As the UK accelerates its path to net-zero carbon emissions, the transition from fossil fuels to low-carbon heating technologies is both urgent and inevitable. Air source heat pumps (ASHPs) have emerged as one of the most promising solutions, offering an energy-efficient way to heat homes while significantly cutting greenhouse gas emissions. However, amidst the growing public and political debate around this technology, concerns about noise have become a frequently cited barrier to widespread adoption.
The Noise Debate: Politics and Misinformation
Unfortunately, the conversation around ASHPs has become increasingly politicised, with conflicting claims circulating across media platforms and online forums. One of the most persistent myths is that ASHPs are inherently noisy and disruptive to both homeowners and neighbours.
While some individuals have experienced genuine noise issues, the broader narrative is often shaped by misinformation, outdated examples, or poor installations. It is essential to approach this topic with nuance, acknowledging isolated issues while recognising that modern, well-installed heat pumps can be quiet and unobtrusive.
When Noise Problems Do Occur
Some people have indeed experienced genuine noise issues with heat pumps. These problems are often associated with heat pumps that aren’t functioning correctly due to poor installation, inadequate maintenance, or mechanical faults. Many older models didn’t benefit from the noise reduction technologies that have now become standard in heat pumps for the domestic market. There have also been cases of inappropriate installation positions, e.g. outside of bedroom windows or where vibration from the unit gets transferred into the building structure.
In most cases, noise is not a fundamental flaw of the technology but rather a result of improper setup or outdated equipment.
UK Planning Rules: What’s Permitted
Under current UK permitted development rights, homeowners can install an ASHP without planning permission, provided the system complies with specific criteria. One key requirement is that the noise level does not exceed 37 dB(A) at 1 metre from the nearest habitable room window of a neighbouring property.
This noise level is typically calculated using data supplied by the manufacturer, and it is normally the installer’s responsibility to perform this assessment.
When Planning Permission is Required
In some cases, heat pumps cannot be installed under permitted development rights, such as in conservation areas, or when the noise level exceeds the 42dB threshold. In these circumstances planning permission is needed and the noise assessment becomes significantly more rigorous, often resulting in stricter limits.
This normally involves a professional noise consultant conducting a 24-hour noise survey to establish the existing background noise level. The allowable heat pump noise is set in relation to this baseline, typically needing to not exceed the background level, or be 5 or 10dB lower (this varies from one local authority to another).
Noise Mitigation Strategies
If the projected noise level exceeds the acceptable threshold, then mitigation measures must be employed to reduce the heat pump noise accordingly. Where no alternative installation location is available and there is no option to specify a quieter running unit, noise control may be the only option.
In some cases an acoustic screen around the unit may be sufficient, but this needs to block the line of sight of the receptor to be effective (i.e. this is generally not feasible where the receptor overlooks the heat pump).
Alternatively, purpose-built acoustic enclosures are available which fully enclose the unit and include attenuated ventilation openings. These enclosures must be carefully engineered to allow adequate airflow without impairing the heat pump’s performance. They are generally expensive and significantly larger than the unit itself.
The Path Forward
As the UK embraces low-carbon technologies, it’s vital to separate fact from fiction. Noise concerns around air source heat pumps are real for a minority, but they are often solvable and should not overshadow the broader environmental benefits these systems offer.
Modern ASHPs are quieter, more efficient, and more reliable than ever. By focusing on proper installation, maintenance, and considered acoustic assessments, we can ensure these technologies are both sustainable and neighbour-friendly.