The Warm Homes Plan: Heat Pump Planning Reforms Under Permitted Development, and the Implications for Luxury Properties

From 29^th May 2025, legislation around installing domestic air source heat pumps has been significantly relaxed as part of the UK government’s Warm Homes Plan to accelerate the adoption of low-carbon heating and cooling technology.

Prior to the implementation of this plan, permitted development allowed air source heat pumps only under an onerous set of restrictions. These included proximity to property boundaries, maximum unit size, limited quantity per dwelling, strict noise standards and no allowance for units that provide cooling as well as heating. The legislative amendments have now established a broader set of guidelines for installing air source heat pumps under permitted development.

The Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2025 has addressed many of these, and the full legislation can be found here.

While many of these changes will now make it significantly easier to install air source heat pumps under permitted development, allowances have not been put in place for listed buildings and conservation areas, so planning permission may well still be required – get in touch with our expert team to find out the options for your property.

Key Changes to Heat Pump Permitted Development Legislation in 2025:

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- Previously, air source heat pumps were not allowed to be installed within one metre of the property boundary under permitted development.

      - This rule has now been removed, and units can be positioned directly adjacent to the property lines, which will benefit properties with limited outdoor space.

- Prior to the relaxing of the legislation, air source heat pumps installed under permitted development could not exceed 0.6m3 in size, which is particularly limiting for larger properties.

     - The maximum permitted volume has now been increased to 1.5m3 which will accommodate systems with greater heating and cooling capacity and enable a more sustainable heating option for larger properties.

- Detached properties were previously subject to the generic limit of one air source heat pump per property.

     - This has now been amended to allow 2 heat pumps per detached property, which means that cascade systems can be installed to meet higher heating and cooling demands.

- Air-to-air heat pumps were only allowed under permitted development prior to legislative changes if they were used solely for heating.

      - This has now been amended to allow units that provide cooling as well.

- Previously, MCS (020) regulations around noise from external units allowed heat pumps with sound levels up to 42dB (measured from nearest window of closest neighbour)

      - This has been tightened to 37dB as part of the amendments to MCS (020)a. With this in mind it’s critical to engage a specialist designer who can cover all necessary acoustic reports to ensure system compliance.

As part of the Warm Homes Plan, the government provides a grant towards upgrading from unsustainable heating system such as gas boilers towards installing a more sustainable alternative, for example heat pumps; however, this only applies to air-to-water heat pumps at this time, so the Boiler Upgrade Scheme cannot be applied to air conditioning units.

The 2025 reforms to permitted development rights mark a significant step toward modernizing England's residential climate control infrastructure. For prime property owners, these changes offer new opportunities to enhance comfort and energy efficiency as UK summers become longer and hotter. However, it's important to navigate these developments with a clear understanding of the technical, aesthetic, and regulatory considerations involved.

As always, consulting with qualified professionals and staying informed about the latest regulations will ensure that any upgrades align with both personal preferences and legal requirements - get in touch with our experienced team to discover your options.