assemblies than the face-sealed cladding; the closed-cell external insulation could significantly improve the hygrothermal responses of the wall assemblies with stucco cladding; generally, wall assemblies with ventilated rainscreen and external insulation exhibited the best hygrothermal response in a hot-humid climate, followed by wall assemblies with ventilated rainscreen, wall assemblies with face-sealed cladding and external insulation and wall assemblies with face-sealed cladding. Furthermore, the measured data were used to model and validate the simulation models of the four typical wall assemblies in software. It was shown that hygrothermal simulation is sufficient for evaluating the long-term hygrothermal performance of LSF wall assemblies in hot-humid climates, and relatively conservative settings are necessary for evaluating cases with great uncertainties. Overall, this study could lay a foundation for better assessing and improving the hygrothermal performance, durability and sustainability of LSF buildings in hot-humid climate regions worldwide.

Automated summary

In hot-humid climates, lightweight steel-framed (LSF) constructions face durability challenges. A study on LSF wall assemblies found that ventilated rainscreen performed better than face-sealed cladding, and external insulation improved hygrothermal response. Overall, ventilated rainscreen and external insulation showed the best performance in hot-humid climates. Simulation models are useful for evaluating long-term performance, with conservative settings for uncertain cases.