Double Skin Façade

Description

This project simulates the airflow inside a building's double-skin façade (DSF) using ANSYS Fluent. In a DSF, solar-heated air rises by buoyancy through a ventilated cavity, providing passive heating while assisting ventilation and cooling within the building. The 3D geometry, built in Design Modeler, is a rectangular cavity of 0.6 × 3.2 × 5 m, made up of an airflow duct and a glazed section that absorbs solar heat. It has a 0.2 m rectangular inlet at the base of the glass wall and a 0.2 m outlet near the top. Meshing in ANSYS Meshing produces 490,725 elements.

Methodology

The study evaluates the buoyancy-driven circulation set up inside the DSF cavity. Solar gain on the glazing is represented by a volumetric heat generation of 6,940 W/m³ applied to the glass section. The building walls are brick and lose heat by free convection to the interior, modeled with T = 300 K and h = 23 W/m²·K. Supply air enters the façade at 304.55 K and atmospheric pressure. To capture buoyancy, air density follows the ideal-gas law and gravity is set to 9.81 m/s².

Analysis

Post-processing delivers 2D and 3D contours of pressure, velocity, and temperature, along with 2D and 3D velocity vectors. The vectors show a clear upward flow through the cavity, confirming the buoyancy-driven ventilation that characterizes a double-skin façade.