Glossary
Air source heat pumps and London planning permission
Renewable heating drawing energy from outside air. Increasingly common in new and retrofit projects.
Renewable heating drawing energy from outside air. Increasingly common in new and retrofit projects.
An air source heat pump extracts low-grade heat from outside air and raises it to a useful temperature for radiators, underfloor heating and hot water. A well-designed domestic unit delivers a seasonal coefficient of performance around 3.0 to 3.5, so it produces roughly three units of heat per unit of electricity.
Usually not. An air source heat pump on a house is permitted development under Part 14, Class G, provided it meets the siting and noise conditions and is used solely for heating. The binding one is noise: the installation must meet the MCS planning standard at the nearest neighbouring window.
| Condition | Requirement | Source |
|---|---|---|
| Noise at the nearest habitable room window | 42 dB(A) assessed under MCS 020 | GPDO Part 14, Class G |
| Use | solely for heating the building | GPDO Part 14, Class G |
| Siting | not on a pitched roof, and not above the highest part of the roof | GPDO Part 14, Class G |
| On a wall or roof fronting a highway in a conservation area | not permitted development | GPDO Part 14, Class G |
| On a listed building | listed building consent required | Planning (Listed Buildings) Act 1990 |
| Building regulations | notifiable work; Part L applies to the system | Building Regulations 2010 |
Source: Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 14, Class G, as amended, together with MCS 020 (the Microgeneration Certification Scheme planning standard for noise), read at 1 September 2026. The siting conditions in Class G have been amended more than once in recent years, so confirm the current text against legislation.gov.uk before relying on a specific clearance distance or volume limit.
Usually not. Class G of Part 14 of the GPDO permits one ASHP on a house subject to conditions: the unit must comply with MCS Planning Standards, be sited to minimise its effect on amenity, be removed when no longer needed, and it cannot be installed on a pitched roof or within a listed building's curtilage without consent.
On a flat in a conservation area, or where a wall facing a highway is involved, the permitted right is narrower and an application is often the honest route.
Heat pumps run at 35 to 50 °C flow temperature rather than the 70 to 80 °C a gas boiler uses, so emitters are resized. In a typical London Victorian terrace that means larger radiators in most rooms and a hot water cylinder where a combi boiler previously served instantaneous hot water.
Fabric matters more than the unit. Loft insulation to 270 mm, draught sealing and improved glazing all reduce the heat loss the pump has to meet, which reduces both the capital cost and the running cost.
The installation is notifiable work under Part L and Part G, and the heat loss calculation, emitter schedule and cylinder specification form part of the package. Noise is assessed against the MCS 020 planning standard, which sets a 35 dB(A) limit at the nearest habitable-room window.
How air source heat pump (ashp) plays out in Kingston upon Thames: Royal Borough of Kingston upon Thames (Kingston Council) maintains 22 conservation areas, the Kingston Old Town Conservation Area and the Surbiton Conservation Area among them, and there is no borough-wide Article 4 direction, so permitted development generally survives outside conservation areas. Anyone dealing with air source heat pump (ashp) at a Kingston upon Thames address is therefore working to a £548 householder application decided in 8 weeks, or a £249 prior approval over 6 weeks where air source heat pump (ashp) still qualifies.
| Typical seasonal CoP | 3.0–3.5 |
|---|---|
| Flow temperature | 35–50 °C |
| Permitted development class | GPDO Part 14, Class G |
| Noise limit (MCS 020) | 42 dB(A) at 1 m from neighbouring habitable window |
| Cylinder | Required; typically 180–250 litres |
| Loft insulation target | 270 mm mineral wool |
Yes, provided the heat loss is calculated room by room and emitters are resized. Solid walls raise the heat loss but do not rule it out.
Often yes, particularly where the unit would be visible from a highway.
A compliant installation is limited to 42 dB(A) at a neighbouring habitable-room window under MCS 020.
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