Whether you are installing a heat pump and want to stay neatly within the Dutch 40 dB limit, or want to quieten an existing installation: outdoor-unit noise can be reduced considerably with the right measures. The tips below are roughly ordered by value for money — the first three cost little or nothing. You can calculate the effect of most measures in advance with the free calculator.
- 1
Increase the distance to the boundary
The cheapest measure is free: distance. Every doubling of the distance between unit and assessment point gains 6 dB. Going from 1.5 to 3 metres gains as much as going from 3 to 6 metres. Move the unit around in the calculator and see the effect instantly.
- 2
Avoid corners and recesses
A unit in a corner between two walls beams its sound into the garden: up to 6 dB worse than a free-standing position (directivity factor Q). One wall within 2.5 metres already costs 3 dB. The "convenient" spot in the corner behind the shed is acoustically often the worst choice.
- 3
Use silent mode — and schedule it
Almost all modern heat pumps have a low-noise setting. Schedule it from 19:00 to 07:00: the more generous daytime limit of 45 dB then applies instead of 40 dB. The heat pump easily makes up the missed capacity during the day.
- 4
Fit vibration dampers
Much "noise nuisance" is not airborne sound but structure-borne: vibrations travelling through the foundation, wall bracket or roof structure into your house or the neighbours'. Rubber dampers or a decoupled mounting frame are cheap and belong in every professional installation.
- 5
Consider an acoustic enclosure
A good enclosure (off-the-shelf or custom) attenuates 5 to 10 dB, provided the airflow is not choked — otherwise the fan works harder and louder. Enter the attenuation as "D omkasting" in the equipment specs of the calculator to see the effect on the assessment.
- 6
Place a noise screen or garden wall
A fully closed screen of at least 10 kg/m² (masonry, concrete, solid timber without gaps, or a purpose-built noise screen) between the unit and the boundary yields about 5 dB of headroom in the assessment. Note: a screen mainly protects low points — neighbours' upper windows look over it. Test the effect with the screen option in the calculator.
- 7
Choose a quiet unit (check the LwA on the label)
Units differ enormously: sound power (LwA) ranges from about 48 to over 65 dB(A). The LwA is mandatory on the energy label and product fiche. Add the tonal penalty K1 if the unit produces audible pure tones — ask the supplier. Every dB quieter at the source is a dB less of a problem at the neighbours.
- 8
Keep the unit in good condition
A fouled or worn fan, loose panels and rattling brackets make a unit louder over the years — and irregular noise stands out. Periodic maintenance keeps the level at specification. Icing (a poorly working defrost cycle) is another well-known source of extra noise.
- 9
Talk to the neighbours before installing
Most neighbour conflicts about heat pumps arise not from the decibels but from the surprise. Tell the neighbours what you are planning, share the noise calculation (via the share button in the tool) and pick a spot that works for them too where possible. It is also strong evidence of due care if a dispute arises later.
Which measure first?
Start at the source and the positioning: a quieter unit in a smart spot solves more than any add-on measure. If that falls just short, silent mode and a screen or enclosure are the logical next steps. Calculate every variant before investing — a screen that does not break the sight line to the critical point achieves next to nothing.
Further reading
- Calculate your situation with the free tool
- How far must a heat pump be from the boundary?
- The Dutch noise limits for heat pumps explained
- Noise nuisance from the neighbours' heat pump?
- Frequently asked questions
The dB values mentioned are indicative and depend on the specific situation. Have major investments (enclosure, screen) calculated in advance by an installer or acoustic consultant.