HDAcoustic application icon HDAcoustic HVAC Plenum Acoustics Calculator

HDAcoustic is a practical desktop tool for estimating the acoustical performance of plenums and air handling units (AHUs) in HVAC systems. Starting from source sound power levels in the standard octave bands, HDAcoustic calculates sound power levels at each opening in the plenum or AHU, as well as radiated (breakout) sound power levels, based on the geometry and construction of the enclosure.

Standard absorption and transmission-loss (TL) coefficients for common plenum and AHU constructions are pre-loaded, so you can get results immediately. When manufacturer data or measured values are available, HDAcoustic lets you enter your own custom coefficients for any construction — giving you accurate acoustical estimates for virtually any plenum or AHU configuration.

Multiple sound sources and multiple openings are fully supported, making HDAcoustic suitable for real-world systems with complex geometries.

KEY FEATURES

  1. Accepts source sound power levels in the eight standard octave bands (63 Hz through 8 kHz) for one or more noise sources.
  2. Estimates sound power levels at plenum or AHU openings based on opening size, plenum geometry, and absorption characteristics of the enclosure walls and lining.
  3. Estimates radiated (breakout) sound power levels through plenum and AHU walls using transmission-loss coefficients for the enclosure construction.
  4. Pre-loaded library of standard absorption and TL coefficients for common plenum and AHU constructions — use immediately without additional data entry.
  5. Fully user-customizable coefficients — enter your own octave-band absorption and TL values from manufacturer data or field measurements for any construction type.
  6. Supports multiple sound sources and multiple openings within a single plenum or AHU model.
  7. Full IP and SI unit support — toggle between ft / ft² and m / m² with a single click; all geometry inputs and results convert automatically.
  8. Clipboard copy — exports all inputs and results as tab-delimited text for pasting directly into spreadsheets or project reports.
HDAcoustic plenum geometry inputs and octave-band results screenshot

INPUTS

HDAcoustic accepts the geometrical and acoustical parameters that describe the plenum or AHU and its noise sources:

  • Source Sound Power Levels — octave-band sound power levels (dB re 1 pW) for each noise source in the system (fan, coil, damper, etc.)
  • Plenum / AHU Dimensions — length, width, and height of the enclosure (ft or m)
  • Opening Sizes — area of each supply or return opening (ft² or m²) through which sound is transmitted
  • Wall / Lining Construction — absorption coefficients (α) per octave band for the interior surfaces, selected from the pre-loaded library or entered as custom values
  • Transmission Loss — TL values (dB) per octave band for the plenum or AHU wall panels, selected from the pre-loaded library or entered as custom values
  • Number of Sources — one or more simultaneous noise sources inside the enclosure
  • Number of Openings — one or more openings for which sound power levels are computed independently

RESULTS

HDAcoustic reports octave-band and overall sound power levels for each of the following:

  • Sound Power Level at Each Opening — octave-band PWL (dB) transmitted through each supply or return opening into the downstream duct or space
  • Radiated Sound Power Level — octave-band PWL (dB) radiated (broken out) through the plenum or AHU walls into the surrounding space
  • Overall (dBA) Levels — A-weighted sound power levels for quick comparison against HVAC acoustical criteria
View more app screenshots here.

System Requirements

  • Windows 10 or Windows 11
  • .NET 8 Runtime (included in installer)
  • 50 MB disk space

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