What causes architectural façades to whistle?
When wind passes across the elements of a façade, it can cause a whistling, humming, or droning noise.
Topics covered:
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Why wind noise occurs on façades.
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The design factors that influence wind noise (free area ratio, blade angle, material thickness, and perforation geometry).
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Methods to prevent wind noise, including CFD simulations and wind tunnel testing
Why does this happen?
As wind passes through the gaps, blades, or perforations of façades, small pressure variations form around these openings. When these air pressures line up at certain frequencies, they can amplify one another, producing a whistling, humming, or droning noise.
Several design factors influence the likelihood of wind noise: free area ratio, blade angle, material thickness, and the pattern or geometry of perforations. The combination of these determines how airflow behaves across a façade, influencing both aerodynamic performance and acoustic effects.
Although the effects are often subtle, unwanted noise can quickly become a comfort and design issue for both building occupants and neighbouring properties.
The challenge lies in finding the right balance: maintaining adequate ventilation and aesthetic intent without allowing the potential for whistling.
How can you prevent wind noise?
Wind noise can be prevented by using desktop simulations, such as CFD (Computational Fluid Dynamics). CFD can model how wind moves around and through building elements, allowing architects to modify their design in the early stages of a project.
Other methods of testing for wind noise include wind tunnel testing. In wind tunnel testing, scale models or full-size components are exposed to controlled airflows to observe how they behave in real conditions. This allows engineers to see how building elements respond to natural, unsteady wind, giving designers greater confidence in how they will perform in real conditions.