Are Heat Pumps Noisy? UK Noise Rules Explained (2026)

Are heat pumps noisy? It is one of the most common questions UK homeowners ask before switching, and the short answer is no, not really. A modern heat pump makes about as much sound as a fridge hum or a gas boiler, and a government review found only a low number of noise complaints.

But the rules about heat pump noise changed in 2026, and much of what you will read online is now out of date. The old 42 dB limit you see quoted everywhere has been replaced, and England now uses a stricter 37 dB standard with a mandatory noise calculation for every installation. This guide gives you the real decibel figures with sources, explains what makes a heat pump louder or quieter, and covers what the rules mean for you and your neighbours.

Are heat pumps noisy?

No, not in the way most people fear. A heat pump makes a low, steady hum from its fan and compressor, and in normal use it is easy to miss from inside your home or from next door.

The evidence backs this up. Research commissioned by the innovation charity Nesta and carried out by acoustic consultants Apex Acoustics found that multiple air source heat pumps running on the same street would not noticeably increase background noise, even in the densest terraced housing with every unit at full power. Katy King, Nesta’s deputy director for sustainable future, said a properly installed unit is “only as audible as the hum of a fridge or the sound of a gas boiler” (Source: elemental).

A government review of heat pump noise also found a “low number of complaints” from the public (Source: Homebuilding & Renovating).

So why do people think heat pumps are loud? The belief can be traced back to the early models sold in the UK, which were noisier than today’s units. “At the time, they were quite noisy, but that’s not the case today,” as one industry expert put it (Source: Homebuilding & Renovating).

How loud is a heat pump in real numbers?

Here are the figures that matter, all from named sources:

• Most air source heat pumps produce 40 to 60 decibels measured at one metre, according to manufacturer Environ Technologies (Source: Homebuilding & Renovating).
• Steve Cole, retrofit co-ordinator at the Centre for Sustainable Energy, says modern heat pumps “typically produce 40 to 60 decibels of sound, equivalent to a quiet office” (Source: Homebuilding & Renovating).
• Stand right next to a running unit and you would expect noise “similar to a microwave or a whirring desk-top fan”, says heating specialist Chris Harvey of Stelrad (Source: Homebuilding & Renovating).
• Quieter models go further: Daikin’s Altherma HHT runs at 53 decibels and has earned Quiet Mark certification, the award for quiet technology, thanks to a sound jacket around the compressor, rubber feet and a low-sound fan (Source: Homebuilding & Renovating).
• Mitsubishi Electric’s latest Ecodan model claims to be quieter than the average gas boiler (Source: Homebuilding & Renovating).

To put that in context:

Sound	Typical level
The legal limit at your neighbour’s window (England, 2026)	37 dB
A heat pump at 1 metre	40 to 60 dB
A quiet office	40 to 60 dB

For context, Nesta describes the average heat pump’s hum as about as loud as a refrigerator (Source: elemental).

The key point: the number at the unit is not the number your neighbour hears. Sound drops with distance, and the law measures it at your neighbour’s window or door, not at the heat pump itself.

What are the UK heat pump noise rules in 2026?

In England, an air source heat pump can be installed under permitted development rights, meaning no planning application, but only if it passes the noise test in the MCS 020 a) planning standard.

The current rule, in plain English:

• The noise limit is 37 dB LAeq,5mins.
• It is measured at the assessment position: one metre in front of the centre of a neighbour’s window or door to a habitable room (bedrooms and living rooms count; bathrooms, toilets and kitchens do not), ignoring reflections from that wall (Sources: MCS 020 a) Issue 1.0, MCS Charitable Foundation, 20 March 2025).
• Since 28 May 2026, MCS 020 a) is the only certification route accepted under England’s permitted development rules. The old “equivalent” route, which let installers use manufacturer noise data or a third-party acoustic assessment instead, closed on that date (Source: UKEM Group, October 2026).
• Every permitted development installation now needs a signed MCS 020 a) sound calculation on file before work starts. An installation that does not meet the standard can face enforcement action by the local planning authority (Sources: UKEM Group; MCS 020 a)).

The Chartered Institute of Environmental Health (CIEH) published a professional advice note in 2026 confirming that the fixed 37 dB(A) threshold already builds in a margin for tonal characteristics of heat pump noise. For complex cases, a suitably qualified acoustician can use more detailed modelling (ISO 9613-2) instead of the standard calculation (Source: CIEH, Domestic Air Source Heat Pumps Professional Advice Note (2026)).

What happened to the old 42 dB rule?

The old MCS 020 standard set the permitted development noise limit at 42 dB(A), measured one metre from a neighbour’s window or door. That is the figure most UK websites still quote, but it is outdated.

MCS 020 a) replaced it, tightening the limit from 42 to 37.0 dB(A) (Source: UKEM Group). England’s permitted development rules now point to MCS 020 a) only.

Two things to watch for when reading older guides:

• Any page quoting “42 dB at the boundary” or “42 dB at one metre from the boundary” is describing the old rules.
• The old rule that a heat pump could not be installed within one metre of your property boundary has been removed, the maximum unit size has grown from 0.6 to 1.5 cubic metres, detached homes can now install up to two heat pumps, and air source heat pumps used for cooling (including air to air units) can now benefit from permitted development rights (Source: Cooling Post).

One more catch: Scotland, Wales and Northern Ireland still refer to the older MCS 020 standard for now, so the 37 dB rule described here applies to England (Source: Cooling Post).

What makes a heat pump noisier or quieter?

Not all heat pumps sound the same, and not all installations are equal. These are the factors that actually change how much noise you and your neighbours hear:

How hard it is working. “The greater the workload, the louder the heat pump will be,” says Chris Harvey of Stelrad. That is because of the speed of the fan drawing air into the compressor (Source: Homebuilding & Renovating). In very cold weather the unit works harder, so it can be louder in winter than on a mild day.

The age and design of the model. Early UK models were noticeably louder. Modern designs use sound jackets around the compressor, rubber mounting feet, low-sound fans and front grilles that hide the fan (Source: Homebuilding & Renovating, on the Daikin Altherma HHT).

Where it sits. Hard, reflective surfaces near the unit can bounce sound around. Each reflective surface can add as much as 3 dB, according to installer Rob from Artel31 (Source: Ideal Home). Your installer’s noise calculation accounts for this, which is why siting matters. Avoid pointing the fan outlet straight at a neighbour’s bedroom window, and leave clear space around the unit for airflow.

Extra soundproofing. If you are worried, an acoustic enclosure around the outdoor unit can cut the noise further (Source: Ideal Home).

What should you do about neighbours and planning?

Talk to your neighbours first. If there is any chance you will need planning permission, get your neighbours on side before they receive formal notice from the council. A friendly conversation early on can prevent most disputes (Source: Ideal Home).

Make sure the installer does the noise calculation. In England, your MCS-certified installer must complete the signed MCS 020 a) sound calculation before work starts. Ask to see it. If the numbers pass, the installation can go ahead under permitted development without a planning application (Source: UKEM Group).

If it does not pass, you can still apply for planning permission. The local planning authority will assess the noise on its own terms, often using the BS 4142 method for rating industrial-type sound. The CIEH notes this method can be used to keep adverse impacts as low as reasonably possible (Source: CIEH (2026)).

Know that the rules have teeth. An installation that does not meet MCS 020 a) may face enforcement action from the council, and MCS can sanction installers who skip the standard (Source: MCS 020 a)).

Think about the street, not just your home. Research cited by the CIEH found that cumulative noise from several heat pumps is unlikely to be a problem for detached, semi-detached and terraced houses. It only needs extra care in courtyards or blocks of flats, where units sit close together (Source: CIEH (2026)).

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Frequently asked questions

Will my neighbour hear my heat pump? Probably not, or only faintly. The law caps noise at 37 dB at a point one metre from their window or door, which is a very low level. A properly installed modern unit should not disturb them (Sources: MCS 020 a); elemental).

Are heat pumps louder in winter? They can be. The unit works harder in cold weather to pull heat from the air, and the harder it works, the faster the fan runs and the louder it gets (Source: Homebuilding & Renovating, Chris Harvey, Stelrad).

What if my neighbour complains about the noise? They can complain to the council, which can investigate. If the installation met MCS 020 a) and the permitted development rules, you are on solid ground. If it did not, the council can take enforcement action, so keep your installer’s signed noise calculation as proof of compliance (Sources: MCS 020 a); UKEM Group).

Do I need planning permission because of noise? Not in England if the installation passes the MCS 020 a) noise calculation and meets the other permitted development conditions. If it fails the calculation, you can still apply for planning permission from your local council (Sources: UKEM Group; CIEH (2026)).

Is the 42 dB rule still used anywhere? The old 42 dB limit came from the previous MCS 020 standard. England now uses 37 dB under MCS 020 a). Scotland, Wales and Northern Ireland still refer to the older MCS 020 standard for now (Source: Cooling Post).

Are heat pumps noisy enough to bother neighbours? Are heat pumps noisy? At 40-60 dB they are quieter than most air conditioners. If you are worried that heat pumps are noisy, choose a model under 42 dB and follow the 1-metre boundary guidance.

Sources

• MCS 020 a) Issue 1.0 (20 March 2025), MCS Charitable Foundation
• MCS 020 noise assessment and planning standard, UKEM Group, October 2026
• Domestic Air Source Heat Pumps Professional Advice Note (2026), Chartered Institute of Environmental Health
• Multiple heat pumps on street would not increase background noise, Elemental (Nesta/Apex Acoustics research)
• Government review into heat pump noise, Homebuilding & Renovating
• Are air source heat pumps noisy?, Homebuilding & Renovating
• Heat pump myths debunked, Homebuilding & Renovating
• New planning rules boost heat pump access, Cooling Post
• Do I need planning permission for a heat pump?, Ideal Home

The bottom line

Modern heat pumps are not noisy. They typically produce 40 to 60 decibels at one metre, about the level of a quiet office or a fridge hum, and research shows even a whole street of them would not noticeably raise background noise. The UK rules got stricter in 2026: in England the limit is now 37 dB at your neighbour’s window or door under MCS 020 a), and your installer must complete a signed noise calculation before work starts. If a guide still quotes the old 42 dB rule, it is out of date. Talk to your neighbours, check the installer’s noise calculation, and you should have nothing to worry about.

Last reviewed: 11 October 2026

By TheSolarCost Editorial Team