equipment, size of the unit and surrounding planning restrictions still need to be checked.

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This guide relates primarily to homes in England.

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Air source heat pump planning permission

 

An air source heat pump normally includes an external unit which extracts heat from the outside air and transfers it into the home.

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Because this equipment is visible externally and produces some operational sound, its position has traditionally been an important planning consideration.

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Current permitted development rights can apply to the installation, alteration or replacement of an air source heat pump:

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• on a house

• on a qualifying block of flats

• within the garden or grounds of a house

• within the grounds of a qualifying block of flats

• on another building within the residential curtilage.

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A block of flats must consist wholly of flats for these particular permitted development rights to apply.

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Air source heat pump permitted development

 

To qualify as air source heat pump permitted development, the installation must comply with all of the relevant planning conditions.

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One of the most important requirements is compliance with the appropriate Microgeneration Certification Scheme planning standard.

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From 28 May 2026, MCS 020a is the permitted certification standard referenced by Planning Portal guidance for domestic permitted development installations.

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The standard includes assessment of noise from the proposed heat pump installation.

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This means that even though the former one-metre boundary rule has been removed, the effect on neighbouring properties still matters.

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Can a heat pump be installed within one metre of a boundary?

 

Yes, potentially.

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Before the May 2025 changes, permitted development rules generally required an air source heat pump to be positioned at least one metre from a property boundary.

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That restriction was removed.

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A qualifying heat pump can now potentially be installed within one metre of the boundary, provided the installation satisfies the other permitted development requirements, including the relevant MCS noise assessment.

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This is particularly useful for terraced and semi-detached properties where outside space may be limited.

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However, just because equipment can legally be positioned closer to a boundary does not necessarily mean that every location is sensible.

The relationship with neighbouring windows, bedrooms, patios and gardens should still be considered when choosing the best position.

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How large can an air source heat pump be?

 

The permitted development rules place limits on the volume of the external compressor unit.

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For a house, the outdoor compressor unit, including its housing, must not exceed 1.5 cubic metres.

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For a qualifying block of flats, the maximum volume is 0.6 cubic metres.

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The 1.5m³ allowance for houses represents a significant increase from the previous 0.6m³ limit and allows a wider range of modern heat pumps to potentially qualify as permitted development.

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How many heat pumps can you install?

 

The number of heat pumps permitted depends upon the type of property.

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For a detached house, the first two air source heat pumps can potentially qualify as permitted development.

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For a house which is not detached, or for a qualifying block of flats, generally only the first air source heat pump installation benefits from these permitted development rights.

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If additional units are required, a planning application may be necessary.

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This can be relevant for larger houses where two heat pumps are used together as a cascade system.

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Can a heat pump be installed on the roof?

 

The type of roof matters.

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An air source heat pump installed on a pitched roof does not qualify as permitted development under the domestic Class G rules.

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Installation on a flat roof can potentially qualify, but every part of the heat pump must be at least one metre from the external edge of the roof.

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Roof positioning may therefore be possible for some properties, but a ground-level position is often considerably easier to accommodate.

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Heat pump positioning and appearance

 

Even where all of the dimensional requirements are satisfied, permitted development conditions require an air source heat pump to be positioned, so far as practicable, to minimise its effect on:

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• the external appearance of the building

• the amenity of the surrounding area.

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Choosing the right position is therefore important.

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A heat pump discreetly positioned at the rear or side of a property may have considerably less visual impact than the same equipment installed prominently on the front elevation.

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The shortest pipe route is not always the best planning solution.

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Heat pump noise and planning permission

 

Noise is one of the main reasons people worry about heat pump planning permission.

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Modern air source heat pumps are generally designed to operate relatively quietly, but their effect depends on the unit, installation and position in relation to neighbouring properties.

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Permitted development installations must comply with the relevant MCS planning standard and sound calculation. The government has retained this noise control even after removing the former one-metre boundary restriction.

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This makes good positioning particularly important on smaller urban and suburban sites.

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A unit placed immediately beside a neighbour's bedroom window could create considerably more difficulty than one located away from sensitive windows and garden areas.

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Heat pumps that provide heating and cooling

 

The 2025 planning changes also made it easier to install certain heat pumps that can provide cooling as well as heating.

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Previously, the permitted development rules were more restrictive in relation to cooling.

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Current rules allow qualifying air source heat pumps capable of both heating and cooling to potentially benefit from permitted development rights. However, equipment used solely for cooling does not qualify under these particular heat pump permitted development rights.

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This is particularly relevant to modern air-to-air heat pumps, which can provide efficient heating during winter and cooling during warmer weather.

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Heat pumps and existing wind turbines

 

There is another less obvious restriction that homeowners should be aware of.

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An air source heat pump installation will not qualify under these permitted development rights where there is an existing wind turbine on the building or within the property's curtilage.

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Additional heat pumps or wind turbines beyond the permitted allowances can require a planning application.

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For homeowners developing a wider renewable-energy strategy, the order in which different technologies are installed may therefore need consideration.

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Heat pump planning permission in conservation areas

 

Living in a conservation area does not automatically mean that you cannot install an air source heat pump.

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However, additional restrictions apply.

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Within a conservation area or World Heritage Site, an air source heat pump must not be installed on a wall or roof which fronts a highway, or positioned closer to a highway bounding the property than the building itself, if relying upon these permitted development rights.

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The visual impact of the installation therefore becomes particularly important.

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A discreet rear or side location may be significantly easier to accommodate than an external unit prominently visible from the street.

Local planning restrictions should also be checked.

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Heat pumps on listed buildings

 

Permitted development rights are more restricted for listed properties.

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Domestic air source heat pump permitted development rights do not apply to installations within the curtilage of a listed building or within a Scheduled Monument.

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A planning application and potentially Listed Building Consent may therefore need to be considered.

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Historic buildings require a more careful approach because the position of equipment, pipework, new openings and changes to historic fabric can all affect the significance and appearance of the property.

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Article 4 Directions and restricted permitted development rights

 

Not every house has the full range of normal permitted development rights.

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These rights can sometimes have been removed or restricted through:

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• an Article 4 Direction

• a condition attached to an earlier planning permission

• another planning restriction affecting the property.

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This means that homeowners should not rely simply on the fact that a neighbouring house has installed a similar heat pump.

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The planning history and restrictions affecting the individual property may be different.

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Ground source heat pump planning permission

 

Air source systems are not the only option.

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A ground source heat pump extracts heat from the ground using buried pipework, either through horizontal ground loops or vertical boreholes.

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On domestic premises, installing a ground source or water source heat pump is usually considered permitted development and therefore normally does not require a conventional planning application.

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However, additional considerations can arise with listed buildings, conservation areas and unusual or larger installations.

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Ground source systems can also involve substantial excavation or drilling, so planning permission is not necessarily the only approval that should be considered.

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For new ground source heat pump systems installed after 1 October 2023, an Environment Agency permit or exemption may also need to be investigated depending upon the type of system and circumstances.

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Air source or ground source?

 

The best heat pump system depends on the individual property.

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Air source heat pumps are usually easier and less disruptive to install because they do not require extensive ground works.

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Ground source heat pumps can provide an attractive alternative for properties with sufficient land or where boreholes can be accommodated.

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The decision may depend on:

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• available outside space

• garden size

• property type

• existing heating system

• heat demand

• insulation levels

• available electrical capacity

• installation budget

• planning and heritage constraints.

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A whole-home assessment can help determine which technology is most appropriate.

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When is heat pump planning permission required?

 

A planning application may need to be considered where the proposed installation falls outside the permitted development limits.

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Examples can include:

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• an oversized external unit

• too many heat pump units

• a pitched-roof installation

• certain installations affecting listed buildings

• locations that fail the permitted development requirements

• properties where permitted development rights have been removed

• installations which cannot comply with the required planning or noise standards.

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Requiring planning permission does not mean that a heat pump cannot be installed.

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It simply means the local planning authority needs to consider the proposal through a planning application.

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What might a heat pump planning application include?

 

Depending on the property and installation, a planning application may need information including:

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• a location plan

• site or block plan

• existing and proposed elevations

• position of the heat pump

• dimensions of the external unit

• manufacturer's specification

• noise information

• photographs of the property

• details of screening

• heritage information where appropriate.

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A clear set of drawings can be particularly useful because it allows the planning officer to understand exactly where the equipment will be positioned and how visible it will be.

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What if the heat pump is permitted development?

 

Where the proposed installation satisfies the permitted development requirements, a full planning application will normally not be necessary.

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Some homeowners may nevertheless want formal confirmation of the planning position before carrying out the work.

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In appropriate circumstances, a Lawful Development Certificate can provide formal confirmation that the proposed development is lawful.

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This can be useful where there is uncertainty or where the homeowner wants documentary evidence for the future.

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Heat pumps and Building Regulations

 

Planning permission and Building Regulations are separate matters.

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Even if an air source or ground source heat pump does not require planning permission, the installation must still comply with applicable Building Regulations requirements. Planning Portal confirms that both air source and ground source heat pump installations need to comply with Building Regulations.

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Electrical work, heating controls, energy efficiency and associated alterations may therefore all form part of the technical installation.

Using a suitably qualified installer is important.

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Consider the house before choosing the heat pump

 

A heat pump should ideally be considered as part of the wider performance of the home.

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Before installing one, it can be useful to look at:

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• loft and roof insulation

• wall insulation

• windows and doors

• draughts and air leakage

• radiator sizes

• underfloor heating

• hot water requirements

• ventilation

• solar panels

• battery storage

• electrical capacity.

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A well-designed heat pump system working in an efficient home can perform very differently from equipment selected without considering the building as a whole.

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Heat pumps as part of a green home upgrade

 

Heat pumps can form an important part of a wider move towards a more energy-efficient home.

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They can work particularly well alongside technologies and improvements including:

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• solar PV

• battery storage

• improved insulation

• efficient windows and doors

• smart heating controls

• underfloor heating

• mechanical ventilation

• EV charging.

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Planning these measures together can help homeowners avoid incompatible decisions and create a clearer long-term energy strategy.

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How APN Green Homes can help

 

APN Green Homes helps homeowners understand the practical steps involved in making their property greener, more efficient and better prepared for the future.

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For homeowners considering a heat pump, this can begin by looking at the property as a whole and identifying the most appropriate route forward.

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Where planning considerations arise, that can include establishing whether the proposed heat pump is likely to fall within permitted development rights or whether a planning application, Lawful Development Certificate or other consent should be considered.

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Planning a heat pump installation?

 

For most ordinary houses in England, the planning rules are now considerably more supportive of air source heat pump installations.

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The removal of the former one-metre boundary rule, the larger permitted unit size and the ability to install two qualifying heat pumps at detached houses have made permitted development available to many more homeowners.

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But the details still matter.

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Position, size, noise, property type, conservation status and existing planning restrictions should all be checked before installation begins.

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Considering an air source or ground source heat pump? APN Green Homes can help you understand the property, the planning position and how a heat pump could form part of your wider green home upgrade.

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NEXT STEPS

Every home is different, so the right next step depends on your property, your budget and what you want to achieve. APN Green Homes can help you turn the information you have just read into a practical plan for your own home. Whether you are considering one improvement or looking at a complete whole-home energy upgrade, we can help you understand what is suitable, what should be prioritised and where your money is likely to make the greatest difference.

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Choose one of the options below to get the ball rolling:

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BOOK A GREEN HOME SURVEY
Get a detailed assessment of your home with practical, property-specific recommendations and a clear plan for the improvements worth considering.

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BOOK A PHONE CONSULTATION
Talk through your property, ideas and priorities with us and get some initial direction on the best way forward.

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EMAIL US
Send us details of your property, photographs or any questions and we can advise you on the most appropriate next step.

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GIVE US A CALL
Prefer to speak to someone? Give us a call and tell us what you are hoping to achieve.

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Your greener, more efficient home starts with understanding the right improvements for your property — and putting them in the right order.