Over the past few years, heat pumps have evolved from niche renewable energy technology to appearing centre stage in the UK’s strategy to decarbonise heating in both homes and commercial buildings.
According to data from the Microgeneration Certification Scheme (MSC), certified heat pump installations rose by around 19% in 2023 compared with 2022, and sales of hydronic heat pumps were up 63% in 2024. Support through the Boiler Upgrade Scheme, now offering grants of up to £7,500, is helping accelerate adoption.
The government’s ambition is bold – 600,000 installations annually by 2028 – but as uptake rises, planning rules are emerging as a key stumbling block.
Why are heat pumps so popular?
Heat pumps extract heat from the air, ground, or water to warm buildings. The most common are:
- Air-source heat pumps: outdoor units drawing heat from the air.
- Ground-source heat pumps: loops or boreholes drawing heat from the ground.
- Water-source heat pumps: using lakes, rivers, or groundwater.
There are also more specialised / hybrid systems available that integrate with solar thermal and PV panels, or existing gas boilers.
The pros: lower carbon emissions, higher efficiency than boilers, and long-term savings as the grid decarbonises, plus low maintenance after installation.
The cons: high upfront costs, space requirements and additional upgrades may be necessary such as radiators and better insulation.
Planning permission – the battleground
As heat pumps proliferate, a key set of challenges has also appeared around planning permission.
Most domestic heat pumps in England can be fitted under permitted development rights (PDRs), meaning, in theory, that no planning application is needed if certain rules are met. These rules include:
- The outdoor unit must meet MCS 020 standards for noise.
- Size limits apply. Up to 1.5 m³ for houses and 0.6 m³ for flats.
- Detached houses can have up to two units under PDR; others are usually limited to one.
- Units aren’t permitted on pitched roofs, and on flat roofs they must be at least one metre from the edge.
- PDR does not apply to listed buildings, Scheduled Monuments, or where Article 4 restrictions are in place.
- In conservation areas, PDR is only allowed if the unit isn’t on a highway-facing elevation or visible from a road.
However, despite some relaxation of requirements in May 2025, the rules are still complex and there are many cases where planning permission is required.
According to Nu-Heat, when permission is needed, the main hurdles are noise, appearance (particularly with regards to visibility from public spaces) and heritage considerations. For prime residential areas (large, detached homes, conservation areas, heritage or listed properties) the planning constraints are tighter. Local authorities may even revoke or limit permitted development rights via Article 4 of the Town and Country Planning Order 2015, meaning that even if a proposal would seem to comply with permitted development, permission is still required locally.
How to keep it simple
- Check the Planning Portal and your local authority’s rules before installation.
- Use an MCS-certified installer, who will ensure compliance with technical, noise and build standards.
- Noise assessment: Even under PDR, do a proper assessment of noise from the external unit (consider siting, distance to neighbours’ habitable rooms, screening, background noise). It can save time or avoid refusal.
- Choose discreet locations (side or rear elevations, screened where possible).
- Get expert help: surveyors, architects, and/or planning consultants can smooth the process, particularly in conservation or listed settings.
