Air Conditioning Noise and Your Neighbours: What the Law Says in 2026 and How to Avoid a Dispute
L'équipe Proclimo
14 Sep 2026 - 08 min read
"My neighbour had air conditioning installed this summer, and I've been hearing a constant hum from my bedroom ever since. Do I have any recourse?" Town halls, legal conciliators and building managers are hearing this question more and more often now that the 5.5% VAT rate has sent air-to-air heat pump installations through the roof. And the answer often surprises both sides: what settles the matter is not the decibel figure printed on the spec sheet, but the difference between the noise level with and without the appliance running. This is known as emergence, and the regulatory threshold is low: 5 dB(A) by day, 3 dB(A) at night.
In other words, an air conditioner that looks discreet on paper can be entirely unlawful in a quiet country cul-de-sac, while a noisier model will pass without issue alongside a busy boulevard. This article explains how the framework actually works, what you can demand, and above all the handful of installation choices that keep you out of court.
The text that actually applies: Article R.1336-5 of the Public Health Code
Many people believe there is a "30-decibel threshold" or a "legal 3-metre distance" for an outdoor unit. Neither exists in French national law.
The governing text is Article R.1336-5 of the Public Health Code (Code de la santé publique), introduced by Decree no. 2006-1099 on combating neighbourhood noise. It sets out a simple principle: no individual noise may, through its duration, repetition or intensity, disturb the peace of the neighbourhood. And it specifies a quantified criterion, emergence:
| Period | Maximum permissible overall emergence |
|---|---|
| Daytime (7 a.m. – 10 p.m.) | 5 dB(A) |
| Night-time (10 p.m. – 7 a.m.) | 3 dB(A) |
Emergence is the difference between the ambient level (background noise plus the air conditioner running) and the residual level (background noise alone, appliance switched off), measured at the complainant's home, first with the window open and then closed, in living rooms or on the terrace.
Two subtleties make all the difference in real cases:
- Duration-related correction terms. The longer the noise lasts over the reference period, the smaller the tolerance. An air conditioner running continuously for eight hours straight gets no correction at all: it is judged against the raw 5 or 3 dB(A). A unit that only runs for 20 minutes per hour may benefit from a correction of several decibels.
- The trigger threshold. A measurement is only required if the ambient level exceeds 30 dB(A) indoors or 40 dB(A) outdoors. Below that, no characterisable offence is deemed to exist.
A key point that is often overlooked: neighbourhood noise is not solely a matter for the Civil Code. It is a class 3 offence (a petty offence carrying a fixed fine of €68, up to €450), which can be formally recorded by a sworn officer from the town hall, the ARS or the municipal police — independently of any civil proceedings.
Why the decibel figures on the spec sheet prove nothing
On brochures from Daikin, Mitsubishi Electric, Atlantic or Toshiba, you'll see figures such as "48 dB(A)". That number is almost always the sound power level (denoted L_WA), standardised under EN 12102 — the total acoustic energy emitted by the machine, not what you hear from a distance.
What we perceive is the sound pressure level (L_pA), which depends on distance and surroundings. In a free field, it falls by roughly 6 dB(A) each time the distance doubles. As a rough guide, for an outdoor unit rated at 48 dB(A) sound power:
| Distance | Approximate sound pressure level |
|---|---|
| 1 m | ~40 dB(A) |
| 2 m | ~34 dB(A) |
| 4 m | ~28 dB(A) |
| 8 m | ~22 dB(A) |
On paper, everything is fine at 4 metres. Except that this calculation assumes a perfect free field. In real life:
- A unit installed against a wall gains about +3 dB(A) (reflection), in a corner +6 dB(A), and in a courtyard enclosed on three sides up to +9 dB(A).
- Night mode (silent mode) slows the fan and throttles the compressor: a real-world gain of 3 to 6 dB(A), but at the cost of roughly a third of the output.
- In heating mode in cold weather, defrost cycles produce abrupt bursts — the 4-way valve clicking, the fan revving up — which are far more irritating perceptually than a high average level. This is the number one source of winter complaints since air-to-air heat pumps became widespread.
Finally, the human ear is not a sound level meter. A low-frequency tonal compressor hum (around 50–100 Hz) is judged unbearable at a level where broadband whoosh would go unnoticed. Acoustic experts do in fact apply penalties for pronounced tonality in their reports.
Measure properly before you lose your temper
Before sending a registered letter, you need objective data. There are three levels of rigour, from the lightest to the most demanding.
1. The indicative self-assessment
A sound level meter app for smartphones gives you a rough idea, never proof: phone microphones saturate, aren't calibrated and don't apply A-weighting correctly. Keep it for personal diagnosis: "does the level really rise when the machine starts up?"
One step up, a class 2 digital sound level meter (budget €40 to €120) lets you record consistent differences between the appliance running and switched off. It still isn't legally binding, but a table of timestamped readings taken over two weeks carries considerable weight in an amicable approach — and shows your neighbour you aren't bluffing. Always note the time, the weather, the microphone position and how long the unit was running.
Keeping a bound log book with dates, durations and the disturbance experienced (night-time awakenings in particular) also serves as a nuisance diary: judges take these seriously, just as they do witness statements drawn up on the Cerfa 11527 form.
2. The free official assessment
The town hall or, in some municipalities, the municipal hygiene and health service (SCHS) can send out a sworn officer. Failing that, it is the ARS (regional health agency) that steps in. The measurement then follows standard NF S 31-010, under the complainant's conditions. It is free of charge and can lead to a formal notice from the mayor under his policing powers, or even to an official report.
The Centre d'information et de documentation sur le bruit (CIDB) publishes very clear fact sheets on the procedure to follow, and Bruitparif provides useful data for the Île-de-France region.
3. A private acoustic survey
An acoustic consultancy will typically charge €500 to €1,200 for a report compliant with NF S 31-010, including an emergence calculation, duration corrections and a tonality penalty. This is the document that carries weight before the judicial court — and the cost can be charged to the losing party.
The amicable route, which settles 80% of cases
Nobody wants to sue the neighbour across the landing. In practice, most disputes are resolved through an inexpensive technical modification.
Step 1 — Direct conversation. Many owners genuinely have no idea their unit is a nuisance: they can't hear it from their living room. Invite them to listen from your place, at 11 p.m. That is often decisive.
Step 2 — The registered letter. Factual, dated, free of invective: a recap of your readings, a reference to Article R.1336-5 of the Public Health Code, proposed concrete solutions and a reasonable deadline (one month).
Step 3 — The legal conciliator. Free of charge, and you can apply online via the Ministry of Justice website or at the town hall. Since the reforms to civil procedure, this prior attempt at amicable resolution is mandatory for neighbour disputes before taking the matter to a judge — except in emergencies. Don't skip it: your summons would be inadmissible.
Step 4 — In a co-owned building, the managing agent. If the outdoor unit is fixed to a common part (façade, balcony railing, roof terrace), it will normally have required authorisation from a general meeting, usually by the majority set out in Article 25 of the Law of 10 July 1965. Installing it without authorisation exposes the owner to an action for restoration, which remains actionable for ten years. The co-ownership rules may also include a "quiet enjoyment" clause or prohibit any alteration to the building's external appearance: read them first.
Step 5 — The judicial court. On the basis of abnormal neighbourhood nuisance, now codified in Article 1253 of the Civil Code since the Law of 15 April 2024. The judge can order the unit to be relocated, an acoustic enclosure to be fitted, operating hours to be restricted, and can award damages. Note that case law does not necessarily require the emergence limit to be exceeded in order to establish nuisance — duration, repetition and tonality are sometimes enough.
The real issue: installing so you never get there
For the owner, everything comes down to the installation itself. Experienced refrigeration engineers say it plainly: 90% of disputes stem from the location, not the machine.
Choosing the location
- Keep the unit as far as possible from your neighbour's openings (bedroom window, terrace). There is no national legal minimum distance, but some local planning rules (PLU) and housing estate covenants impose setbacks — check with the town hall before ordering.
- Never blow air towards the boundary line. Direct the airflow parallel to the fence, never perpendicular towards the neighbouring property.
- Avoid recessed corners, enclosed courtyards and walkways: these act as natural amplifiers.
- Avoid ground-mounting against a façade that directly backs onto a bedroom: structure-borne noise (vibrations transmitted through the building fabric) travels through the wall far more readily than airborne noise.
Decouple mechanically
The most cost-effective part of the anti-noise budget, and often the most neglected.
- Rubber anti-vibration mounts (silent blocks) fitted between the unit's chassis and its support eliminate most of the transmitted vibration. Negligible cost, immediate effect on low-frequency hum.
- A solid ground support (concrete slab or heavy blocks) is almost always preferable to a wall bracket, which turns the façade into a soundboard. If a bracket is unavoidable, it should be oversized and mounted on dampers.
- Refrigerant lines and the condensate pipe should be secured with rubber-lined clips, never rigidly into the wall.
Treat the acoustics
- An acoustic screen for the outdoor unit — a solid, heavy panel extending 30 cm beyond the machine on each side and placed at least 30 cm from the air outlet — delivers 5 to 10 dB(A) in the neighbour's direction. Be careful: a badly designed enclosure stifles the appliance, drives down efficiency and can cause air recirculation that trips safety cut-outs. Always respect the manufacturer's clearances.
- Outdoor absorbent acoustic panels applied to the wall behind the unit reduce reflections in narrow courtyards.
- Indoors, if the disturbance comes from your own split system, a window sealing strip or simply a heavy curtain over the window nearest the outdoor unit already changes night-time perception.
Control it intelligently
A smart thermostat compatible with air conditioning, or simply the manufacturer's Wi-Fi module, lets you schedule silent mode between 10 p.m. and 7 a.m., cap night-time output and avoid sharp full-speed start-ups. On a correctly sized inverter unit, the machine runs continuously at low speed rather than cycling — which is far easier on the neighbourhood acoustically, and cheaper to run.
Key takeaways
- The legal criterion is not an absolute decibel figure but emergence: 5 dB(A) from 7 a.m. to 10 p.m., 3 dB(A) at night (Article R.1336-5 of the Public Health Code).
- The dB(A) figure in the brochure is a sound power level, not what the neighbour hears. The surroundings (wall, corner, courtyard) can add 3 to 9 dB(A).
- An official measurement by the town hall, the SCHS or the ARS is free; a private survey costs €500 to €1,200 but is admissible in court.
- Attempting conciliation is mandatory before suing over a neighbour dispute.
- In a co-owned building, a unit on a common part without general meeting authorisation can be challenged regardless of any noise issue.
- On the installation side, location, anti-vibration decoupling and airflow orientation solve almost every problem — for a few dozen euros at the time of fitting, versus several thousand if the unit has to be removed.
Sources and resources: Code de la santé publique (art. R.1336-5 et seq.), Decree no. 2006-1099, Article 1253 of the Civil Code (Law no. 2024-346 of 15 April 2024), standard NF S 31-010, Law no. 65-557 of 10 July 1965 on co-ownership, Centre d'information et de documentation sur le bruit (CIDB), Service-Public.fr, Bruitparif.
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