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Class M: Water source heat pumps on non-domestic premises
Class M allows a water source heat pump within the curtilage of a non-domestic building, subject to the area of the installation and its associated pipes.
The total surface area occupied, including pipes, must not exceed 0.5 hectares.
Need help with permitted development?
Permitted development can avoid a full planning application, but only if the right applies and every relevant limit and condition is met. Planning Geek can check the planning history, Article 4 directions and other restrictions, and help with a lawful development certificate or prior approval where needed.
Other checks
Check that the site is within the building’s curtilage and is not domestic premises. Listed building consent may still be needed where works affect a listed building’s special interest; water and environmental consents are separate from planning permission.
The domestic equivalent is Class D. Read Part 14, Class M.
Legislation
Class M – installation or alteration etc of water source heat pump on non-domestic premises
Permitted development
M. The installation, alteration or replacement of a microgeneration water source heat pump within the curtilage of a building other than a dwellinghouse or a block of flats.
Conditions
M.1 Development is permitted by Class M subject to the condition that the total surface area covered by the water source heat pump (including any pipes) must not exceed 0.5 hectares.
Explore GPDO Part 14
- Part 14 overview: Renewable energy
- Class A: Solar on domestic buildings
- Class B: Stand-alone domestic solar
- Class C: Domestic ground source heat pumps
- Class D: Domestic water source heat pumps
- Class E: Domestic biomass flues
- Class F: Domestic combined heat and power flues
- Class G: Domestic air source heat pumps
- Class H: Wind turbines on domestic premises
- Class I: Stand-alone domestic wind turbines
- Class J: Solar on non-domestic buildings
- Class K: Stand-alone non-domestic solar
- Class L: Non-domestic ground source heat pumps
- Class M: Non-domestic water source heat pumps
- Class N: Non-domestic biomass flues
- Class O: Non-domestic combined heat and power flues
- Class OA: Solar canopies in commercial car parks
- Paragraph P: Definitions used in Part 14
- GPDO index
- Previous: Part 13: Water and sewerage
- Next: Part 15: Power related development
Page updated: 24th September 2026