Heat pump and wind turbine sound calculations for permitted development installations

[edit] Introductory BSRIA Step-By Step guide

Permitted development heat pump installations now use the updated air source heat pump (ASHP) sound calculation standards document from MCS - MCS 020 a).

The standard provides a comprehensive and easy-to-understand calculation methodology for installers, enabling them to easily determine if their heat pump installation is compliant with specified noise limits.

Below is a quick, graphical guide from BSRIA explaining the standard and the calculation for permitted development installations.

For more information visit BSRIA Acoustic testing, Acoustics Testing at BSRIA and https://www.bsria.com/uk/

[edit] MCS 020 background

The first version of MCS 020 Planning Standards for Permitted Development Installations of Wind Turbines and Air Source Heat Pumps" (ASHPs) was issued as early as 2011, outlining noise and environmental impact assessment procedures for air source heat pumps and small wind turbines to ensure they complied with permitted development requirements.

In March 2012, following a consultation, the Conservative government published the summary of responses and the government response. The proposals covered domestic and non-domestic installations such as building-mounted and standalone wind turbines, air, ground, and water source heat pumps and solar panels, as well as biomass flues, combined heat and power (CHP) and charge points.

The Guidance When is permission required? was first published in March 2014, and the Town and Country Planning (General Permitted Development) (England) Order 2015 Class G – installation or alteration, etc., of air source heat pumps on domestic premises – was amended in April 2015. In June 2015 the government published Guidance on Renewable and Low Carbon Energy to help local councils develop suitable policies.

In 2019 MCS 020 was updated, with many contractors and consumers having raised concerns that existing PDRs remain a barrier to installation, despite improvements in heat pump technology as well as wind and solar technology. For example, minimum distances from boundaries, particularly for terraced homes, are seen as barriers to uptake. Many relevant government documents were consulted upon and updated at various intervals up to 2024, aiming to ease the rules around renewables and to revise MCS 020, simplifying the process and encouraging wider installation of heat pumps.

In February 2024 the Conservative government consulted on "Changes to various permitted development rights". In March of the same year the Research Briefing Planning in England: Permitted development and change of use was published. A wide focus document, it also mentions microgeneration saying, "Government guidance also states that LPAs need 'a particularly strong justification' to withdraw PDRs for a wide area, PDRs which are subject to prior approval, PDRs for agriculture and forestry development, and PDRs for microgeneration equipment (for example, solar panels)."

[edit] MCS publishes updated split versions of MCS 020

In March 2025 rather than the single document, MCS issued two MCS Standard Documents :

• MCS 020 a) ISSUE 1.0 Air Source Heat Pump Sound Calculation (For Permitted Development Installations)
• MCS 020 b) ISSUE 1.0 Wind Turbine Sound Calculation (For Permitted Development Installations)

ASHPs are classified as within permitted development, meaning they can be installed without planning permission if certain conditions are met. These conditions vary across the UK but all require compliance with MCS 020, which assesses installation noise levels. The update of MCS 020 was driven by the consultations, and the subsequent announcement on amendments to existing PDRs that apply in England to improve clarity for installers such as:

• Remove the 1m boundary rule, enabling heat pumps to be installed within 1m of the property boundary.
• Increase the size limit of the heat pump for dwelling houses from 0.6m3 to 1.5m3.
• Double the number of heat pumps permitted, from one to two for detached dwelling houses.
• Support the rollout of air-to-air heat pumps that can also provide a cooling function.

[edit] Key changes in MCS 020 a)

The key changes are as follows:

MCS will hold the A-weighted sound power level for MCS certified products on the MCS Product Directory. This figure is to be determined by manufacturers at the same conditions as the Eco Design Directive and MCS will issue guidance to clarify what those conditions are.

MCS has clarified:

• What can and cannot be considered a solid barrier.
• How to determine the assessment position.
• What can and cannot be considered a reflective surface.
• The definition of a habitable room.

MCS will introduce a methodology for including up to two air source heat pumps in the MCS 020 (a) sound calculation.

MCS will provide installers with options for completing the sound calculation which will include the current paper-based method and an Excel tool.

MCS will include in the Excel tool the capability of completing the sound calculation for up to four air source heat pumps to benefit those installing under full Planning Permission.

Working with DESNZ and other industry stakeholders, MCS will develop a guidance document for installers on installation noise mitigation measures for air source heat pumps.

Compliance with MCS 020 a) under PDR will apply irrespective of whether it’s an MCS certified installation or not.

Compliance with this update is mandatory for installers seeking to install air source heat pumps under Permitted Development from the date of implementation – 20 September 2025.

[edit] MCS Database

The MCS Installations Database (MCS MID), is a central online database that holds the information of every MCS certified small scale, low carbon installation in the UK since 2010. It is the most comprehensive reference for small scale, renewable energy installations in the UK. It is unique to MCS. Access is granted by Certification bodies.

If an MCS Installer has been suspended or removed from the Scheme, access to the MID is revoked, unable to then view, generate or make amendments to MCS certificates. Customers facing issues with this should contact the Helpdesk Team. Reinstated installers regain access the Scheme via the Certification Body.

For further information or access to MCS Standards and Scheme documents visit: https://mcscertified.com/

[edit] Related articles on Designing Buildings

• Air source heat pumps.
• Biomass.
• BSRIA domestic hot water heat pumps testing.
• Domestic building services compliance guide.
• Feed-In tariff.
• Ground source heat pump.
• Making the most of renewable energy systems DG 531.
• Microgeneration certification scheme
• Micro CHP.
• Micro grid.
• Microgeneration.
• Noise v sound.
• Non-domestic building services compliance guide.
• Pre-completion sound testing.
• Renewable energy.
• Renewable Heat Incentive.
• Renewable Energy Consumer Code RECC.
• Solar photovoltaics.
• Solar thermal.
• Sound.
• Sound absorption.
• Sound absorption coefficient.
• Sound frequency.
• UKAS accreditation for sound absorption testing.
• Wind turbine.

[edit] External links

https://mcscertified.com/mcs-has-published-an-updated-version-of-mcs-020/

https://www.gov.uk/government/publications/microgeneration-certification-scheme-mcs-transfer-to-mcs-service-company