Dutch heat pump noise limits: 40 and 45 dB explained (Bbl)

As heat pumps appear in Dutch gardens en masse, outdoor-unit noise has become one of the most common neighbour complaints. The legislator has set clear limits. This page explains which limits apply, where exactly the sound is assessed, and what happens when an installation is too loud. Want to know right away whether a setup complies? Use the free calculator.

Which law applies?

Since 1 January 2024 the noise requirements for outdoor heat and cold generation installations — heat pumps and air conditioners alike — are part of the Besluit bouwwerken leefomgeving (Bbl), under the Dutch Environment Act. The Bbl succeeds the Building Decree 2012; the noise rules were carried over unchanged. They were originally introduced on 1 April 2021 and apply to installations placed or replaced since then.

The two core provisions are article 4.107(2) Bbl (dwellings on different plots: the limit applies at the plot boundary) and article 4.108(3) Bbl (dwellings on the same plot, such as apartments: the limit applies at openable windows and doors of the other dwelling). The calculation method is laid down in the Omgevingsregeling.

The limits: 40 dB and 45 dB

The base limit is 40 dB(A), applicable in the evening and night period from 19:00 to 07:00 — the hours when people sit outside, sleep, and background noise is low. During the day (07:00–19:00) the level may be 45 dB(A), but only if the unit has a low-noise setting (silent mode) active in the evening and night. Without silent mode, the unit must meet 40 dB day and night.

For reference: 40 dB corresponds to a quiet residential street at night or a silent library. It is explicitly not an inaudibility requirement — a compliant heat pump can still be audible at the boundary, particularly the low hum of fan and compressor.

Where is the sound assessed?

For dwellings on different plots, the assessment point is at the boundary with the neighbouring plot, at 1.5 metres height. Importantly, the limit only applies at boundaries with plots where a residential function exists or is possible. If your garden borders a business site, public road or green, no limit applies on that side.

Two special situations matter. If a fully closed screen or garden wall of at least 10 kg/m² stands on the boundary, the sound is assessed half a metre above that screen, with a 5 dB correction. And if the outdoor unit is mounted high — on an extension, shed or roof — the sound must additionally be assessed at openable windows and doors of neighbouring dwellings, at the actual height of those windows. In practice those elevated points often govern.

Which installations are covered?

The requirement covers all outdoor heat or cold generation installations at dwellings: air-to-water heat pumps, hybrid heat pumps, air-to-air heat pumps and air-conditioning outdoor units. It applies per individual installation, to units placed or replaced on or after 1 April 2021. Older installations are not covered retroactively, but in cases of serious nuisance the municipality can still demand measures under the general duty of care.

How is the level determined?

The law prescribes a calculation method (laid down in the Omgevingsregeling). The national WPAC-geluid tool was developed for this: from the unit's sound power (LwA, on the energy label or product documentation), the distance to the assessment point, reflections, screening and the mounting situation, it computes the level at the assessment point. The interactive calculator on this site is based on the same method and shows directly which sound power is allowable at a given spot.

Enforcement: what if an installation is too loud?

Supervision and enforcement rest with the municipality (often executed by the regional environment service). Anyone experiencing nuisance can request enforcement; the municipality can commission a measurement or calculation and, if the limit is exceeded, require the owner to take measures — from activating silent mode to relocating the unit. Experiencing nuisance from a neighbour's installation? See the step-by-step guide on noise nuisance from the neighbours' heat pump.

Conversely: if you are installing a heat pump, make and keep the noise calculation before installation. Many installers supply it as standard; with the calculator you can verify it yourself and share the result with installer, neighbours or municipality via the share button.

Dutch heat pump noise limits: the 40 and 45 dB rules explained