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

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.

Automated summary

The impact of ventilation cavity design on the energy performance of rainscreen wall assembly was investigated numerically in CFD, considering various parameters such as cladding material type, sheathing membrane emissivity coefficient, ventilated cavity height, and air gap width. The CFD model was validated with experimental data and simulations were performed for both hot and cold days. Different design alternatives were compared based on heat flux through the wall assembly, showing that certain ventilated cavity constructs can minimize heat loss on cold days and heat gain on hot days.