Air Source Heat Pumps: Noise, Planning & How to Reduce It

In areas with moderate climates, heat pumps can provide a more environmentally friendly alternative to traditional heating and cooling systems such as gas boilers and conventional air conditioning.

An air source heat pump extracts heat from the outside air and transfers it into your home. You can use the heat generated for radiators, hot water, underfloor heating, and warm air systems.

Many air source heat pumps can also provide cooling during the summer months, making them a versatile solution for year-round temperature control. However, depending on the location and installation, you may need a heat pump noise survey to meet local planning or environmental noise requirements.

Are air source heat pumps environmentally friendly?

Air source heat pumps are generally considered a lower-carbon alternative to conventional fossil-fuel heating systems. Rather than generating heat by burning gas or another fuel, they extract naturally occurring heat from the air.

The system does, however, require electricity to operate. The environmental impact therefore depends partly on the electricity used to power the heat pump, as well as the system’s efficiency.

For homeowners looking to install an air source heat pump, environmental performance is only one consideration. Noise is another important factor, particularly where the outdoor unit is located close to neighbouring properties.

How much noise do air source heat pumps produce?

While air source heat pumps offer significant energy and environmental benefits, noise can still matter.

Depending on the model, operating conditions and installation, an air source heat pump can produce noise levels of up to around 60 dB(A). The actual noise experienced by nearby occupants will depend on factors such as the distance from the unit, surrounding buildings, background noise and how the equipment has been installed.

Where noise from equipment could affect neighbouring properties, an assessment may be required to determine whether the predicted or measured noise is likely to cause a disturbance.

For industrial or commercial noise sources affecting residential areas, noise is commonly assessed using British Standard BS 4142. The standard considers the difference between the noise’s rating level and the background sound level.

As a general indication, a difference of around +5 dB may be considered marginally significant, while a difference of around +10 dB can indicate a greater likelihood of adverse response. Site context and noise characteristics are also important when interpreting the results.

Why do air source heat pumps make noise?

An air source heat pump contains several mechanical and electrical components that can generate sound during operation.

The main components include:

• Compressor
• Condenser
• Expansion valve
• Evaporator
• Fan

Although several components contribute to the overall sound output, the compressor and fan are often the most noticeable noise sources.

What does an air source heat pump sound like?

Air source heat pumps can produce a range of sounds during normal operation. These can include:

• A constant low-level hum from the motor and compressor
• Fan noise as air moves through the system
• Vibrations from mechanical components
• Airflow noise through the heat exchanger
• Buzzing from electrical or mechanical components
• Additional sounds during defrost cycles

The character and intensity of the noise can vary depending on the operating conditions. For example, changes in pressure and airflow can affect the sound produced by the heat exchanger and fan.

Frost can also accumulate on the heat exchanger in cold conditions. During defrost cycles, the system may produce different sounds from those heard during normal operation.

For nearby residents, a continuous low-frequency hum can sometimes be more noticeable than a higher-level but intermittent sound. This is one reason assessing the noise characteristics, rather than simply the overall decibel level, matters.

How can air source heat pump noise be reduced?

If you are planning to install an air source heat pump, considering noise at the design stage can help prevent potential problems later.

An acoustic assessment can identify the likely impact of the proposed installation and help determine whether additional noise-control measures are required.

At APT Sound Testing, our air source heat pump acoustic package can include a noise assessment carried out in accordance with the relevant requirements of BS 4142, where applicable.

Where noise levels need to be reduced, acoustic recommendations may include measures such as:

• Optimising the position of the heat pump
• Increasing the separation distance from neighbouring properties
• Using suitable acoustic barriers or enclosures
• Installing absorptive acoustic panels
• Addressing vibration transmission
• Reviewing the specification and operating characteristics of the equipment

The most appropriate solution depends on the individual site, the equipment being installed, and the surrounding environment.

Do you need an air source heat pump noise survey?

If your proposed air source heat pump is located close to neighbouring properties or a noise-sensitive area, an acoustic assessment can help establish whether the installation is likely to meet relevant noise requirements.

A professional noise survey can provide useful information for planning applications, environmental assessments and the design of appropriate noise-control measures.

At APT Sound Testing, we can provide specialist acoustic advice and noise assessments for air source heat pump installations across the UK.

Contact us about an air source heat pump noise survey

If you need advice about sound testing or an air source heat pump noise assessment, get in touch with our team.

For more information, follow our blog or contact us at info@aptsoundtesting.co.uk or call APT Sound Testing directly on 01525 303905.

You can also find out more about our BS 4142 Noise Surveys and download our BS 4142 Noise Survey Checklist.

How can we help?

Why choose APT Sound Testing?

• We strive to get you a pass
• Competitive pricing
• Friendly and proactive service
• Experienced consultants
• UKAS & ISO accredited
• Fast response
• Rapid turnaround of results
• Nationwide coverage
• Single pre-completion solution

If you’re looking for an experienced acoustic consultant or noise engineer, our team can help with noise assessments, acoustic advice and sound testing.

Introducing Plant Noise Surveys

At APT Sound Testing, we understand the growing importance of plant noise surveys, especially when planning authorities require them to ensure compliance with BS4142 standards. If you’ve been asked to conduct a plant noise survey as part of a planning condition, we’re here to help.

Industrial noise is becoming an increasingly critical factor for planning authorities, particularly as the UK government pushes for the redevelopment of brownfield sites. These areas often see industrial and residential developments in close proximity, leading to concerns about noise levels and their impact on local amenity and quality of life. As a result, noise from industrial operations — such as machinery, plant, and equipment — must be carefully assessed and managed to avoid disrupting nearby communities.

Local authorities often impose restrictions on noise emissions, particularly in areas near residential properties, and achieving compliance with sound pressure level limits is essential. These limits can apply either at the site boundary or at sensitive receptors, such as nearby homes. To meet these conditions, it’s crucial to assess current noise levels, set appropriate guidelines, and monitor compliance with noise limits to ensure that noise doesn’t cause harm to local residents.

Our Plant Noise Survey Services

If you’re planning to introduce a new noise source to your site, we will begin by measuring the existing background noise levels over a 24-hour period. This helps us understand the baseline conditions of the area before assessing the potential impact of your new noise source. If the noise source is already present, we’ll measure the noise levels both with and without the source operating to establish the difference.

BS4142 provides the recognised methodology for assessing industrial noise, particularly in areas with residential housing. This standard involves measuring the existing background noise levels, typically using the LA90 measure (the level exceeded for 90% of the time), at different times of day, if necessary. Our consultants are highly experienced in applying the methods and meeting the requirements set out in BS4142, ensuring that your survey complies with the necessary regulations.

Comprehensive Reporting & Mitigation Recommendations

Our team offers detailed survey reports that clearly outline the findings and provide recommendations for noise mitigation measures where necessary. We use noise mapping techniques to demonstrate the practical effectiveness of these measures in real-world conditions. Our assessments can cover a wide range of industrial operations, including air conditioning systems, extraction units, refrigeration equipment, and general industrial plant operations.

We use the latest Norsonic acoustic equipment to conduct our surveys, ensuring accurate and reliable results. Our commitment to using state-of-the-art technology ensures that your noise survey is fully compliant with BS4142 and meets the expectations of your local authority.

If your local authority has requested that you undertake a BS4142 noise assessment, don’t hesitate to get in touch. We can guide you through the process, providing expert advice and delivering a professional noise survey that helps you achieve compliance. Contact us today at 01525 303905 or email us at info@aptsoundtesting.co.uk for more information.

Let APT Sound Testing help you manage industrial noise and navigate the planning process with ease.