conditioning and equipment capable of providing both heating and cooling, such as an air-to-air heat pump.

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Planning Portal confirms that air conditioning capable of providing heating as well as cooling can potentially be treated as permitted development where all of the relevant air source heat pump requirements are satisfied. A system providing cooling only does not benefit from those specific permitted development rights.

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There is another important consideration.

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Government guidance issued in June 2026 states that, for a small home, planning permission will often not be required where an air conditioning installation does not materially affect the external appearance of the building. Whether an external condenser amounts to development requiring permission can therefore depend on the scale, position and appearance of the installation.

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For that reason, homeowners considering a cooling-only external system should establish the planning position before installation rather than simply assuming that it is permitted development.

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This article relates primarily to the planning system in England.

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Air conditioning permitted development

 

The phrase air conditioning permitted development can be slightly misleading because there is not simply one blanket permitted development right covering every domestic air conditioning unit.

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What matters is the function of the equipment.

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If the system works as an air source heat pump and provides heating, including a system that provides both heating and cooling, it may qualify under the permitted development rights for domestic air source heat pumps.

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The current Planning Portal guidance specifically states that an air source heat pump relying on these rights must not be used solely for cooling purposes.

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This distinction has become increasingly important because many modern split air conditioning systems are actually reversible air-to-air heat pumps.

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They can cool rooms during summer and reverse the refrigeration cycle to provide efficient heating during colder weather.

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Cooling-only air conditioning

 

A traditional air conditioning system designed only to cool the property does not qualify for the specific domestic air source heat pump permitted development right.

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Planning Portal's current guidance is clear that the heat-pump rights only apply where the system provides a heating function.

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However, that does not necessarily mean every small cooling-only installation automatically requires a planning application.

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In June 2026, the Ministry of Housing, Communities and Local Government clarified that air conditioning is not banned and stated that, in most cases, permission is not required for a small home where the installation would not materially affect the appearance of the building externally.

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The important point is that this becomes a matter of fact and degree.

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A small, discreet condenser hidden at the rear of a house may be very different in planning terms from several large units fixed prominently to the front or side elevation.

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Where cooling-only equipment is proposed externally, checking the position before installation is sensible.

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Air conditioning that provides heating and cooling

 

Modern air-to-air systems can be particularly attractive for green home upgrades because the same equipment can provide:

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• efficient heating

• summer cooling

• individual room temperature control

• rapid heating and cooling

• smart controls

• reduced reliance on traditional fossil-fuel heating.

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Since May 2025, qualifying air source heat pumps that provide both heating and cooling can potentially benefit from domestic permitted development rights in England. The legislation specifically prevents a qualifying unit from being used solely for cooling.

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This has made the distinction between an ordinary cooling-only air conditioning unit and a reversible air-to-air heat pump increasingly important when considering planning permission.

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Domestic air conditioning planning permission

 

For a typical house, the planning assessment should begin with four questions:

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Does the system provide heating as well as cooling?

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If yes, air source heat pump permitted development rights may potentially apply.

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Where will the external unit be installed?

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A discreet rear or side position may have considerably less planning impact than equipment prominently positioned on the front of the house.

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How large is the external unit?

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For qualifying air source heat pumps on a house, the outdoor compressor unit, including its housing, must not exceed 1.5 cubic metres to rely on the current permitted development right.

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Is the property subject to additional restrictions?

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Listed buildings, conservation areas, Article 4 Directions and previous planning conditions may affect what can be installed without permission.

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These questions should ideally be answered before equipment is ordered.

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Permitted development rules for heating and cooling units

 

Where an air conditioning system qualifies as an air source heat pump because it provides heating as well as cooling, a number of conditions must still be satisfied.

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Current domestic rules include:

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• compliance with the applicable MCS planning standard

• an outdoor compressor volume of no more than 1.5m³ for a house

• an outdoor compressor volume of no more than 0.6m³ for a qualifying block of flats

• restrictions on the number of permitted units

• restrictions on roof installations

• heritage restrictions

• requirements relating to external appearance and local amenity.

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From 28 May 2026, MCS 020a is the permitted certification standard identified by Planning Portal for qualifying domestic air source heat pump installations.

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The noise assessment associated with the system therefore remains an important part of the permitted development test.

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How many air conditioning units can be permitted development?

 

Where the equipment meets the definition and requirements of a qualifying air source heat pump, the number of units depends upon the type of property.

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

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For a house that is not detached, or a qualifying block of flats, generally only the first qualifying installation receives the permitted development right.

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This can be relevant where homeowners want several external condensers serving different areas of a larger property.

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A multi-split system using one external condenser to serve several internal units may therefore sometimes present a cleaner planning and visual solution than several separate outdoor units.

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Where should an external air conditioning unit be positioned?

 

Good positioning matters for both planning and performance.

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An external condenser should ideally be located where it can operate efficiently while minimising its effect on the property and neighbouring homes.

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Suitable considerations include:

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• distance from neighbouring bedroom windows

• visibility from the street

• access for maintenance

• airflow around the condenser

• pipe routes

• potential vibration

• noise

• proximity to patios and sitting areas

• appearance on the building.

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Where qualifying heat-pump permitted development rights are being used, Planning Portal requires the unit to be positioned, so far as practicable, to minimise its effect on both the external appearance of the building and the amenity of the surrounding area.

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A good installation therefore considers more than simply finding the shortest route from the indoor unit to the condenser.

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Air conditioning noise and planning

 

Noise is one of the most important considerations with external air conditioning equipment.

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Even relatively quiet modern units can become noticeable if positioned immediately beside:

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• a neighbour's bedroom

• a small enclosed garden

• a boundary wall

• a courtyard

• a balcony

• another noise-sensitive location.

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For qualifying air-to-air heat pump installations relying on permitted development, compliance with the MCS planning standard is required.

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Where a conventional air conditioning planning application is required, the local authority may also ask for manufacturer noise information or a more detailed noise assessment.

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This is particularly likely where the installation is close to neighbouring residential accommodation.

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Air conditioning near a property boundary

 

The former requirement for a domestic air source heat pump to be positioned at least one metre from a property boundary was removed as part of the planning changes that came into effect in May 2025.

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This means a qualifying heating-and-cooling heat pump can potentially be positioned closer to a boundary, provided all the remaining requirements are met.

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This change is particularly useful for:

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• terraced houses

• semi-detached properties

• narrow side passages

• smaller urban gardens.

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Nevertheless, positioning equipment immediately beside a neighbouring property should still be considered carefully because noise and amenity remain relevant.

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Can air conditioning be installed on a roof?

 

Roof installations need particular care.

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Under the domestic air source heat pump permitted development rules, an installation on a pitched roof is not permitted development.

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A qualifying installation on a flat roof may be possible, but every part of the heat pump must be at least one metre from the external edge of the roof.

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This can affect homes where there is little space at ground level and the homeowner is considering placing external equipment on:

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• an extension roof

• garage roof

• dormer

• flat-roofed rear addition.

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The visual effect from neighbouring properties should also be considered.

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Air conditioning planning permission in a conservation area

 

Air conditioning planning permission in a conservation area needs additional attention.

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Planning Portal's dedicated domestic air conditioning guidance advises that permission will be required where the home is in a protected area such as a conservation area.

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For systems falling within the air source heat pump regime, the detailed Class G rules also impose additional restrictions in conservation areas and World Heritage Sites.

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A qualifying air source heat pump must not be installed on a wall or roof which fronts a highway or be positioned closer to a highway bounding the property than the building itself.

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Because conservation-area controls and local restrictions can overlap, homeowners should check the individual property rather than assuming that the normal rules apply.

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A discreet rear location is generally likely to present fewer visual problems than a condenser prominently mounted on the principal elevation.

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Air conditioning on listed buildings

 

Listed buildings require a considerably more careful approach.

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The domestic air source heat pump permitted development right does not apply to installations within the curtilage of a listed building.

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Planning permission may therefore be required, and Listed Building Consent may also need consideration where the work affects the character or historic fabric of the listed property.

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Potential issues include:

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• fixing equipment onto historic walls

• drilling through original masonry

• external pipework

• cable routes

• condensate drainage

• prominent condenser units

• alterations to windows or openings.

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Alternative locations should therefore be explored before equipment is specified.

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What about flats and apartments?

 

Air conditioning for flats can be more complicated than for a conventional house.

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There may be several separate issues to consider:

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• planning permission

• freeholder consent

• lease restrictions

• management company approval

• external appearance

• noise affecting neighbouring flats

• access to suitable external space.

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The domestic air source heat pump rights can apply to a block consisting wholly of flats, subject to all of the relevant conditions, but the permitted outdoor compressor volume is smaller than for a house at 0.6 cubic metres.

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A block containing commercial premises as well as flats does not fall within that particular domestic definition.

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Leaseholders should therefore establish both the planning position and their right to alter the building.

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Article 4 Directions and planning restrictions

 

Permitted development rights are not guaranteed for every property.

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Planning Portal confirms that they may have been removed by:

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• a planning condition

• an Article 4 Direction

• another restriction affecting the property.

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This is particularly worth checking on:

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• newer housing developments

• conservation-area properties

• converted buildings

• architecturally sensitive estates.

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The fact that another property nearby has an air conditioning unit does not prove that the same installation will automatically be lawful on your home.

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When is an air conditioning planning application needed?

 

A planning application should be considered where the proposed installation amounts to development and does not benefit from an applicable permitted development right.

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Common examples can include:

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• cooling-only external air conditioning equipment

• equipment exceeding permitted heat-pump limits

• too many external units

• pitched-roof installations

• prominent locations

• listed-building situations

• properties with restricted permitted development rights

• installations that cannot meet the required standards.

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The current government position is that air conditioning is not banned and councils are expected to take a proportionate approach.

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Requiring planning permission therefore does not mean that the proposal is unacceptable.

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It means the council needs to consider the effect of the installation.

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What does an air conditioning planning application include?

 

The information required depends upon the property and installation, but a domestic application may include:

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• location plan

• site or block plan

• existing and proposed elevations

• precise condenser position

• unit dimensions

• manufacturer's specification

• noise information

• photographs

• proposed screening

• pipe and cable routes where relevant.

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A clear elevation drawing can be particularly useful because it shows exactly where the external condenser will appear on the property.

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For conservation-area or historic properties, additional design or heritage information may be necessary.

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Can air conditioning units be screened?

 

Screening can sometimes improve the visual appearance of external equipment, but it needs to be designed carefully.

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Possible approaches include:

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• planting

• purpose-made acoustic screens

• ventilated enclosures

• fencing

• carefully designed architectural screening.

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The condenser still needs sufficient airflow to operate efficiently.

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Completely enclosing an external unit simply to hide it can reduce performance and potentially increase noise.

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The screen itself may also have planning implications depending on its height and position.

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Do internal air conditioning units need planning permission?

 

The main planning concern with domestic air conditioning is normally the external equipment and any resulting change to the appearance of the building.

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Internal wall-mounted units by themselves will generally not create the same external planning issue.

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However, a typical split system also requires:

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• an external condenser

• pipes through the external wall

• electrical connections

• condensate drainage.

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It is therefore the complete installation that should be assessed.

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Air conditioning and Building Regulations

 

Planning permission and Building Regulations are separate matters.

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Planning Portal confirms that the installation of domestic air conditioning must comply with applicable Building Regulations.

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Depending upon the work, this can involve requirements relating to:

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• electrical safety

• energy efficiency

• ventilation

• penetrations through walls

• fire safety

• structural fixing.

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A system being permitted development does not remove the need to comply with other relevant regulations.

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Air conditioning and overheating

 

Cooling is becoming an increasingly important consideration in UK homes.

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Modern homes can sometimes experience significant summer overheating because of:

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• large areas of glazing

• highly insulated construction

• south- or west-facing rooms

• loft conversions

• reduced natural ventilation

• home offices

• internal electrical equipment.

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Building Regulations already require new residential buildings to be designed to minimise overheating, and the government confirmed in June 2026 that these requirements remain part of the wider approach to keeping homes comfortable during hot weather.

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Air conditioning can provide a solution, but it should ideally be considered alongside passive measures rather than automatically being the first response.

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Reduce overheating before increasing cooling demand

 

A greener approach to summer comfort can include considering:

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• external shading

• solar-control glazing

• blinds and shutters

• natural cross ventilation

• improved roof design

• MVHR with summer bypass

• reducing unnecessary internal heat gains

• insulation

• appropriate glazing design.

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These measures can reduce the amount of mechanical cooling needed.

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Where active cooling is still required, a highly efficient reversible heat pump can potentially provide both summer cooling and useful winter heating.

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Air conditioning and solar panels

 

Air conditioning has an interesting relationship with solar energy.

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The hottest and sunniest days — when air conditioning demand is highest — are also generally periods when a solar PV system can be generating significant electricity.

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That makes solar panels and air conditioning potentially complementary technologies.

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A wider home-energy system could combine:

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• solar PV

• air-to-air heat pumps

• battery storage

• smart energy controls

• EV charging.

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Solar-generated electricity can help offset some of the electricity consumed by cooling during sunny periods.

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Is a heating-and-cooling heat pump better than cooling-only air conditioning?

 

For many homeowners considering a new installation, it is worth comparing conventional cooling-only equipment with a reversible air-to-air heat pump.

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A reversible system can provide:

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• summer cooling

• winter heating

• individual room control

• rapid temperature response

• potentially greater year-round usefulness.

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It may also potentially benefit from the air source heat pump permitted development rights where all conditions are satisfied.

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The best solution depends on the house, existing heating arrangements and how the rooms will be used.

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Think about air conditioning as part of the whole home

 

Air conditioning should not necessarily be considered as an isolated appliance.

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A comfortable, efficient home involves the interaction between:

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• insulation

• glazing

• shading

• ventilation

• heating

• cooling

• solar generation

• battery storage

• smart controls.

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A room overheating because of excessive solar gain through poorly considered glazing may be better addressed through a combination of shading and cooling rather than simply fitting a larger air conditioner.

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A whole-home approach can therefore lead to a more efficient and comfortable result.

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How APN Green Homes can help

 

APN Green Homes helps homeowners consider energy, heating and cooling improvements as part of the wider performance of their property.

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For homeowners considering air conditioning, this can include looking at:

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• the type of system proposed

• whether heating as well as cooling is required

• suitable locations for external equipment

• planning constraints

• conservation-area considerations

• integration with solar energy

• other ways of reducing overheating.

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Where planning input is needed, the first step is to establish whether the proposed works are likely to require a planning application, potentially qualify as permitted development or need further confirmation from the local planning authority.

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Planning air conditioning for your home?

 

Air conditioning planning permission is not quite as simple as saying that every unit either needs permission or does not.

The type of system matters.

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A modern air-to-air heat pump that provides both heating and cooling may potentially qualify as permitted development, provided all the current conditions are satisfied. A cooling-only system does not benefit from those specific heat-pump rights, while very small installations may in some circumstances fall outside planning control where they do not materially affect the building's external appearance.

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Property type, equipment size, position, noise, conservation status and local restrictions should therefore all be considered before installation.

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Considering air conditioning or an air-to-air heat pump? APN Green Homes can help you understand the property, the planning position and the most appropriate route towards a cooler, more comfortable and energy-efficient home.

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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.