What acoustic performance targets and glazing strategies should specify curtain wall for urban noise sites?

Urban noise mitigation through curtain wall design starts with setting clear acoustic targets aligned to the building’s function (e.g., office, hotel, residential). Typical performance metrics are weighted sound reduction index (Rw) or Sound Transmission Class (STC); for office spaces in noisy urban environments, specify Rw values above 40–45 dB for façade units, and higher for sensitive uses. Glazing strategy is pivotal: use laminated glass with viscoelastic acoustic interlayers, asymmetric multi-pane IGUs with different glass thicknesses to break resonance, and increased cavity depth to improve low-frequency attenuation. Triple glazing can add performance but increases weight and frame depth; designers often achieve efficient results with high-performance double glazed units combining laminated layers and gasketing. The curtain wall frame must be airtight and include acoustic seals and acoustic gaskets designed to maintain performance after movement. Avoid rigid mechanical fixings that transmit sound paths; use resilient glazing tapes and isolation mounts where necessary. Pay attention to ventilators, operable windows, and façade penetrations; acoustic louvers and attenuators may be required to preserve façade performance where ventilation is needed. Incorporate whole-assembly acoustic testing or accredited lab reports rather than glass-only figures, and consider field testing to verify installed performance in situ. Integrate acoustic targets into early design decisions because achieving high sound reduction often requires increased IGU thickness, heavier framing, and trade-offs with daylighting and thermal performance that must be resolved holistically.