WarmtepompGeluid
Evening+Night
54
Day
59
dB(A) max LwA

Property

Residential zoning

Outdoor unit

Zb = 1.15 m · Q = 2

Margin

3 dB

Sound power

Buildings

Garden walls

Left
Right

Receiver positions

No receiver positions. Click '+ Receiver position' on the map to add one.

Result

Evening+Night
54
dB(A) max LwA
Day
59
dB(A) max LwA
Qbron = 2 · Margin = 3 dB
Max Lp at boundary: 34 dB(A)
(at LwA = 51)
Side cross-section
Side cross-section — Shows the height of buildings and the sight line from the outdoor unit to the loudest point on the property boundary. There is a clear line of sight between the outdoor unit and the measurement point.

Calculate heat pump noise: outdoor unit in the garden

An outdoor unit at ground level in the garden is the most common setup for terraced and semi-detached houses, and usually the most favourable one: the unit sits low, so garden walls can screen the sound and it reaches the neighbours’ windows less easily. Even so, the 40 dB limit at the property boundary is exceeded faster than many people expect — especially on narrow plots where the side boundary may be only two or three metres away.

Use the interactive map above to drag the unit around your garden and instantly see where the boundary level is too high (red) or compliant (green). The result is the maximum sound power (LwA) a unit may have at that spot.

How to use the tool for this situation

  1. 1
    Set up the property

    Enter the width and depth of your garden and tick which sides border a residential plot. Sides without residential zoning (a road or public green, for example) carry no noise requirement.

  2. 2
    Drag the unit into place

    The black HP marker is the outdoor unit. Drag it and watch the numbers along the boundary change. The red dashed line is the 40 dB contour.

  3. 3
    Try a garden wall

    Enable a screen on the left or right boundary under “Garden walls”. A closed wall of at least 10 kg/m² moves the assessment point above the wall, which in practice yields about 5 dB of headroom.

  4. 4
    Read the result

    The panel shows the maximum allowable LwA for evening/night and day. Compare it with the sound power of the unit you are considering (enter it under “Equipment specs” for a direct pass/fail check).

Distance to the boundary dominates

For a garden installation, distance to the nearest boundary is by far the most important lever. Every doubling of distance buys 6 dB: a unit 4 metres from the boundary may have 6 dB more sound power than the same unit at 2 metres. In a 5-metre-wide garden the unit can never be more than 2.5 metres from a side boundary — in that case the centre of the garden, a quieter unit or a garden wall is often the only route to 40 dB.

Watch out for corner effects too: a unit within 2.5 metres of your own facade gets directivity factor Q=1 and radiates 3 dB more towards the garden than a free-standing unit. In a corner between facade and fence that grows to 6 dB. Tucking the unit away in a corner often backfires acoustically.

Does a fence or garden wall help?

Yes — provided it is heavy and fully closed. The tool (and the official WPAC method) only counts boundary screens that are completely closed and weigh at least 10 kg/m². A standard wooden fence with gaps does not qualify; a masonry wall, concrete fence or purpose-built noise screen does. The sound is then assessed half a metre above the screen, with a 5 dB correction.

Important: a screen mainly protects the zone directly behind it at ear height (the assessment height is 1.5 metres). Upper-floor windows of the neighbours look straight over it — check those with an extra receiver position at window height (“+ Receiver position” button).

How does the calculation work?

The calculator is based on WPAC-geluid V2020, the official Dutch calculation tool for noise from outdoor heat pump and air-conditioning units, developed for the Ministry of the Interior. It computes the sound transmission loss (D) from the outdoor unit to each assessment point: the larger the transmission loss, the more sound power the unit is allowed to produce.

Distance is the dominant factor: every doubling of distance reduces the level by 6 dB. The directivity factor Q also matters — a unit within 2.5 metres of one wall (Q=1) is 3 dB louder than a free-standing unit (Q=2), and a corner between two walls (Q=0.5) adds another 3 dB. Reflections from building walls raise the level, while buildings between the unit and the assessment point screen the sound.

The transmission loss yields the maximum allowable sound power (LwA) of the unit: max LwA = limit + D − margin. The safety margin (default 3 dB, minimum 2 dB) covers design and measurement uncertainty. Compare the calculated maximum with the sound power on the unit’s energy label or product documentation.

The noise limits in brief

Since 1 January 2024 the noise requirements for heat pumps and air conditioners are set by the Besluit bouwwerken leefomgeving (Bbl), the successor to the Dutch Building Decree 2012. Article 4.107(2) Bbl states that an outdoor heat or cold generation installation may cause at most 40 dB at the boundary with a neighbouring residential plot. For situations on the same plot — such as apartment buildings — the same limit applies at openable windows and doors of another dwelling (article 4.108(3) Bbl).

The 40 dB limit applies in the evening and at night (19:00–07:00). If the unit has a low-noise setting (silent mode) active during that period, a limit of 45 dB applies during the day (07:00–19:00). Without silent mode the unit must meet 40 dB during the day as well. Read more on the heat pump noise limits page.

Frequently asked questions about this situation

How far must a heat pump be from the property boundary?

There is no legal minimum distance. The requirement is a maximum of 40 dB at the boundary (evening and night). How many metres that takes depends on the unit’s sound power, directivity and screening — exactly what this tool calculates. Rule of thumb: a typical unit of 55–60 dB(A) sound power easily needs 3 to 5 metres of free distance without screening.

Does an ordinary wooden fence help against heat pump noise?

An open or lightweight fence (gaps, under 10 kg/m²) does not count as a noise screen in the formal assessment. In practice it attenuates a few dB at most. If you want the screen to count, choose a closed masonry, concrete or acoustic-screen construction of at least 10 kg/m².

May the heat pump stand against my own facade?

Yes, but within 2.5 metres of the facade the directivity factor worsens (Q=1 instead of Q=2), making the unit 3 dB louder towards the neighbours. The tool applies this automatically based on the position you choose.

Does the limit also apply at the front, towards the street?

The limit only applies at boundaries with a residential plot. If the front borders a public road, no requirement applies there — untick that side under “Residential zoning”. Note that the rule can apply again across the street if the distance is small.

Calculate other situations

On extension On outbuilding On the roof Apartment

Further reading

This calculator provides an indicative result based on WPAC-geluid V2020 and does not replace a formal acoustic study. When in doubt, consult an acoustic consultant or your municipality.