Air conditioning condensers on commercial buildings
The permitted development right for plant applies to industrial and warehouse premises. On a high street unit, assume an application and a BS 4142 assessment.
Installing an external air conditioning condenser on a shop, restaurant, office or gym almost always needs consent, which is why air conditioning unit planning permission commercial enquiries are among the most common questions a high street business asks. The permitted development right for plant in the General Permitted Development Order 2015 applies to land used for an industrial process or as a warehouse. It does not extend to retail, food and drink, offices or leisure premises.
That one distinction decides most cases. If you occupy a unit on a parade, assume you are making an application, and budget for a noise assessment.
Whether external plant counts as development
Fixing a condenser to a wall or standing it on a roof is a building operation, and it alters the external appearance of the building. Where that alteration is material, it is development and needs permission unless a class covers it.
A small split unit tucked into an enclosed rear yard, invisible from any public vantage point, may not materially affect external appearance. That is a judgement, not a rule, and the only formal way to confirm that works are lawful is a certificate of lawfulness under section 192 of the Town and Country Planning Act 1990. Officers rarely argue about a single condenser in a back yard. They argue about four of them on a parapet.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.
The classes that can cover plant, and who they exclude
Part 7 of Schedule 2 to the GPDO 2015 contains the right to install, alter or replace plant and machinery, and it is tied to land used for an industrial process or as a warehouse. There are height limits and exclusions, including on designated land, so read the class before relying on it.
| Premises | Likely position for a condenser |
|---|---|
| Factory or warehouse | Part 7 plant right may apply, subject to height and designation limits |
| Shop, cafe, restaurant, takeaway | No plant class, planning application needed |
| Office or clinic | No plant class, planning application needed |
| Gym, soft play, leisure | No plant class, planning application needed |
| Any of the above, listed building | Application plus listed building consent where character is affected |
Air source heat pumps are a separate matter with their own classes in Part 14, carrying their own volume, siting and noise conditions, in the same way that solar panels on a house under Part 14 Class A have their own limits. A comfort cooling condenser is not a heat pump for those purposes, even where the equipment is physically similar, so do not borrow the microgeneration right for a cooling installation.
Temporary plant during construction sits under a different class again, covered in temporary buildings and plant during construction.
Roof-mounted units, height and the party wall
Roof mounting solves the visual problem and creates two others.
Height is the first. A unit on a flat roof reads from upper windows across the street and from any taller building nearby, and officers treat a run of condensers on a roof as a visual intrusion in a conservation area even where nobody at street level can see it. Set units back from the parapet, keep them below the parapet line where you can, and show a sightline section rather than asserting that they are not visible.
Structure and acoustics are the second. A roof deck transmits vibration into the building below, and the occupier of the flat above a restaurant will complain about structure-borne noise long before anyone complains about airborne noise. Anti-vibration mounts and an inertia base are standard and should appear on the submitted drawings.
Where the roof is shared, the Party Wall etc. Act 1996 may apply to the fixings and to any works to a party structure. That is a civil matter running alongside planning, and a party wall award does not authorise the development.
Noise assessed against the background sound level
Condenser noise is sound of a commercial nature, so BS 4142:2014+A1:2019 applies properly here. The method is to measure the existing background sound level, usually as the LA90, at the nearest noise-sensitive facade during the quietest period the plant will operate, then calculate the rating level of the plant at that position.
The rating level is the specific sound level plus corrections for acoustic features. A condenser fan with a tonal whine or an intermittent compressor attracts a correction, which is why the manufacturer's overall sound power figure on its own is never enough. Under the standard, a rating level around the background indicates a low impact, 5 dB above indicates an adverse effect and 10 dB above indicates a strongly adverse one, with context taken into account.
Councils commonly condition the outcome rather than the equipment, typically requiring that the rating level at the nearest residential window should not exceed the measured background by a stated margin, and often requiring it to sit 5 dB below background at night. That condition is what the installation has to be designed to meet, so get the Noise Impact Assessment done before you order plant rather than after. The assessment should be prepared or reviewed by a suitably qualified acoustician, and councils usually expect a member of the Institute of Acoustics.
Mitigation, roughly in order of what works: select quieter plant, run the fans at reduced speed at night, increase the distance to the receptor, build an acoustic enclosure or barrier with a solid line of sight break, add attenuators to any ducted element, then mount on anti-vibration fixings. Acoustic louvres on a plant screen do far more than a timber trellis.
The effect on a shopfront or street elevation
Councils refuse condensers on principal elevations routinely, and shopfront design guidance in most boroughs says plant should not be visible from the street.
Workable positions, in rough order of acceptability, are an enclosed rear yard at low level, a rear elevation behind a screen, a recessed roof plant area set back from the parapet, and a flank wall at high level where there is no public view. Unworkable: above a fascia, on a shopfront pilaster, on a window reveal to the front elevation, or anywhere a duct crosses a historic feature.
A short Planning Statement that explains why the chosen position is the least harmful of the options you tested does more than a long one about the operational need. Officers respond to evidence that alternatives were considered.
Conservation areas and listed buildings
In a conservation area the council must pay special attention to preserving or enhancing character under section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990, and visible plant on a principal elevation will usually be found harmful.
For a listed building, planning permission and listed building consent are separate applications and both may be needed. The fixings, the penetrations through walls or roofs, the condensate pipe route and the internal pipework all count, and consent can be refused on the basis of the internal interventions alone. Unauthorised works to a listed building are a criminal offence, which is worth saying plainly to any tenant who plans to install first and ask later.
Approaches that get through on sensitive buildings include siting plant in a rear lightwell or basement area, using a single larger unit instead of several small ones, routing pipework in existing service voids, choosing equipment that can be removed without permanent damage, and recording the position in a short heritage note so the council can see what is being affected.
What a full application should show
A complete submission for external plant contains more than a location plan.
- Existing and proposed elevations and a roof plan showing each unit to scale, with dimensions.
- A section or sightline drawing demonstrating visibility from the nearest public vantage point.
- Manufacturer data giving sound power levels by octave band, not just an overall figure.
- A BS 4142 assessment with the measurement position, date, times and background levels stated.
- Details of screening, enclosures, anti-vibration mounts and the proposed night-time operating mode.
- The condensate discharge and refrigerant pipe routes.
- For a kitchen, the extract and odour control arrangements, because the two systems are usually assessed together.
Include a maintenance access note. Councils increasingly ask how plant on a roof will be reached, and a scheme that needs a scaffold every year to clean a filter tends to stop being maintained.
Browse all 66 PlanScope report types to see which documents a plant installation is likely to need.
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Frequently asked questions
Do I need planning permission for an air conditioning unit on my shop?
Usually yes. The plant right in Part 7 of Schedule 2 to the GPDO 2015 is tied to land used for an industrial process or as a warehouse, so it does not cover shops, cafes, restaurants, offices or leisure premises. A single small condenser in an enclosed rear yard may not materially affect external appearance, but that is a judgement rather than a right.
How is condenser noise assessed?
Under BS 4142:2014+A1:2019. The background sound level is measured at the nearest noise-sensitive facade during the quietest operating period, and the plant's rating level is calculated at that position, including corrections for tonality and intermittency. A rating level around background indicates low impact, and 10 dB above indicates a strongly adverse effect.
Can I put condensers on the roof instead?
Often, and it usually helps visually, but roof mounting raises two new issues. Units read from upper windows and taller neighbouring buildings, so set them back from the parapet and provide a sightline section. And a roof deck transmits vibration into the space below, so anti-vibration mounts and an inertia base should appear on the drawings.
What about a listed building?
Planning permission and listed building consent are separate applications and both may be required. The fixings, wall or roof penetrations, condensate route and internal pipework all count, and consent can be refused on the internal interventions alone. Unauthorised works to a listed building are a criminal offence, so do not install first and apply later.
What does a council usually condition for external plant?
The outcome rather than the equipment. A typical condition requires that the rating level at the nearest residential window not exceed the measured background sound level by a stated margin, often requiring it to sit below background at night. Design the installation to meet that before ordering plant, because retrofitting attenuation is far more expensive.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.