heat pump noise measurement

Heat pump noise measurement: independent testing against the standard

A heat pump may produce no more than 40 dB(A) at the property boundary with an adjacent plot that has a residential function. For apartments and other homes on the same plot, the limit applies at an openable window or door. This is set out in the Dutch Building Decree (Besluit bouwwerken leefomgeving, articles 4.107 and 4.108 BBL). If the sound contains an audible tone, such as a hum, the determination method adds a correction of 0 to 6 dB to the measured level, depending on how pronounced the tone is. Does your neighbours' heat pump exceed this standard? With a calibrated Class 1 measurement we independently assess the noise and deliver a legally usable report that stands up before the municipality and in court.

from € 1.098 excl. VAT

Many Dutch legal expenses insurers reimburse the cost in full or in part.

Schedule free consultation or call +31 (0)20 808 70 90

The noise standard for heat pumps: 40 dB(A)

Since 1 April 2021 a statutory noise limit has applied to the outdoor unit of a heat pump or air conditioner. The noise level may not exceed 40 dB(A), measured at the property boundary with an adjacent plot that has a residential function or, for apartments, at an openable window or door. This new-build requirement is set out in the Dutch Building Decree (Besluit bouwwerken leefomgeving, BBL), which has fallen under the Environment and Planning Act since 2024. The old Activiteitenbesluit is no longer the governing framework for this situation.

Where we measure depends on the situation. If the dwellings are on separate plots, article 4.107(2) BBL applies and we measure at the property boundary. If the dwellings are on the same plot, or if they are apartments, article 4.108(3) BBL applies and we measure at the position of an openable window or door. The determination method is set out in article 5.59 and annex XVII of the Environment Regulation (Omgevingsregeling). If the sound contains an audible tone, this determination method adds a correction of 0 to 6 dB to the measured level, depending on how pronounced the tone is. The same 40 dB(A) as for new builds also applies in the case of a renovation, for example when the neighbours have a heat pump installed at their existing home (article 5.14(2) BBL).

How we measure heat pump noise

We measure with a calibrated Class 1 sound level meter (Svantek SV 971A), the highest accuracy level the standards prescribe. We determine the measurement point according to the situation: at the property boundary, or at an openable window or door. That way the report exactly matches the correct determination method from the BBL. The assessment itself follows the determination method from annex XVII of the Environment Regulation, including the correction of 0 to 6 dB for tonal noise.

Heat pump noise is often tonal, a constant hum at low frequency that is most disturbing at night. If a tone is suspected, we carry out a narrow-band frequency analysis (FFT) in accordance with NEN-ISO 1996-2:2017, Annex J. The audibility of the tone determines the correction of 0 to 6 dB. We also record the background level, so that we can cleanly isolate the noise of the installation. If necessary we supplement this with a low-frequency noise survey. We take the same approach to measuring air conditioning noise.

What does a heat pump noise measurement cost?

An acoustic assessment based on your drawing and the product data of the heat pump costs from 1,098 euros excluding VAT. If a measurement on site proves necessary, for example in a borderline case close to the standard of 40 dB(A), the full process costs 2,598 euros excluding VAT. In both cases you receive a complete, independent report that has been tested against the statutory standards and that you can use in dealings with the municipality or in court.

In many cases these costs are reimbursed through legal expenses insurance, because the measurement provides the evidence in a dispute about unlawful nuisance. It pays to check this with your insurer in advance. We are happy to advise you on the options for a measurement via your legal expenses insurance. KGI Groep is an independent consultancy: we do not sell insulation materials or enclosures, which keeps our report neutral and focused purely on the measurement.

Case study: from 47 to 33 dB(A)

In a recent case in Haarlem a resident reported serious disturbance from the neighbours' heat pump. Our measurement confirmed the problem: the outdoor unit produced 47 dB(A) at the assessment point, well above the limit of 40 dB(A). Based on our report a sound-insulating enclosure was installed.

The follow-up measurement showed that the enclosure was effective: the noise level had dropped to 33 dB(A), well below the standard. This case shows that an objective measurement first establishes the scale of the problem and then demonstrates that the chosen solution really works. Without a measurement it remains guesswork whether a measure is sufficient.

Solutions when the standard is exceeded

If the standard is exceeded, a correctly dimensioned sound-insulating enclosure is often the most effective measure. Such an enclosure reduces the noise by 10 to 20 dB, enough to bring a heat pump that measures just above, or well above, 40 dB(A) back within the standard.

Ventilation is crucial here. An enclosure must not obstruct the air supply to the outdoor unit, or the unit will overheat and its efficiency will drop. We calculate how much noise reduction is needed and advise on a solution that keeps the ventilation intact. Because we do not sell products, that advice is independent. Besides an enclosure, vibration dampers, a different mounting position or a noise screen can also help.

The two legal routes for heat pump disturbance

If your neighbours' heat pump exceeds the standard, you have two routes. You can ask the municipality to take enforcement action over the breach of the BBL. An independent measurement report substantiates that request and prevents your complaint from being brushed aside for lack of objective evidence.

You can also bring civil proceedings for unlawful nuisance (article 5:37 Dutch Civil Code). In that case too our measurement report is the evidence: it demonstrates in black and white that the standard is being exceeded. We have been delivering legally usable reports since 1994 and have now produced more than 10,000 of them. If you need a permit, or supporting evidence for the municipality, we also carry out an acoustic survey for permits.

What the court weighs up in heat pump noise cases

In disputes about heat pump noise the court does not look at how disturbing the resident finds the noise, but at whether the statutory limit of 40 dB(A) is genuinely exceeded. Unlike for hospitality venues and businesses, where the environmental plan sets a more lenient daytime standard and a stricter night-time standard, the BBL sets one fixed limit for the outdoor unit. What is decisive is whether a correct measurement at the right assessment point has demonstrated that the installation exceeds it.

This is also clear from recent case law. In rulings by the District Court of North Holland (ECLI:NL:RBNHO:2023:10412) and the District Court of Zeeland-West-Brabant (ECLI:NL:RBZWB:2024:313) about the outdoor unit of a heat pump, the central question in each case was whether a measurement following the prescribed determination method had demonstrated that the 40 dB(A) standard was exceeded. The mere fact that the neighbours can hear the installation is legally insufficient. An independent measurement report that precisely follows the determination method from the BBL therefore makes the difference between a strong case and a hopeless one.

Measuring the noise yourself with an app versus a professional measurement

A noise app on your phone gives an indication, but no evidence. The microphone of a smartphone is not calibrated and does not measure in Class 1. How far the reading is off varies by phone and by app, and the difference can be considerable. An app also lacks the frequency analysis needed to determine the correction for an audible tone.

In a conversation with the neighbours an app can help to back up your suspicion. But the municipality and the court accept only a measurement with a calibrated Class 1 meter, carried out at the right measurement point in accordance with the determination method from the BBL. Only then is the report legally usable. We assist private individuals as well as businesses.

Cost

from € 1.098 excl. VAT

This amount covers the calculated assessment against the 40 dB(A) limit at the property boundary, based on your drawing and the manufacturer's sound data. If an on-site measurement turns out to be necessary, for instance in a borderline case close to the limit, that route costs 2,598 euros excluding VAT. We always discuss this with you in advance.

Many Dutch legal expenses insurers reimburse the cost in full or in part.

Request a quote for your situation

FAQ

Frequently asked questions

How many decibels may a heat pump produce at a neighbouring property?

At the boundary with an adjacent plot that has a residential function, the outdoor unit of a heat pump or air conditioner may cause no more than 40 dB(A) (article 4.107(2) BBL). If the dwellings are on the same plot, as with apartments, the 40 dB(A) applies at an openable window or door of the neighbours' home (article 4.108(3) BBL). If the sound contains an audible tone, a correction of 0 to 6 dB is added. The same 40 dB(A) applies in the case of a renovation.

What does a heat pump noise measurement cost?

An acoustic assessment based on your drawing and the product data costs from 1,098 euros excluding VAT. If a measurement on site is needed, the full process costs 2,598 euros excluding VAT. In both cases you receive an independent report that has been tested against the statutory standards. In many cases legal expenses insurance reimburses these costs, so check this with your insurer in advance.

What can I do about my neighbours' humming heat pump?

First have the noise measured objectively with a Class 1 meter. If a tone is suspected, we carry out a narrow-band frequency analysis (FFT) in accordance with NEN-ISO 1996-2:2017, Annex J. The audibility of the tone determines the correction of 0 to 6 dB. If the installation exceeds the standard of 40 dB(A), you can ask the municipality to take enforcement action, or bring civil proceedings. A correctly dimensioned enclosure often reduces the hum by 10 to 20 dB, provided ventilation remains unobstructed.

Does my insurance reimburse a noise measurement?

Often it does. Legal expenses insurance policies regularly reimburse the cost of a noise measurement, because the report provides the evidence in a dispute about unlawful nuisance. Check this with your insurer in advance. We are happy to advise you on the options.

How do you measure heat pump noise correctly?

With a calibrated Class 1 sound level meter at the right measurement point: at the property boundary for dwellings on separate plots, or at an openable window or door for apartments. If a tone is suspected, we carry out a narrow-band frequency analysis (FFT) in accordance with NEN-ISO 1996-2:2017, Annex J. The audibility of the tone determines the correction of 0 to 6 dB. The assessment follows annex XVII of the Environment Regulation.

Can I measure heat pump noise myself with an app?

For a first impression you can, but an app is not evidence. The microphone of a phone is not calibrated and does not measure in Class 1; how far the reading is off varies by phone and by app. An app also lacks the narrow-band frequency analysis (FFT) for the tonal correction. Only a professional measurement with a Class 1 meter is legally usable.

Contact

Consultation or direct quote

Schedule a free consultation or request a direct quote via the form. We respond within one business day.

+31 (0)20 808 70 90

info@kgigroep.nl

Keizersgracht 241
1016 EA Amsterdam