Noise and neighbours
Legislation has changed
On 29 May 2025, new rules on planning came into effect in England. In addition, a new version of MCS 020, called MCS 020 a), was released and has been mandatory since 20 September 2025.England, Northern Ireland, Scotland and Wales all refer to the MCS Planning Standards or equivalent. MCS 020 a) is primarily about noise and neighbours. It is a calculation designed to determine whether noise levels of an outdoor unit would impact on neighbours.
New planning rules, introduced in May 2025, relaxed the requirements related to Permitted Development Rights in England, including:
-
removal of the 1m boundary rule, enabling heat pumps to be installed within 1m of a property’s boundary.
-
Increasing the number of heat-pumps permitted from one to two (for detached dwelling houses).
-
Increasing the unit size limit from 0.6m3 to 1.5m3 (not for blocks of flats).
-
Supporting air-to-air heat pumps that also have a cooling function.
How to do MCS 020 noise calculations
Following the increase in the number of permitted units in England from one to two, along with other changes, MCS realeased a new version of the MCS 020 Noise Assessment calculation tool - MCS 020 a). The new calculation tools is available on the MCS website 
.
Whilst the new calculation is more complex than the previous version, certain issues have been clarified, including what is considered a solid barrier, and how the assessment position is determined. MCS 2020 a) forms part of the MCS Standards Tools library .
An important point to note is that the MCS 020 a) Standard is freely available for personal use, but commercial use by those not holding a valid licence to use the MCS mark is prohibited. This effectively means that any commercial installer must by MCS licensed, but there is nothing stopping you as an individual from doing the noise calculations yourself. Checkmark recommends you keep your documentation as evidence the assessment was successfully completed.