Full Description

Moisture drying, wetting, and redistribution in wall components can be affected by several factors, such as wind speed and direction, solar gain, wind-driven rain, indoor and outdoor humidity, and air infiltration and exfiltration. One of the main reasons air cavity ventilation is used in envelopes is to facilitate the moisture control strategy. A computational model that combines a detailed Computational Fluid Dynamics (CFD) model for the air transport in the cavity with a Heat-Air-Moisture (CFD-HAM) model is a useful tool to provide an accurate hygrothermal performance assessment of a rain screen wall. However, coupled CFD-HAM models can be computationally expensive and time-consuming. Recently, a simplified empirical model that accounts for the effects of wind and solar radiation on cavity ventilation was developed. In this study, thissimplified empirical model is used to study the hygrothermal performance of a wood frame rain screen wall in British Columbias coastal climate. In addition, the simplified empirical models performance is compared against three other existing models: 1) considering the cavity as still air, 2) an already existing empirical model, and 3) constant ACH values of 100ACH and 200 ACH. Results show that all models provide a similar result during wetting seasons. The wall system with a still-air cavity exhibits the highest moisture content on plywood followed by the empirical model used from the literature. The newly developed empirical formula and the 100 ACH and 200 ACH give a similar estimation in most cases of the simulation period. Key words: ACH, cavity ventilation, hygrothermal performance, moisture content, rain screen wall.

Citation: Thermal Buildings XIV 2019

Product Details

Published: 2019 Number of Pages: 8 Units of Measure: Dual File Size: 1 file , 6.3 MB Product Code(s): D-Bldgs19-046