ISO 12354-4:2017

Overview

ISO 12354-4:2017 - Building acoustics specifies a calculation model to estimate the sound power level radiated by a building envelope caused by airborne sound inside the building. The standard uses measured inside sound pressure levels together with measured transmission data for elements and openings (walls, roofs, façades, ventilations, etc.) to derive substitute point sources that represent the building envelope. These radiated sound power levels are the basis for calculating the exterior sound pressure level at a chosen distance when combined with propagation attenuation.

Key scope boundaries:

• Covers estimation of indoor sound transmission to the outside (building envelope radiation).
• Excludes prediction of indoor sound pressure from interior sources and detailed outdoor sound propagation (though Annex E gives a simplified approach for simple propagation cases).

Key topics and technical requirements

• Calculation model: Principles for converting measured indoor sound pressure and element transmission data into sound power levels of substitute point sources representing segments of the building envelope.
• Substitute point source determination: How to segment the envelope and compute equivalent point-source sound power.
• Directivity correction (Dc): Adjustments for directional radiation of segments toward a reception point.
• Element performance metrics: Use of sound reduction index (R), element normalized level difference (Dn,e) and insertion loss from laboratory or field measurements.
• Diffusivity term (Cd) and inside sound pressure level (Lp,in): Definitions and their role in calculations (e.g., Cd ≈ –6 dB for a diffuse field).
• Limitations and accuracy: Guidance on expected accuracy, restrictions, and need for correct input data.
• Informative annexes: Symbols (A), interior sound field (B), sound reduction index (C), directivity (D), simplified exterior level prediction (E), single-number rating application (F), and a worked calculation example (G).

Applications and who uses it

ISO 12354-4:2017 is designed for:

• Acoustic consultants and building acoustics experts performing façade and façade-element assessments.
• Building designers and façade engineers assessing how interior noise radiates outdoors.
• Regulatory authorities and planners integrating element-based acoustic performance into noise impact assessments.
• Manufacturers and test laboratories who supply element transmission data (ISO 10140, ISO 16283 referenced methods). Practical uses include pre-construction design comparisons, compliance checks, façade improvement studies, and feeding sound power data into external propagation models or noise mapping tools.

Related standards

• ISO 12354 series (other parts on airborne and impact noise)
• ISO 10140-1 (laboratory sound insulation measurement)
• ISO 16283-3 (field measurement of façade airborne insulation)
• ISO 7235 (insertion loss for ducted elements)
• ISO 9613-2 (outdoor sound propagation methods - commonly used to combine with ISO 12354-4 results)

Using ISO 12354-4:2017 yields a consistent, element-based approach to quantify how indoor noise radiates outdoors, enabling objective evaluation of building acoustic performance and better integration with outdoor noise prediction tools.