Assessing ventilation cavity design impact on the energy performance of rainscreen wall assemblies: A CFD study

Abstract

The impact of the ventilation cavity design on the energy performance of the rainscreen wall assembly was numerically investigated in CFD. The ventilated cavity design parameters considered were the cladding material type (i.e. Fibre cement, brick, and metal cladding), the sheathing membrane emissivity coefficient (i.e. 0.1–0.9), the ventilated cavity height (i.e. 1H and 2H) and the air gap width (i.e. 13 mm–50 mm). The CFD model was validated with experimental data and a dynamic simulation for a typical hot day and cold day is performed for a timestep interval of 5 min. The heat flux through the wall assembly was compared amongst the design alternatives. For the range of parameters considered, the ventilated cavity construct with brick cladding, sheathing membrane emissivity of 0.1, one-storey ventilated cavity, and 13 mm air gap width minimized the heat loss for a typical cold day. However, ventilated cavity construct with brick cladding, sheathing membrane emissivity of 0.1, one-storey ventilated cavity, and 50 mm air gap width minimized the heat gain for a typical hot day.