Since 28 May 2026, MCS 020 a) is the only certification scheme accepted for air source heat pump installations under England’s permitted development rules. The old “equivalent” route, which let installers use manufacturer noise data or a third-party acoustic assessment, closed that day, and the noise limit tightened from 42 dB(A) to 37.0 dB(A). Every permitted-development heat pump install in England now needs a signed MCS 020 a) sound calculation on file before work starts.
For most homeowners this is a cleanup of the rules, not a barrier to a new install. The “equivalent” route was rarely used; large MCS-certified installers already worked to the MCS planning standards by default, because that is the path that gets the BUS grant paid. With the UK now past 250,000 certified heat pump installations, the volume of installers running compliant surveys is already high. The impact lands on installs that relied on non-MCS acoustic methods, and on tight plots where the unit sits close to a neighbour.
What does MCS stand for?
MCS stands for the Microgeneration Certification Scheme, the UK quality mark for small-scale renewable energy since 2007. It certifies both products and installers across heat pumps, solar panels, battery storage, biomass and small wind turbines.
“MCS certified” on a quote means three things: the installer is registered with the scheme, the equipment is MCS-listed, and the finished install is signed off against MCS technical standards and logged on the national database. UKEM’s heat pump, solar and battery installations are all MCS certified; our registration is listed on the MCS installer register.
The scheme publishes its standards as numbered documents, and MCS 020 is one of them: the planning standard for noise. That is why the same acronym turns up on a solar quote and in a heat pump planning conversation, and the two uses are easy to conflate.
What does MCS 020 cover?
MCS 020 started life as the “MCS Planning Standards for Permitted Development Installations of Wind Turbines and Air Source Heat Pumps on Domestic Premises”, a single document covering both technologies. It has since been split in two: MCS 020 a) for air source heat pumps and MCS 020 b) for small wind turbines.
For heat pumps, MCS 020 a) is a sound calculation. The installer takes the manufacturer’s sound power figure, applies distance, reflection and barrier corrections, and produces a predicted sound pressure level at each assessment position: 1m from the centre of every door and window of a neighbour’s habitable rooms. The ceiling in England is 37.0 dB(A). At or below at every position, the install qualifies for permitted development. Above it at any position, it needs a full planning application.
Passing the calculation on its own does not grant permitted development; the wider rules still set conditions on unit size and position. The MCS standards library holds the current documents and the official calculator.
What changed on 28 May 2026?
Until 28 May, England’s permitted development rules accepted either the MCS planning standards or an “equivalent” approach: manufacturer-published noise data or a bespoke acoustic assessment from a qualified engineer. From 28 May, only MCS 020 a) counts, and the test itself became stricter. The Planning Portal’s MCS guidance is the primary published reference.
| Rule | Before 28 May 2026 | From 28 May 2026 |
|---|---|---|
| Accepted certification | MCS 020 or “equivalent” route | MCS 020 a) only |
| Acoustic ceiling | 42 dB(A) | 37.0 dB(A) |
| Assessment positions | 1m from the nearest neighbour’s habitable window | 1m from every neighbouring door and window of habitable rooms |
| Who the noise rule binds | Installers using MCS 020 or an equivalent method | Every installer in England, MCS certified or not |
| Fail outcome | Full planning application | Full planning application |
Two things changed at once: which document proves compliance, and how strict the test is. The ceiling dropped by 5 dB(A), and the calculation now has to clear every affected window and door, not just the nearest one. Scotland and Wales continue to use the original MCS 020 with its 42 dB(A) limit.
How does the MCS 020 noise assessment work?
The assessment is a desk calculation the installer runs at survey stage, before any equipment is ordered. The steps are fixed by the standard:
- 1 Start with sound power The A-weighted sound power level comes from the manufacturer's datasheet or the MCS product directory; quiet-mode figures are not allowed.
- 2 Count reflective surfaces The ground and any walls within 1m of the unit reflect sound outward, raising the directivity factor in the formula.
- 3 Measure the distance Straight-line distance from the centre of the unit to each assessment position, to the nearest 0.1m.
- 4 Apply barrier corrections A solid wall or thick fence blocking the view of the window subtracts up to 10 dB(A). Open fences, gappy panels and hedges count for nothing.
- 5 Compare against 37.0 dB(A) Every assessment position must come out at or below the limit. If any position fails, the unit moves, a quieter model goes in, or the install goes to full planning.
MCS publishes the calculation as a paper form and an official Excel calculator, both free in the standards library. The Excel tool handles up to two heat pumps for permitted development and up to four under full planning. As a homeowner you never fill this in yourself, but you are entitled to see the completed calculation, and a good installer will share it before ordering equipment.
What does 37 dB(A) mean in real terms?
37 dB(A) is quiet. A domestic fridge at 1m sits at around 40 to 45 dB(A); a library reading room is around 35 to 40 dB(A); suburban daytime background is typically 45 to 55 dB(A). The ceiling is set well below daytime background, which is why heat pumps in normal UK gardens rarely cause a complaint once installed correctly.
Fail cases tend to involve tight terraced gardens, semi-detached side returns close to a neighbour’s living room, or a unit within 2 to 3m of a habitable room window. A quieter R290 model from Samsung, Vaillant, or Ideal (sound power around 56 to 58 dB at full load) clears the ceiling on most UK plots; if not, the install needs planning or a different location. Our heat pump noise guide compares those figures with everyday sounds.
Does MCS 020 apply to solar panels?
No. MCS 020 is a noise standard, and a solar install has nothing for it to measure: panels are silent, and a modern inverter hums at a level you would struggle to hear from the next room. There is no acoustic planning test for solar.
The reason solar owners keep meeting the acronym is that MCS certifies solar too, and at much larger volume. The UK is past 2 million certified solar installations against around 250,000 heat pumps, so most people first see the MCS logo on a solar quote. Solar has its own MCS installation standards, and the certificate issued at handover is what makes a system eligible for Smart Export Guarantee payments; every UKEM solar install is registered with MCS at handover for exactly that reason.
So if you arrived here searching for MCS in a solar context: the scheme covers your panels, but the 020 standard does not. The number that matters for solar is on your MCS certificate, not in a planning calculator.
The wider MCS Redeveloped Installer Scheme
Separate from the 28 May planning change, MCS is rolling out a broader overhaul through 2025 and 2026. The MCS Redeveloped Installer Scheme shifts the focus from quality-management-system paperwork to delivered quality on site: how the unit performs, whether it was commissioned correctly, and whether the homeowner has working cover years later.
The headline new requirement is a 6-year workmanship warranty. Certified installers must back every install with an Insurance-Backed Warranty (IWA) or an equivalent product that pays out on labour defects for six years after handover. That sits on top of the manufacturer’s product warranty (typically 5 to 10 years) and the standard installer guarantee. Labour has historically had the thinner cover, so this is a useful tightening.
What should homeowners ask their installer?
Three questions cover most of it. Is the installer MCS-certified, and can they share their MCS number (checkable on the MCS certified installer directory)? Will they share the completed MCS 020 a) calculation before any equipment is ordered? And what 6-year workmanship cover sits in the handover pack alongside the manufacturer warranty and the commissioning report?
For most installs, none of this is new work; it has simply shifted from “good practice” to “required”. See our heat pump running costs guide and our comparison of heat pumps versus gas boilers, or head to the heat pumps product page or the grants hub when you are ready to price up an install. The Boiler Upgrade Scheme claim is filed by the installer on your behalf.
Frequently asked questions
What does MCS stand for?
MCS stands for the Microgeneration Certification Scheme, the UK quality mark for small-scale renewable energy since 2007. It certifies products and installers across heat pumps, solar panels, battery storage, biomass and small wind turbines. 'MCS certified' on a quote means the installer is registered with the scheme, the equipment is MCS-listed, and the completed install is signed off against MCS technical standards and registered on the national database. The scheme also publishes numbered standards; MCS 020 is the planning standard covering noise.
Do I need planning permission for a heat pump in England?
In most cases, no. An air source heat pump installed under permitted development avoids a planning application, provided the install passes MCS 020 a). Since 28 May 2026 that is the only certification route accepted; the older 'equivalent' option (using manufacturer data or another acoustic method) has closed. If the predicted noise level stays at or below 37 dB(A) at 1m from every door and window of your neighbours' habitable rooms, the install stays under permitted development.
What is MCS 020 in plain terms?
MCS 020 is the MCS planning standard for noise. It began as one document covering air source heat pumps and wind turbines, and has been split in two: MCS 020 a) for heat pumps and MCS 020 b) for small wind turbines. For heat pumps, it sets out how the installer must calculate the predicted noise level at each neighbour's habitable-room windows and doors, what allowances apply for barriers such as walls and fences, and the 37 dB(A) ceiling that applies in England. The installer completes the calculation before the install and keeps it on file. That paperwork is what proves your heat pump qualifies as permitted development.
Does MCS 020 apply to solar panels?
No. MCS 020 is a noise standard, and a solar install has nothing for it to measure; there is no acoustic planning test for solar panels. Solar comes up alongside MCS because the scheme certifies solar too: panels, batteries and installers all carry MCS certification under their own standards. That certificate matters for a different reason, as it is what makes a solar install eligible for Smart Export Guarantee payments. See our Smart Export Guarantee guide for how export payments work.
What happens if my install fails MCS 020?
You need a full planning application. In practice, most installers will re-site the unit or specify a quieter model to keep the predicted level at or below 37 dB(A) at every assessment position, because going through full planning adds 8 to 13 weeks and a fee. Models from Samsung, Vaillant, and Ideal publish sound power figures low enough to pass on most UK plots. The fail cases tend to be tight terraced gardens, very close boundary walls, or a unit pushed up against a neighbour's bedroom window.
Does this change my Boiler Upgrade Scheme grant?
No. The Boiler Upgrade Scheme has required an MCS-certified installer and MCS-listed equipment since launch. The 28 May change tightened the planning route, not the grant route. The published rates (£7,500, or £9,000 until 31 March 2027 for oil and LPG homes) still pay out the same way for eligible installs. See our 2026 UK energy grants guide for the full eligibility list.
What is the MCS Redeveloped Installer Scheme?
It is the broader overhaul MCS is rolling out across 2025 and 2026, separate from the MCS 020 a) planning change. The headline shift is from quality-management-system paperwork to delivered quality on site, plus a new 6-year workmanship warranty requirement. Certified installers must back the install with an Insurance-Backed Warranty (IWA) or an equivalent product. For homeowners, that means longer cover on the labour side of the install, on top of the manufacturer's product warranty.
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