A new air-to-water heat pump must comply with the planning values of the federal noise protection ordinance (LSV) for neighbours – in purely residential zones typically 45 dB(A) at night at the open window of noise-sensitive rooms. This is proven with the noise protection proof, which in the Canton of Zurich is part of the registration with the municipality. With correct placement and a modern device, this can be achieved without any problems in the vast majority of cases.
Key points in brief
- Federal law is decisive: the noise protection ordinance (LSV) with its planning values for new installations – assessed according to Annex 6 (industrial and commercial noise).
- The night is almost always critical: The heat pump also runs at 3 a.m., and the lower limit values apply at night.
- The noise protection proof (standardised form, e.g. via FWS web tool) is part of the municipality's notification or permit procedure in the Canton of Zurich.
- Measurements are not taken at the device, but at the neighbour's – at the open window of the nearest noise-sensitive room.
- The three most effective levers: quiet device, smart placement, night mode.
Which limit values apply to heat pumps?
Heat pumps installed outdoors (and outdoor units of split systems) are considered new stationary installations under noise law. The stricter of the two LSV standards applies to them: the planning values – not just the immission limit values. The assessment is based on Annex 6 of the LSV, depending on the noise sensitivity level (ES) of the zone in which the neighbouring property is located:
| Sensitivity level | Typical zone | Planning value day | Planning value night |
|---|---|---|---|
| ES I | Recreation zones | 50 dB(A) | 40 dB(A) |
| ES II | Purely residential zone | 55 dB(A) | 45 dB(A) |
| ES III | Residential/commercial zone (mixed) | 60 dB(A) | 50 dB(A) |
| ES IV | Industrial zone | 65 dB(A) | 55 dB(A) |
Values according to Annex 6 LSV (exposure limit values); rating level incl. corrections. The current version of the LSV and the zoning of your municipality are decisive.
Two points that make the difference in practice: Firstly, the value at the neighbour's counts – at the open window of the nearest noise-sensitive room (bedroom, living room), not directly at the device. Secondly, the measured level is not compared raw: Surcharges flow into the assessment, for example for tonal noise components. A device that appears quiet on paper can lie above the limit value after corrections – exactly for this reason there is the standardised proof.
What is the noise protection proof – and when is it needed?
The noise protection proof is the standardised form used to prove that the planned heat pump complies with the planning values at the specific location. The basis is the enforcement aid of the Cercle Bruit, the association of cantonal noise protection agencies; the specialist association Wärmepumpen Schweiz (FWS) provides a web tool for this that directly integrates device data from the manufacturers.
In the Canton of Zurich, this proof is part of the registration of the heating replacement with the municipality – regardless of whether the project runs in the notification procedure or needs a building permit (the demarcation is covered in Permit for heat pumps). The following are included: sound power of the device, distance to the relevant window, installation situation (free, on wall, in corner – reflections increase the level), any operating modes.
Important for understanding roles: The building owner is responsible for compliance – in practice, the proof is created by the specialist company that plans the system. At ecoEn, it is part of the standard scope of every heat pump project.
How loud is a modern heat pump anyway?
Significantly quieter than their reputation. Modern air-to-water devices from good manufacturers have audibly improved in recent years – quieter fans, better encapsulation, speed-controlled compressors. Added to this are night modes that reduce the speed and thus noise in the critical hours.
Nevertheless: "Quiet" is not a brochure value, but a location result. The same device can easily pass at one location and fail at another – because of a three-metre difference in distance or a reflecting corner of a house. That is why noise protection starts with placement, not with the data sheet. How we concretely assess locations is shown in Noise & location choice.
The most effective measures against noise problems
We think them through in this order for every planning:
1. Placement: as far away from neighbouring bedrooms as possible, not in sound-amplifying corners or narrow passages between buildings, exhaust direction not towards the relevant window. 2. Choice of device: a quiet device often costs only a little more – and saves any discussion at the limit value. 3. Operating mode: configure night setback or silent mode – it is not always active ex works. 4. Structural measures: soundproof hood or wall as a supplement if the first three levers are not enough – not as a substitute for good planning. 5. Indoor installation to be checked as an alternative: If the heat pump is in the cellar, the topic shifts to air ducts and structure-borne noise – solvable, but also planning work.
And an underestimated point: the conversation with the neighbour before construction. Legally not required, practically worth its weight in gold – most noise conflicts do not arise from decibels, but from surprise.
What happens in the event of a neighbour's complaint?
If a neighbour complains after commissioning, the municipality checks as the enforcement authority – the basis is again the LSV and proof. If the system complies with the values, the case is legally clear; if it lies above, remediation measures can be ordered, from operating mode to soundproof wall. The best protection against this is a clean, conservatively calculated proof before construction – not a tight one.
From our experience, the most delicate locations are not the narrow terraced house neighbourhoods – there, planning is done carefully right from the start. They are the supposedly uncritical locations: lots of space, so the device is placed where the pipe is shortest – directly under the neighbour's guest room window, in a reflecting corner. A three-metre offset would have solved the issue. That is why the noise question is part of the first site visit with us, not the last planning round.
Frequently asked questions
Do I need a noise protection proof for every heat pump?
For outdoor devices and split devices practically always – in the Canton of Zurich it belongs to the registration with the municipality. For pure indoor installation, the proof is generally omitted, but the noise question (ducts, structure-borne noise) remains part of clean planning.
Which sensitivity level applies to me?
This is determined by the building and zoning regulations of your municipality – typical single-family home neighbourhoods are ES II, mixed zones ES III. We clarify the assignment during planning; it decides on the relevant limit value.
Is it enough if the device is considered quiet in the brochure?
No. The decisive factor is the calculated rating level at the neighbour's window – including distance, reflections and surcharges. A quiet device helps, but replaces neither proof nor smart placement.
My neighbour already has concerns before construction – what to do?
Take them seriously and involve them: show location, explain proof, perhaps choose the quieter device type. A conversation before construction costs half an hour; a conflict afterwards costs nerves and at worst retrofitting.
Do the same rules apply to geothermal probe heat pumps?
Brine-to-water devices are located inside and are practically inaudible outside – the noise issue largely falls away. On the other hand, the geothermal probe needs its own permit; more on this under Geothermal probe: process & permit.
Free initial consultation
Heat pump planned? We include noise in our thoughts right from the start.
Location assessment, quiet choice of device and noise protection proof belong to the standard scope at ecoEn. Free of charge and without obligation.
Prefer to talk? +41 78 830 83 35
Heat pump Zurich – heating replacement from a specialist company →
Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Noise protection ordinance (LSV, SR 814.41) Annex 6, Cercle Bruit (enforcement aid air/water heat pumps), FWS – Fachvereinigung Wärmepumpen Schweiz (noise protection proof tool), municipal enforcement Canton of Zurich.
Last updated: 9 July 2026 · Author: ecoEn editorial team
