What are the acoustic performance capabilities of a standard curtain wall?

The acoustic performance of a standard curtain wall, which typically consists of an aluminum frame and standard double-pane insulated glass units (IGUs), is generally adequate for most commercial office environments. It can effectively reduce common exterior noises like traffic and wind. The performance is measured using ratings like Sound Transmission Class (STC) or Outdoor-Indoor Transmission Class (OITC), with higher numbers indicating better sound insulation. A standard system might achieve an OITC rating in the range of 28-32. However, for buildings in noisy urban environments, such as those near major highways in Jeddah or airports, this standard performance may not be sufficient. Fortunately, the acoustic capabilities of a curtain wall can be significantly improved. The most effective method is by modifying the glazing. Using laminated glass is a key strategy. Laminated glass consists of two or more layers of glass bonded together with a polyvinyl butyral (PVB) interlayer, which is very effective at damping sound vibrations, particularly in the mid-to-high frequency range. Further enhancements can be made by using different thicknesses of glass in the IGU (e.g., 6mm exterior pane and 10mm interior pane), as the different thicknesses disrupt a wider range of sound frequencies. Increasing the air space between the glass panes or filling it with a dense gas like argon can also contribute to better sound insulation. Additionally, ensuring high-quality, continuous seals and gaskets throughout the aluminum framework is critical, as any air gap can become a path for sound to travel.