Air conditioning noise: what French law says in 2026 and how to settle a neighbour dispute
L'équipe Proclimo
17 Sep 2026 - 09 min read
"Ever since they put in their air conditioning, I can't sleep with the window open any more." Every summer, town halls, conciliation officers and civil courts see the same case file come back, replicated in hundreds of versions: an outdoor unit installed two metres from a bedroom, a compressor that kicks back in at 3 a.m., and two neighbours who no longer speak to each other.
The subject is rarely raised at the quotation stage. The installer mentions a "very quiet machine", the customer remembers the figure, and nobody stops to ask what the regulations actually say. Yet they are clear, they are quantified, and they apply just as much to the person installing as to the person putting up with the noise. With the explosion in the number of reversible air conditioners in France — boosted by the 5.5% VAT rate and the lighter administrative procedures introduced in 2026 — disputes are multiplying as a matter of course. Better to know the rules before you end up on the wrong side of them.
The core rule isn't a number of decibels, it's a difference
This is the most widespread misconception. Many homeowners go looking for the "legal decibel threshold" for an air conditioner. It doesn't exist in that form.
The Code de la santé publique (French Public Health Code, articles R. 1336-4 to R. 1336-13) doesn't work in absolute levels but in terms of emergence: the difference between the ambient noise with the appliance running and the residual noise without it, measured at the same spot, at the complainant's home.
The limit values for an activity or neighbourhood noise source are:
| Period | Maximum permitted emergence |
|---|---|
| Daytime (7 a.m. – 10 p.m.) | 5 dB(A) |
| Night-time (10 p.m. – 7 a.m.) | 3 dB(A) |
On top of this come correction terms linked to the cumulative running time over the period considered: the longer the appliance runs, the smaller the tolerance. An air conditioner running continuously all night — the typical case of an air-to-air heat pump in heating mode in winter — gets the harshest correction, often zero or close to it.
The practical consequence is crucial: an outdoor unit can be entirely unlawful while being objectively quiet. In a rural hamlet where the residual night-time noise drops to 25 dB(A), a compressor that pushes the ambient level up to 32 dB(A) creates an emergence of 7 dB: an offence. The same appliance beside a city boulevard, where the residual night-time level sits at 45 dB(A), will go completely unnoticed in regulatory terms.
Emergence is measured at the home of the neighbour making the complaint, with windows open or closed depending on the configuration — not at the foot of the machine.
You also need to distinguish this regime from that of behavioural noise (music, barking, DIY work), which falls under article R. 1336-5 and disturbance-of-the-peace rules. An air conditioner counts as equipment noise, subject to the emergence calculation.
What about the sound power figure quoted by the manufacturer?
On technical data sheets, two quantities sit side by side and cause confusion.
Sound power level (Lw), expressed in dB(A), characterises the total sound energy emitted by the machine. It is an intrinsic figure, independent of distance. Common domestic outdoor units are rated at 58 to 68 dB(A).
Sound pressure level (Lp) is what you actually hear at a given distance (often 1 m or 5 m). It's this much more flattering figure that brochures put front and centre.
A useful rule of thumb: in free field conditions, sound pressure falls by roughly 6 dB each time the distance doubles. A unit with a sound power of 62 dB(A) produces approximately 48 dB(A) at 1 metre, 42 dB(A) at 2 metres and 36 dB(A) at 4 metres. Hence the decisive importance of siting: doubling the distance to the property boundary is worth more than any acoustic enclosure.
Watch out for reverberation too. A unit placed in the corner between two walls, under a balcony or in a small courtyard can gain 3 to 6 dB(A) compared with the same machine in free field conditions. Confined spaces amplify.
What planning regulations say, on top of the noise rules
The Public Health Code isn't the only applicable text. Three further layers of rules stack on top.
The departmental sanitary regulations (RSD), issued by prefectoral order, often supplement the national framework with local detail on façade-mounted equipment.
The local urban plan (PLU) of the municipality may impose siting rules: a minimum setback from boundary lines, a ban on installation on a street-facing façade, an obligation to conceal the unit behind cladding. Some municipalities, particularly in protected areas or near a listed monument, flatly refuse units that are visible from public space. A prior works declaration remains required as soon as the external appearance is altered — the March 2026 simplification eased certain procedures relating to heat pumps, but it does not wipe out local planning easements.
The co-ownership rules (règlement de copropriété), finally, govern common areas and the external appearance of the building. Fitting a unit on a balcony, a façade or a roof terrace almost always requires authorisation from the general meeting, voted under the majority rule of article 25. An installation carried out without a vote exposes the owner to an action for restoration to the original state, regardless of the actual noise level.
I want to install one: the six decisions that head off a dispute
The best litigation is the kind you never start. Here are the points to settle before signing the quotation, not after.
1. Choose the location based on bedrooms, not on ease of installation. The installer will naturally look for the shortest refrigerant pipe run. Explicitly ask for a survey of neighbouring bedroom windows within a 10-metre radius, and favour a blank wall or a gable end.
2. Move it away and raise it up on suitable brackets. A setback of 3 to 4 metres from the boundary line changes everything. Quality anti-vibration wall brackets with rubber mounts cut structure-borne transmission through the wall — the kind that makes the downstairs neighbour's living room vibrate without anyone even hearing the compressor.
3. Never set a unit directly on a rigid slab without decoupling. Rubber anti-vibration mounts slipped under the machine's feet cost a few tens of euros and eliminate a large share of the low frequencies transmitted into the structure. It's the best value-for-money investment on the whole job.
4. Check the actual sound power figure on the product data sheet. The 2026 ranges from the major manufacturers go down to 55–58 dB(A) Lw on the smaller capacities. Insist on the numerical value in writing on the quotation, rather than a marketing claim of "ultra-quiet".
5. Switch on night mode ("Quiet", "Silent", "Night mode"). Present on almost every inverter model, it limits fan and compressor speed: you lose 5 to 15% of output and gain 3 to 6 dB(A). On an air-to-air heat pump running winter heating, this setting is often what tips the installation onto the right side of the law.
6. Tell your neighbour before the work starts. It isn't a legal obligation, it's the best insurance policy there is. A neighbour who has been informed and given a say on the location rarely objects; a neighbour presented with a fait accompli goes on the attack.
Acoustic screens: useful, but not magic
The enclosures and acoustic screens sold for outdoor units do work — provided two rules are respected. First, the screen must break the direct line of sight between the machine and the affected window: an obstacle that doesn't visually mask the source won't mask the noise either. Second, it must never obstruct airflow: an enclosure that is too tightly sealed recirculates hot air, wrecks the COP and triggers safety shutdowns on the machine.
A well-positioned outdoor acoustic panel, with at least 30 cm of clearance on the intake and discharge faces, typically delivers 5 to 10 dB(A) of attenuation. That's significant, but it will never make up for a disastrous siting decision.
I'm on the receiving end: a step-by-step approach
On the other side of the wall, you need to be methodical. A poorly built case file backfires on the complainant.
Step 1 — Document before you talk
Before making any contact, build a written record. A simple dated notebook is enough: start times, duration, weather conditions, the disturbance experienced. Keep it up for several weeks. Judges give real weight to the consistency and the track record of such observations.
To put objective numbers on it, a portable class 2 digital sound level meter gives a usable order of magnitude for a few tens of euros. Be warned: its readings have no evidential value in court — only an acoustic assessment carried out to the NF S 31-010 standard by a qualified consultancy carries legal weight. But they do let you find out whether your case stands up before you incur costs, and measure the residual noise while the machine is off.
For night-time measurement, a time-stamped portable digital audio recorder usefully complements the notebook, particularly for capturing winter defrost cycles, which have a very distinctive acoustic signature.
Step 2 — Direct contact, then a registered letter
Nine disputes out of ten are settled at this stage. Many owners have absolutely no idea their machine is causing a nuisance: they sleep on the other side of the house. Suggesting a concrete solution — switching on night mode, shifting the schedule, adding anti-vibration mounts — achieves far more than a blunt formal notice.
If talking it through fails, a registered letter with acknowledgement of receipt fixes the date of the complaint. It should be factual: a description of the nuisance, the periods concerned, a reminder of articles R. 1336-4 et seq. of the Public Health Code, and a request to bring the installation into compliance within a reasonable time (often one month).
Step 3 — The town hall and the conciliation officer
The mayor holds policing powers in matters of neighbourhood noise. A letter to the municipality's hygiene and health department (or to the ARS regional health agency in municipalities without a dedicated service) can trigger a visit and, where appropriate, an official acoustic measurement. Where an offence is established, the fine is that applying to class 3 petty offences (up to €450), together with an order to bring the installation into compliance.
In parallel, referring the matter to a conciliateur de justice (conciliation officer) is free of charge and, since the reform of civil procedure, is a mandatory preliminary step before any court action for neighbour disputes worth less than €5,000. Cerfa form no. 16042 is available on Service-Public.fr.
Step 4 — The civil court
If everything else fails, the action is based on abnormal neighbourhood disturbance (trouble anormal de voisinage), a case-law doctrine now codified in article 1253 of the Civil Code since the Act of 15 April 2024. Its advantage: it requires no fault on the neighbour's part. It is enough to show that the disturbance exceeds the ordinary inconveniences of neighbourhood life — even if the installation is entirely compliant and duly authorised.
The judge can order the unit to be removed or relocated, the installation of a mitigation device under a daily penalty, and the award of damages. Rulings handed down in recent years on heat pumps show growing firmness, particularly in quiet residential areas.
The special cases that come up most often
Co-ownership. If the unit is installed on a common area without general meeting approval, the co-owners' association can bring an action for restoration within a ten-year period. The affected neighbour would do well to approach the managing agent first, since that route is often quicker and cheaper than an individual lawsuit.
Tenants. A tenant can take action against a noisy neighbour like any other occupant. But if the noise comes from equipment installed by their own landlord, it is the landlord who must answer for peaceful enjoyment of the premises (article 6 of the Act of 6 July 1989).
Winter defrost noise. Many conflicts start in January, not July. In heating mode, an air-to-air heat pump reverses its cycle every 40 to 90 minutes to defrost the outdoor coil: the 4-way valve clacks, the fan stops abruptly, then restarts. This impulsive noise is far more disturbing than a steady hum — and perfectly measurable.
"I was here first." Contrary to a stubborn belief, prior occupancy offers no protection to whoever installed the unit. The pre-occupancy doctrine (article L. 113-8 of the Construction and Housing Code) covers only certain pre-existing agricultural, industrial or craft activities — not a domestic air conditioner.
In summary: five key reflexes
- The threshold is not absolute. What counts is emergence — 5 dB(A) by day, 3 dB(A) at night — measured at the complainant's home.
- Siting matters more than the machine. Distance, orientation, no reverberating corners: no accessory can make up for a bad location.
- Mechanical decoupling is the cheapest and most cost-effective measure. Anti-vibration mounts and brackets eliminate structure-borne transmission.
- Dialogue settles the vast majority of cases, and a case file documented in advance makes that dialogue credible.
- Abnormal neighbourhood disturbance applies even without fault: being administratively compliant is no shield against a court ruling against you.
To dig deeper, the Centre d'information sur le bruit (CidB) publishes free practical fact sheets on heating and air conditioning equipment, and the ministère de la Transition écologique makes the consolidated regulations available on Légifrance. On the prevention side, ADEME points out in its renovation guides that the acoustic criterion must appear in the specification for a heat pump installation, on the same footing as the SCOP.
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