Experimental and numerical simulation study on hygrothermal migration of damaged envelope walls during wind-driven rain

Abstract

The optimal design of building envelopes, indoor environmental control, and energy efficiency are significantly impacted by damaged envelope walls. Cracks are crucial for accurately assessing the hygrothermal behavior of damaged walls, especially under the dynamic boundary of wind-driven rain (WDR). To evaluate the hygrothermal performance of envelope walls with cracks, we conducted experimental and simulated comparative studies on walls under the action of WDR. A capillary pressure model for high humidity environment was established. By analyzing field measurement results of damaged walls subjected to the WDR of Shenyang in 2022, we performed heat and humidity coupling numerical simulations of damaged envelope walls. The crack penetration depth, distance from cracks, and wall height were analyzed comparatively. Compared with the undamaged wall, the moisture content of crack depth under 36 mm (penetrating crack), 20 mm, 12 mm and 6 mm increased by 17.2%, 6.9%, 3.9% and 1.5%, respectively. Compared to the humidity distribution at 0.50 m, the relative humidity at 0.1 m, 0.2 m, 0.3 m and 0.4 m increased by 29.9%,27.6%,23.1% and 15.2%, the temperature changed by 1.20K,1.11K,0.72K,0.41K. The effects of various factors such as crack penetration depth, distance crack length, and wall height on the hygrothermal behavior of porous material building enclosures subjected to the WDR are derived. A theoretical basis is provided for the analysis and research of coupled hygrothermal transfer in porous buildings under the dynamic boundary of WDR.