Permitted Development (England) and noise assessment (UK)

There has been an easing of Permitted Development rules in England, and changes to the MCS 020 noise assessment for the whole of the UK.
By Justin at Checkmark |
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Today, 29 May 2025, amendments to The Town and County Planning (General Permitted Development) (England) (Amendment) Order 2025 Opens in a new window have become part of planning law. To support these changes, there is a new, more complex, version of the Microgeneration Certification Scheme’s MCS 020 noise assessment.

Planning in England

The Permitted Development (PD) amendments seem to be generally welcomed by the media, including the BBC Opens in a new window. The changes to Class G Opens in a new window, which affects heat pumps and air conditioners which can provide heating, include:

  • Dropping the restriction preventing installation within one metre of a boundary
  • Allowing for two heat pump units instead of one
  • Increasing the size limit of external units from 0.6m3 to 1.5m3

Noise

To address potential increases in noise resulting from the easing of PD, an update to MCS 020 has been issued by mcscertified.com  Opens in a new window (see Installer Standards > General Scheme Requirements), along with a new calculation spreadsheet. The calculation is now much more complex. Checkmark will be studying this, and updating its information pages in the coming days.

It should be noted that, prior to this change, the English planning legislation specified the required noise assessment as ‘MCS 020 or equivalent’. The ‘or equivalent’ alternative has now been dropped. This small change has had a significant impact, because it means that the noise assessment forms offered by people such as Heat Geek Opens in a new window (as part of their YouTube guide Opens in a new window) are no longer acceptable.

The good news for DIY installers is that the new MCS 020 a) Issue 1.1 Opens in a new window is free for personal use. However, commercial use is restricted to those organisations with MCS certification, which many small operators find expensive Opens in a new window. It should be remembered, of course, that it is ultimately the customer who ends up paying for these accreditations!

Final thoughts

While Checkmark welcomes relaxation of PD to encourage uptake, it is concerned that parts of the legislation rely on standards controlled and published by a separate organisation (The MCS Charitable Foundation). It is even more concerning that the organisation’s wholly owned subsidiary stands to gain significantly from installer certification and related charges.

The removal of ’equivalent standards’ from PD may have been well intentioned, but has resulted in a situation where installers are not legally required to be MCS certified, but now can’t do a noise assessment unless they are.

A previous blog post, written prior to these PD changes, outlines some of Checkmark’s concerns regarding MCS. Removing ’equivalent standards’ from PD means that those concerns have now increased.