Amendments to Class G of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 took effect on 29 May 2025, made by the Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2025 (S.I. 2025/560)1. Class G sets out the permitted development rights for installing, altering or replacing a microgeneration air source heat pump on a dwellinghouse or block of flats, or within their curtilage1.
The order omitted words in paragraph G.1, substituted words in paragraphs G.2(a) and G.2(d), omitted paragraph G.2(e), omitted paragraph G.3(a) and inserted paragraph G.3(aa)1. Paragraph G.1 previously required that the pump comply with the MCS Planning Standards; the words omitted from it are not identified in the text as published1. Paragraph G.2(a) now sets the number of pumps permitted: more than one air source heat pump is not permitted on, or within the curtilage of, a dwellinghouse which is not detached, or a block of flats, and more than two are not permitted on, or within the curtilage of, a detached dwellinghouse1.
Paragraph G.2(d) now sets the volume limit for the outdoor compressor unit including any housing: 1.5 cubic metres for a dwellinghouse and 0.6 cubic metres for a block of flats1. Paragraph G.2(e) has been omitted; its former content is not reproduced in the published text1. Paragraph G.3(a) has been omitted and paragraph G.3(aa) inserted in its place, so that development is permitted subject to the condition that the air source heat pump is not solely used for the purpose of cooling1.
The remaining conditions are unchanged: the pump must, so far as practicable, be sited to minimise its effect on the external appearance of the building and on the amenity of the area, and must be removed as soon as reasonably practicable when no longer needed1. Other restrictions in Class G are also unchanged, including that development is not permitted if the pump would be installed on a pitched roof, on a flat roof within 1 metre of the external edge, on a scheduled monument, or on a building or land within the curtilage of a listed building1. In a conservation area or World Heritage Site, installation on a wall or roof fronting a highway, or nearer to a highway than the nearest part of the building, is not permitted1.
"Development is permitted by Class G subject to the following conditions"
| Provision | Change from 29 May 2025 |
|---|---|
| G.1 | Words omitted1 |
| G.2(a) | Words substituted: one pump for non-detached dwellings and blocks of flats, two for detached dwellinghouses1 |
| G.2(d) | Words substituted: 1.5 cubic metres (dwellinghouse), 0.6 cubic metres (block of flats)1 |
| G.2(e) | Omitted1 |
| G.3(a) | Omitted1 |
| G.3(aa) | Inserted: pump not solely used for cooling1 |
Why it matters for households
Class G is the route by which a domestic air source heat pump can be installed without a planning application, so the limits it sets determine how much heating and cooling capacity a property can add under permitted development. The substituted paragraph G.2(a) fixes the number of units by property type, and the substituted paragraph G.2(d) fixes the size of the outdoor compressor unit, which is the part of the installation most likely to be visible from outside. The inserted condition in paragraph G.3(aa) ties the permitted development to the pump not being used solely for cooling, which affects how a unit installed under Class G can be operated. Where a property is covered by an Article 4 direction, permitted development rights may be withdrawn, and the Class G limits would not apply in the same way.
What happens next
The amendments took effect on 29 May 20251. No further steps are set out in the text of the order as published.
Sources4 cited
- [](https://www.legislation.gov.uk/uksi/2015/596/schedule/2/part/14/crossheading/class-g-installation-or-alteration-etc-of-air-source-heat-pumps-on-domestic-premises/data.xml), legislation.gov.uk
- [](https://www.legislation.gov.uk/uksi/2015/596/schedule/2/part/14/crossheading/class-g-installation-or-alteration-etc-of-air-source-heat-pumps-on-domestic-premises/data.xht), legislation.gov.uk
- The Town and Country Planning (General Permitted Development) (England) Order 2015, legislation.gov.uk
- The Town and Country Planning (General Permitted Development) (England) Order 2015, legislation.gov.uk