General Assist Technical Reference

Outdoor Unit Noise and Council Requirements

Understanding noise assessment locations, installation effects and acoustic treatment
Key point: Outdoor-unit sound data measured close to the equipment should not automatically be compared directly with a council noise limit. Council requirements are generally assessed at a nominated property boundary or noise-sensitive receiver, using the methodology specified by the relevant authority.

1. Where council noise is normally assessed

In practical terms, most brands - if not all brands - in this capacity may not meet a council noise requirement if the requirement is applied to a measurement taken only one metre from the outdoor unit.

Council requirements are typically assessed at the property boundary or at the nearest noise-sensitive receiver, such as a neighbouring bedroom or residence. Because sound reduces with distance, the noise level at the assessment location may be lower than the value measured close to the outdoor unit.

Important: The exact assessment location, time period, corrections and measurement methodology vary between councils and jurisdictions. These must be confirmed against the specific council requirement for the site.

2. Installation environment can increase noise

Compliance is highly dependent on the installation environment. Published sound data does not account for every site condition.

Hard or confined surfaces can reflect sound and increase the measured result. Particular care should be taken where an outdoor unit is installed:

  • Between concrete or masonry walls
  • In narrow side passages
  • Inside alcoves or partially enclosed areas
  • Close to corners
  • On structures that can transmit vibration
Site conditionPotential effect
Hard walls or floorsSound reflections can increase perceived and measured noise.
Narrow passage or alcoveReflections and restricted sound dispersion may amplify noise.
Poor mounting or rigid structureStructure-borne vibration may transmit into walls, floors or neighbouring spaces.
Unit close to boundary or bedroomLess distance is available for sound attenuation.

3. Acoustic barriers and screening

At this stage, there is no specific product or accessory that can be supplied which will reliably guarantee that an outdoor unit will meet a particular council noise condition.

If an acoustic barrier or screening solution is required, it must be designed so that the outdoor unit can maintain its required:

  • Air intake and discharge airflow
  • Installation clearances
  • Service and maintenance access
  • Heat rejection and operating performance
Do not enclose or restrict the outdoor unit. Any barrier or screen must allow the unit to breathe and must comply with the installation manual. Restricting airflow can reduce capacity, increase operating pressure or temperature, affect reliability and lead to faults.

4. Recommended next steps

  1. Confirm the council assessment point and methodology. Establish where noise will be measured and what adjustments or criteria apply.
  2. Review the proposed outdoor-unit location. Maximise separation from property boundaries, neighbouring windows and other noise-sensitive receivers.
  3. Avoid reflective locations. Where possible, avoid corners, narrow passages and alcoves that can increase reflected sound.
  4. Consider re-orientation or relocation. Direct discharge and the main sound path away from the most sensitive boundary or receiver where practical.
  5. Check mounting and vibration isolation. Ensure brackets, slabs, anti-vibration mounts and fixings are appropriate and do not transmit unnecessary structure-borne noise.
  6. Use an acoustic consultant where required. If screening or a barrier is necessary, engage a suitably qualified acoustic consultant to design a solution that achieves the required attenuation without compromising airflow or service access.

5. Information required for further guidance

For further assistance with unit placement or available acoustic documentation, provide:

  • Proposed outdoor-unit location
  • Site plan and/or elevations
  • Distance to the property boundary and nearest sensitive receiver
  • The council's nominated measurement position
  • Any specific council noise condition or acoustic report
Outcome: Noise compliance should be assessed at the location and using the method nominated by the relevant council or authority. Good outdoor-unit placement, suitable vibration isolation and professionally designed acoustic treatment can materially improve the result without compromising system operation.
General Assist Technical Reference